T962 Reflow Oven? - Page 1
Forum section: electronics / general

author: jpanhalt
author_rank: Super Contributor
timestamp: March 18, 2020, 10:41:02 pm
content: Any comments about or experience with the imported T962 reflow oven? Is the only problem the controller?Comments on 63/37 solder paste that is not Kester brand? My only experience over many years is with Kester rosin core solder.Thanks, John

author: Dubbie
author_rank: Unknown
timestamp: March 18, 2020, 10:56:57 pm
content: I have one.I replaced the firmware and did the other mods floating around the net.pretty happy with it. All my boards seem to come out very well.I initially intended to use the shipping firmware, but it really is completely unusably terrible.

author: coppice
author_rank: Super Contributor
timestamp: March 18, 2020, 11:31:10 pm
content: People tend to find that the Qinsi QS-5100 is like a T962 with most of the really bad issues fixed.

author: Bud
author_rank: Super Contributor
timestamp: March 19, 2020, 01:01:32 am
content: Quote from: jpanhalt on March 18, 2020, 10:41:02 pmI use MG Chemical 4860P 63/37 no clean one and am happy with it.Edit: i prefer Kester but it is hard to find here

author: jpanhalt
author_rank: Super Contributor
timestamp: March 19, 2020, 04:01:17 am
content: Thanks for the comments. I have been watching T962 prices for awhile. I picked up a new one ( I hope) for less the $200 including shipping and tax and plan to implement most of the improvements to the firmware and other issues that are described on the internet. They are summarized on GitHub.MG solder was going to be my first option as the company has been around awhile.

author: asmi
author_rank: Super Contributor
timestamp: March 19, 2020, 05:12:57 pm
content: I used it too for last 3 years, after some HW modifications and firmware change. The only problem I ever had was with connectors made by Molex, all others worked just fine. Only recently I grew out of it, so I ordered ZB2520HL oven, which I will hopefully receive in the next week or two.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 19, 2020, 07:56:33 pm
content: @asmiWhat was the problem with Molex? Were the footprints off, did the plastic melt, or something else. Molex uses a variety of different plastics. If you can recall one that failed and any other that didn't, I'd like to look into it.

author: asmi
author_rank: Super Contributor
timestamp: March 19, 2020, 08:28:46 pm
content: Quote from: jpanhalt on March 19, 2020, 07:56:33 pmThe footprints were/are OK. The plastic they use seems to be especially susceptible to IR reflow, so it meltedAs you can see, other connectors are just fine. So now I try to avoid using Molex parts if I can, and if I must, I solder them manually after reflow. It really is puzzling when even cheap-ass Chinese parts from Aliexpress survive IR reflow with no problems, but a well-known brand ones can notIf you want to know specific part numbers of these parts pls let me know - I can try to dig them out as I should still have some leftovers.Now I prefer using Samtec connectors, their plastic is not affected by IR at all, and they have the best online services - they don't force you to fill out a form with millions of fields if you want to get some samples for fit-checks, you can order in-stock parts directly with no MOQ nonsense, they have 3D step models for most of their parts publicly accessible. But unfortunately they don't make some types of connectors I use, so I have to use others every so often.

author: coppice
author_rank: Super Contributor
timestamp: March 19, 2020, 08:36:32 pm
content: Quote from: asmi on March 19, 2020, 08:28:46 pmThis makes no sense at all. They melted because of the type of plastic, not the company that moulded it. Molex use many types of plastic across their range of connectors, as does every other maker. Some plastics offer higher strength, or a greater temperature range, or greater flexibility, or very low cost, and its up to you to choose something that suits your needs.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 19, 2020, 08:55:41 pm
content: @asmiI agree it is the type of plastic, which seems obvious, but a generic descriptor like "polyamide" (Molex) may not be the same a "polyamide PA6T" (JST) just as epoxy FR4 can have many different temperature ratings. Unfortunately, my current design uses both a Molex Pico-Lock and Pico-EZmate for space reasons. I am sure there is a JST equivalent for one but not the other.If you have the time to find the part number for one of the Molex connectors that melted, I will dig into it. I have a background in organic chemistry.I might add that I modified the footprints for both by elongating the pads to allow hand soldering, but still, it would be nice to know what to watch for.EDIT: As suspected polyamide 6T may be quite different from a generic version:Quote

author: KE5FX
author_rank: Super Contributor
timestamp: March 19, 2020, 09:52:43 pm
content: Similar experience here. Results from my T962 with ESTechnical mods generally range from acceptable to excellent, but the plastic used in certain parts often shows some heat damage. JST connectors such as SM04B-SRSS-TB(LF)(SN) seem hopeless, as do Mini-Circuits parts with the CD636 plastic package such as ADP-2-10+.It probably has more to do with the plastic's IR absorption characteristics than anything else. There is only so much you can expect from an oven that blasts the board with IR at extremely close range, even with added airflow. These parts all look fine on boards that have been factory-assembled on an industrial-quality SMT line.

author: asmi
author_rank: Super Contributor
timestamp: March 19, 2020, 09:53:09 pm
content: Quote from: coppice on March 19, 2020, 08:36:32 pmI'm telling you what worked for me, and that is avoiding their parts. If you have a different experience - feel free to share with us. I don't have anything againts Molex as a company - it's just their parts tend to cause problems for me - hence my tendency to avoid them.

author: asmi
author_rank: Super Contributor
timestamp: March 19, 2020, 10:01:16 pm
content: Quote from: jpanhalt on March 19, 2020, 08:55:41 pmFirst photo - parts 54104-4031 and 52271-0679. Parts deformed enough to become non-functional.Second photo - 87832-1420. Part deformed significantly, but I was able to restore functionality by cutting away melted parts of shroud.I suggest you to do a "dry run" before reflow and see if parts you plan to use will survive. Also once you receive your oven and you do all HW modifications (cold junction mod is the most important one, along with community FW), take your time to calibrate the oven. Also never place board to be reflowed straight on a drawer - it will suck a lot of heat off the board and reflow might fail because of that. I use makeshift standoffs made from M3 screws and a couple of nuts, or just a few old scrap PCBs if the board doesn't have mounting holes. This was required for most of my boards anyway due to double-sided components placement.For solder paste, I use and highly recommendthisone as it's room temperature stable, so no need for refrigeration, plus it doesn't dry out after you print it onto a board, giving you plenty of time to place all parts (this one is super important for me as often have 200+ parts per side).

author: asmi
author_rank: Super Contributor
timestamp: March 19, 2020, 10:04:37 pm
content: Quote from: KE5FX on March 19, 2020, 09:52:43 pmI just recently reflowed a board with ADTT 1-6+ and it came out OK - plastic became a bit darker, but it's hardly noticeable (unless you put a clean part right next to it), and most importantly it didn't seem to affect functionality.

author: Mangozac
author_rank: Frequent Contributor
timestamp: March 19, 2020, 10:09:12 pm
content: We too have issues with the plastic on Molex FFC connectors and certain pin headers in our modded T962. It depends on proximity to the elements so I just assumed poor heat distribution. The irony is that we don't have any issues with cheaper alternative connectors!Overall the T962 does the job though and is good value at the price point.

author: asmi
author_rank: Super Contributor
timestamp: March 19, 2020, 10:36:51 pm
content: I remember someone reported good results by placing small foil "caps" on top of these connectors to protect them from direct IR radiation. I suspect kapton tape would also work.

author: coppice
author_rank: Super Contributor
timestamp: March 19, 2020, 10:39:03 pm
content: Quote from: asmi on March 19, 2020, 10:36:51 pmA lot of connectors come with a kapton film that must be peeled off after assembly. It both avoids stuff getting on the contact pins, and protects the plastic.

author: KE5FX
author_rank: Super Contributor
timestamp: March 19, 2020, 11:35:57 pm
content: Quote from: asmi on March 19, 2020, 10:04:37 pmYeah, the MCL parts get a bit scorched (which I don't like, but can usually live with) but the name-brand JST connectors melt like they're made of butter. There's no excuse for building those out of low-temperature plastics.

author: Mangozac
author_rank: Frequent Contributor
timestamp: March 20, 2020, 01:15:47 am
content: Quote from: coppice on March 19, 2020, 10:39:03 pmThat's a good idea and definitely worth trying!

author: jpanhalt
author_rank: Super Contributor
timestamp: March 20, 2020, 11:46:44 am
content: @asmiI checked into the three Molex part numbers and found nothing striking.#54104 4031 is polyamide (PA46) or Nylon 4/6 which is one of the higher temperature Nylons/polyamides (Nylon is a polyamide)(melting point 295°C). The actuator is polyphenylene sulfide (PPS)#52271 0679 is also polyamide (PA46) and PPS for the actuator.#87832 1420 is described simply as polyamide.The first and last connectors are black; the 4031 is tan. Color may have something to do with sensitivity in IR heated ovens versus hot air. Also, construction details such as PCB attachment legs size and relationship to the bodies may be a factor. Another common "plastic" used is described as "liquid crystal polymer." They are also said to be more heat resistant than earlier/cheaper plastics (https://www.steinwall.com/wp-content/uploads/2016/05/Liquid-Crystal-Polymers-LCP.pdf).As suggested by others, a reflective shield (e.g., Kapton or aluminum foil) over sensitive components may help. I use little pieces of aluminum foil to protect parts when using hot air. It doesn't stick like tape, but is so easily formed that it stays put. I will definitely try that.My T-962 should be here in a day or two. I appreciate the input from all of you and have a little more confidence in using the modified T-962 instead of a toaster oven.Regards, John

author: asmi
author_rank: Super Contributor
timestamp: March 20, 2020, 08:33:47 pm
content: Quote from: jpanhalt on March 20, 2020, 11:46:44 amYea, that's why I prefer just trying it out and seeing what happens. It's always better to sacrifice one part to find out that it can't withstand IR reflow, then to find this out during actual reflow of assembled board and then trying to remove it from completed board. Some of my boards have quite a lot of parts on them, so removing (usually) large parts can be quite a headache.Quote from: jpanhalt on March 20, 2020, 11:46:44 amTake your time to calibrate the thermocouples once you install community FW (it allows setting gain/offset for each probe independently). Also like I said above, consider using room temperature stable solder paste - it's a bit more expensive, but to me it's totally worth it because it doesn't need to be stored in the fridge, and it doesn't dry out once printed. Also use first few boards to tune reflow profile such that you will have boards fully reflow, but don't burn anything up. The oven tends to lag a bit behind the program, so include a soak phase if you reflow multilayer boards with power/ground planes - these can take in quite a bit of heat.Oh and remember to have some sort of arrangement to remove smoke/fumes that come out from the back of the oven during reflow (typically they come off once the reflow goes from peak temperature into chill-down and fan on the back turns on).

author: jpanhalt
author_rank: Super Contributor
timestamp: March 20, 2020, 10:55:11 pm
content: Thanks for all the good advice. I can see it's going to be a journey. Tried to download "Flashmagic" to load the hex file, and Google blocked it as "dangerous," malware, or pup.Need to look into that more as my only experience has been with PIC's, and for a one-time effort, it is hard to justify buying anything.

author: KE5FX
author_rank: Super Contributor
timestamp: March 21, 2020, 01:07:31 am
content: Quote from: jpanhalt on March 20, 2020, 10:55:11 pmThat's interesting. Flash Magic is a pretty common utility application. What site did you try to download it from?

author: jpanhalt
author_rank: Super Contributor
timestamp: March 21, 2020, 03:30:33 am
content: Quote from: KE5FX on March 21, 2020, 01:07:31 amFirst downloaded from FlashMagicTool.com (http://flashmagictool.com) in early afternoon. Just tried again (11:25 PM EDT). File is FlashMagic.exe, 37.9MB . Downloads, but if one tries to open it, there is a delay of a few minutes, then message,"FlashMagic.exe man be dangerous so Chrome has blocked it." appears. If one clicks on more info you just get a general message as stated below.Edit: The link to Flashmagictool.com was on electrosome.com (https://electrosome.com/flashing-lpc2148-serial-isp-bootloader/)

author: arvidj
author_rank: Contributor
timestamp: March 23, 2020, 02:49:23 am
content: What appears to be the best firmware to flash?

author: jpanhalt
author_rank: Super Contributor
timestamp: March 23, 2020, 05:01:20 am
content: Mine arrived on Saturday and I dug into it today. Its MCU is an LPC2134. Some of the procedures are for the LPC2148 (newer). At first glance, the boards may be slightly different. I need to find out whether the difference in the image of the LPC2148 board is a modification done by the user or from the factory.Also need to be sure the hex file for the LPC2148 is compatible with the LPC2134 or visa versa.BTW, the FlashMagic problem was a Google Chrome security setting (as suspected). That was easy to work around.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 11, 2020, 06:10:54 pm
content: My questions are really noob. I always write my own code (with help) and have never downloaded a library much less a hex file. I also write in Assembly, use an Assembler, and have never used a C compiler.1) The hex file linked in post #10 here (https://www.eevblog.com/forum/reviews/t-962-reflow-oven-anyone-done-the-github-firmware-mod/), and on other sites all decompress to more than 125 kB. At least that is what the file size on my Win7 PC says. The LPC2134 chip used has 125 kB of flash memory. Is that an issue? Are the byte sizes the same?2) Does that hex file (0.5.2) support the Dallas DS18B20 1-wire sensor, or does one have to add an additional file?

author: donotdespisethesnake
author_rank: Super Contributor
timestamp: April 12, 2020, 01:06:13 pm
content: Hex files are ASCII, so the size won't match the binary size.0.5.2 supports DS18B20.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 12, 2020, 01:47:47 pm
content: Thanks, I suspected something like that -- particularly after I checked the default hex file that is also on GitHub. It was confirmed this morning when I finally had the guts to load 0.5.2 file into FlashMagic.My problem now is getting into bootload. I keep getting the dreaded message about autobaud not configured. Also, no crystal frequency is shown in the starting page. I am thinking about re-installing FlashMagic.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 12, 2020, 09:37:10 pm
content: Have spent more than a day trying to get FlashMagic v.2.12.28.0 (current) to recognize the chip.Chip (LPC 2134/01) seems to enter bootload mode (screen blank, both LED's lit) using the standard procedure of holding n_RESET low, touching n_ISP low, then floating both, but all attempts to communicate (changing bauds, swap TX and RX, change settings, follow trouble shooting "tutorials" on the internet -- about 14 hours of frustration) fail and all I get is the dreaded and very common,"Operation Failed. Failed to autobaud - Step 1" error.My FTDI connector (232R-3V3) is about 6 or 7 years old, so I loaded X-CTU (Digi corp) and tested echo. That worked.Connection is to "com 6." I have tried every baud available from 9600 to 115200.Any ideas? Could an older version of FlashMagic offer any hope? If so, what version have you had success with? My PC is running Win7 32/64.

author: SMdude
author_rank: Frequent Contributor
timestamp: April 12, 2020, 09:49:15 pm
content: I remember when I did my oven I had the same problem and it did my head in, however I can't for the life of me remember what I did to solve it!I kind of think it might have been a logic voltage level problem. Uart, 5v, 3.3v?

author: TomS_
author_rank: Frequent Contributor
timestamp: April 12, 2020, 11:27:07 pm
content: One common problem I see that continually pops up with these ovens is connectors that burn or melt.It may not necessarily be a problem with the machine, and maybe just needs some experimentation with different manufacturers or flavours of connectors to find the ones that play well. Or Ive also seen suggestions that the connectors need to be capped or covered to prevent direct IR exposure.Ive been looking at one for a long time as well, so interested to hear what other people experience in this respect.

author: KE5FX
author_rank: Super Contributor
timestamp: April 12, 2020, 11:44:49 pm
content: Quote from: jpanhalt on April 12, 2020, 09:37:10 pmFlash Magic is kind of a dumpster fire IMO.I have a command-line programmerbased on an open-source release by Martin Maurer that works well with at least some devices in the family (specifically, I've used it with the LPC1837 and LPC18S37.) Curious to hear if it works on the LPC2134, if you want to give it a try. The usual caveats apply -- it may brick your MPU, burn down your house, or cause cancer in California.Quote from: TomS_ on April 12, 2020, 11:27:07 pmYeah, absolutely, it takes a while to dial it in. Be sure to order several spares of any plastic connectors you plan to use. An IR oven this small can be very handy but it will never work perfectly in all cases. Nature of the beast.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 13, 2020, 12:15:52 am
content: Thanks,I am in Ohio, so any cancer it causes in California won't affect me.On the second matter of melting stuff, since this is my first shot at reflow, I chose components that I could also hand solder. One troublesome part was a 12-pin 0.5 mm ZIF for FFC/FPC. I tried a few connectors that looked about right and settled on the Molex type 1084 (Digikey WM11084-CT-ND, Molex #0528921233). The pins were about the same on all 4 of the choices I tested, but that device had exposed mounting lugs. Tried it and with care, it can be hand soldered without damage to the plastic..

author: jpanhalt
author_rank: Super Contributor
timestamp: April 13, 2020, 05:55:08 pm
content: Here's another follow-up.After many more hours, I hooked up an oscilloscope to the FTDI and ISP pinheaders. Signals are getting to Pin 4 of the ISP, which is RXD. Response (Pin 3) is completely dead. Even though the screen is blank or messed up, both leds on the front are on, and the red LED on the board is off, nothing.I have tried getting into bootloader mode starting with power up (i.e., Pin 1 is grounded at power up and after the MCU boots into normal operating mode. Same result.Cables to the heaters and TC's are disconnected to give more working room, but I don't see how that should affect getting into bootloader mode.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 15, 2020, 06:14:54 pm
content: I am beginning to think the TX function of the LPC2134 on my board is dead. It boots fine, but takes awhile. All attempts to get it to acknowledge a ? have failed.The TX pin (#19, P0.0) stays low. Resistance to ground is about 140 Ω. Tried pulling it high with a 4.7 k resistor to no avail.Does anyone know what the resistance from that pin to ground should be? On my FTDI cable the corresponding pins are pulled high.

author: Weston
author_rank: Regular Contributor
timestamp: April 16, 2020, 02:02:43 am
content: The TX pin is an output so I would expect it to read low resistance. Serial idle state is V+ though. Can you check the voltage on the pin? It should be ~3V3.I would assume that the chip goes through a full reset on power up, but you should try cycling the reset pin too as detailed here:https://github.com/UnifiedEngineering/T-962-improvements/wiki/Flashing-the-LPC21xx-controllerI used the flash utility for linux, not flash magic, but I just upgraded the firmware on my oven last week following the instructions on the git repo and it went fine.As a side note, has anyone noticed a temperature gradient across their T962? The whole oven looks rather symmetrical from left/right, but the right side of my oven is consistently ~ 25C hotter than the left, as measured with an external thermocouple. It's not that big a difference, I should be able to reflow PCBs on the left without nuking PCBs on the right, but it's still a bit concerning.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 16, 2020, 09:50:34 am
content: Quote from: Weston on April 16, 2020, 02:02:43 amThe pin stays low (~0.0 V) when measured with an oscilloscope and DMM.It was only after days of trying everything on GitHub and elsewhere that I tested resistance to ground. Pulled the header off the board to look for shorts that might be hidden. None. Even touching a lead from the 4.7 k resistor added for the cold junction modification did nothing.

author: Weston
author_rank: Regular Contributor
timestamp: April 16, 2020, 10:12:25 am
content: It seems possible you could have blown the chip then, but I don't see how you could have easily. Even if you connected tx to tx it would have likely survived. Is your computer a desktop and you plugged in the serial cable RX pin in first or something? I have killed boards with setups like that before due to floating potentials being discharged though grounded equipment.However, even before checking the TX pin, it seemed you were having issues with the flash utility. It might be worth trying to set up something running linux to run the makefile based flash procedure provided in that repo. I had no issues in Ubuntu 18.04 using ~ the cheapest USB <> serial cable sold on amazon (https://www.amazon.com/JBtek-WINDOWS-Supported-Raspberry-Programming/dp/B00QT7LQ88/).Worst case, if you have fried the microcontroller you should be able to get a replacement off digikey.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 16, 2020, 11:49:45 am
content: It is a desk top computer. The cable is FTDI TTL-232R-3V3. I have used both a terminal emulator (Digi) that I have used to setup XBee and Flash Magic.At first, I just set TX --> RX and RX --> TX as usual. After getting no results, and since some of the many "tutorials" said it should be TX --> TX, which didn't make sense, I tried that anyway. No luck. Then I started trouble shooting, set up a scope, etc., and everything has been TX --> RX as usual. The FTDI cable with either program works exactly as expected. With the terminal emulator, it echos just fine too.When I noticed TX from the LPC2134 was always low, I removed the board, and visually inspected for soldering shorts. Saw some shadows I didn't like. Upon cleaning, those turned out to be old flux, not solder. Re-install. Same problem. At some point, I used my DMM to check continuity. Continuity was OK, but resistance to ground was low on the TX pin. A weak pull-up didn't work.My working hypothesis is that something like latch-up has affected that pin. A new chip was ordered from DigiKey yesterday and is expected Saturday.Reviewed the NXP User Manual and will try some things to the RX in hopes of unlocking the TX. The datasheet does mention the possibility of I/O pin latch-up at 100 mA. I certainly didn't apply anywhere near that current intentionally when using a 4.7 k pull-up. The maximum output current for the FTDI cable is listed as 75 mA, so if I fried it, it was my fault when I swapped the lines.BTW, I did notice one small difference from the schematic on GitHub. That shows the ISP pin (P0.14) pulled up to +5.0 V; my board has the pull-up resistor to the 3V3 rail.As for using Linux, I am just not savvy enough to start that journey now. Will just stick with the Digi emulator to send commands. If I can get the chip's TX to respond, I will be happy. Otherwise, I have a few hours work to do on Saturday.

author: Dubbie
author_rank: Unknown
timestamp: April 16, 2020, 09:50:28 pm
content: Sorry to hear that you have had such a bad experience.I hope that replacing the uC will sort things out for you.Flashing the new firmware was extremely painless for me, so I am thinking there must be something deeper wrong with your hardware. You seem to have exhausted all of the basic troubleshooting steps.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 17, 2020, 04:11:01 pm
content: UPDATEThe LPC2134 chip arrived a day early and is installed. It's alive. On the removed chip, TX (P0.0, pin19) read the same 145 Ω to ground as it did in circuit. The new chip shows the TX at the expected 3.3V. In terminal, it echos a '?' , but Flash Magic is giving an error when I ask to start bootloader: "Start Root ROM command _ no '.' received."If I do "Start" instead without a hex file loaded, the error is as expected, "No hex file loaded."At least there is light.Presumably, boot loader is started with POR when ISP is grounded, and then released. Is there a need to go through the "start bootloader" in Flash Magic?

author: jpanhalt
author_rank: Super Contributor
timestamp: April 17, 2020, 07:45:51 pm
content: UPDATE#2Kept having problems with communications when I started with "start bootloader." So, I figured a new chip must be empty and the chip most likely enters bootloader on POR since there is no valid user program (see flow charts in datasheet).I booted with ISP grounded (P0.14) (probably not needed). Reset pin was left open. Set baud to 57,600 and hit program. I had my scope on the TX and RX lines as I wanted to see the handshaking and really didn't expect it to work. If I were to do that again, I would disconnect the scope to reduce chance of noise.Programming took off. Every unit was programmed, except verify sent an error: "difference in value stored at 0x0000 0000" It did not say what the expected and found values were. The progress showed every page (?) programmed, including 0x0000 0000 - 0000 03FF.Shut everything down, turned it on, and the Unified Engineering splash screen came up. After connecting the TC's, oven temp showed 26°, which was about right within a couple of degrees.Tomorrow, I will attach the Dallas temp sensor and give the thing a try.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 18, 2020, 08:37:17 pm
content: UPDATE #3 QuestionsGot it all back together. The 1-wire sensor I have is made by Maxim, so presumably works in parasitic mode, which is how I set it up.1) How can one monitor the cold junction temperature during a run? Switching to manual mode shows a cold junction temperature, but I have reason to doubt its accuracy. Did you do the 1-wire version or run a 3v3 line to the Dallas/Maxim sensor?2) There are instructions for the modifications everywhere. Is there a consolidated user's manual for the modified oven?

author: Dubbie
author_rank: Unknown
timestamp: April 20, 2020, 09:21:37 pm
content: I did the one wire temp sensor. I do remember that the first sensor I bought, I could not get to work. I mistakenly bought a Maxim DS18S20+-ND the first time. I then bought a DS18B20+-ND and that part worked fine.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 20, 2020, 09:39:48 pm
content: My sensor seems to work in parasitic mode. It's the Maxim version. Occasionally, it gives a bizarre cold-junction temp, such as 85°C. Turning the oven off and on again fixes that. A bit unsettling, but the firmware is free.I have a Fluke TC and calibrated mercury thermometers. The Fluke agrees within 0.5°C of the mercury thermometers up to 200°C (highest temp tested). The oven thermocouples are all over the place individually, but surprisingly, by tweaking the offset and gains, the "actual temperature" matches that thermocouple within a few degrees when it is placed in the oven center and at the same height as the PCB's will be.Will run some reflow tests tomorrow with Kester EP256, which is fresh and within expiration date.

author: Weston
author_rank: Regular Contributor
timestamp: April 20, 2020, 11:26:21 pm
content: Congrats on getting it working!I also had the cold junction temp jump to 85C a few times in bake mode. I believe that 85C is the temperature it initializes at so something is funky with the sensor or the library to talk to it. This thread shows there are lot of fake ds18b20:https://www.eevblog.com/forum/projects/fake-ds18b20/. I got my sensors from a friend who ordered them off amazon, so I assume they are fake and that is what causing the issue, I will have to add some real ones to my next digikey order. On the plus side, it seems they will read either 85C or something close to the real temp, so its not going to cause your boards to bake or the oven to catch fire.I was able to get the individual thermocouples to match an external meter pretty well, but there is still a ~15C difference between the left and right side of the oven. I assume its an issue with non-uniform insulation or heater bulbs.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 21, 2020, 12:02:39 am
content: Quote from: Weston on April 20, 2020, 11:26:21 pmMy DS18B20 is direct from DigiKey. Maxim is the manufacturer.Quote10° to 15°C is about what I am seeing. The TC's are quite fine wire that is twisted together for a short distance (3/16" or so) and with what looks like a small weld at the tip. I did something similar with slightly heavier wire and used my CD welder to weld the tip. It raised havoc with the MAX31856 TC digital amplifier I am using in a real project ( got the T-962 to reflow that board). It made the RDY interrupt interrupt unreliable, particularly if you moved it slightly. We used to make them in school using a hydrogen/oxy torch. I don't have that anymore, but I used my TIG welder to make these:Those were just for practice. I avoid the twist and have only one junction. They work much better with the MAX31856, and I have had no problems with the interrupt since. I am considering removing the TC's from the oven and re-welding them. Being bigger, the ones shown have a little more lag, so I will probably use the original TC wires that came with the oven.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 21, 2020, 01:29:17 pm
content: TEST RUN OKI got the internal TC's to agree reasonably well compared to my Fluke TC, which agrees well with a mercury thermometer. Set L gain = 1.0, offset = -5.0 and R gain = 0.82, offset =.25. One cause for big differences between the two TC's seemed to be slow fan speed, so I set the min to 20 and may consider going higher.Did a trial board with Kester EP256, which has a recommended peak temp of 208° to 230°C. The actual lagged bethinfd the set, but did reach that range and reflow looked decent (just used dabs of paste and no stencil for this test).Unfortunately, I didn't plan ahead to photograph the curve, so I had to hand hold the camera. Sorry for the blur:John

author: Dubbie
author_rank: Unknown
timestamp: May 10, 2020, 09:38:13 am
content: Nice one. I look forward to seeing a full populated board flowed!

author: ttt
author_rank: Regular Contributor
timestamp: July 11, 2020, 08:56:55 pm
content: So I just finished upgrading my T962A+ with a couple of circulation fans. This was not obvious as the fan motor needs to be outside the chamber of course.Ingredients:- A couple of cheap RC DC hobby motors- Shaft holder is a 50mm M6 all thread with 3.5mm bore.- Drive shaft is a 2mm Stainless Steel Rod with threads at the end- flat steel sheet as fan blades (Don't use aluminum, it'll droop).- Extra hardware to hold it all togetherConclusion after reflowing a few boards: Night and day. Lead free solder melts evenly and consistently on my 300x150mm boards. And that's with the default controller board.This was inspired by Jerry Walkers mod:https://youtu.be/9026Odx_jOw?t=752

author: jpanhalt
author_rank: Super Contributor
timestamp: July 11, 2020, 09:06:13 pm
content: Nice job. I still have very limited experience. Once Springs comes, I am busy on a small farm. Improving circulation, not exhaust, seems an obvious way to improve.

author: peter-h
author_rank: Super Contributor
timestamp: June 22, 2021, 11:17:33 am
content: This is just an update in case anybody is looking to buy this oven.I bought one one Ebay. At £150 one can't argue even if it is crapand indeed it is pretty well crap!Good points:Mechanically sturdy, the drawer works. Chinese do sturdy metalworkVery cheap!Bad points:Airflow is crap. The design is truly dumb. To achieve circulation, they use an external fan to blow outside air into the oven! No domestic oven does that; they all have an internal impeller and they recirculate the internal air. If you set the fan speed anything above the absolute min at which is just about runs, the oven never reaches any soldering temperature, and there are huge differences between the two thermocouples - up to 80C.Generally shoddy build. Masking tape all over the place inside - smells when hot and has to be replaced with kaptop tape - this issue is documented all over the internet but the mfg obviously doesn't read itI installed the ES Technical controller replacement which was another £150https://www.estechnical.co.uk/products/reflow-oven-controllersThis is a good product. However I have to say the installation is not trivial. One has to cut in half the existing controller PCB, so just the mains switching portion is left. The procedure involves unsoldering a terminal block, which would be difficult but luckily I have a bandsaw and when I cut the board across I just sawed right through the terminal block and the unwanted part just fell offThey should have just done everything on one PCB. But it works great. Of the two thermocouples they use just the 1st one, and it seems to be the 2nd one which shows the duff (way too high) temperature.Using a precision PT100 thermometer and by pulling out the two TCs I proved that both read accurately, within 1-2C, with the right temps displayed on the LCD. So it is just an airflow issue.Luckily my oven was an older model which doesnothave the extraction duct on the fan, so I didn't need to do a more difficult mod which involves removing some "automatic" slats.I think the oven needs a mod with an internal impeller, driven from a little DC motor. I might install that later, probably via the bottom which is accessible (the oven will need taller feet fitted). But it may not be needed if I find that actual measurements on a PCB are ok.The ES board has a serial output on which it streams various parameters in CSV format, continuously. Not tried this yet.I will report in due course on how this oven works for soldering.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 22, 2021, 12:05:33 pm
content: Quote from: peter-h on June 22, 2021, 11:17:33 amI can only agree in part. Yes, the air flow might be improved; however, I found with my independent TC's (as described earlier) that temperature control across the oven is better with higher fan speeds. Each TC can be adjusted to read relatively close to the external TC's. Attached is the Kester recommended profile for 63/37 solder. Second attachment is actual profile shown on the T962 screen. Actual peak was 235°C. Leaded solder does reflow.Sorry for the blurred image. Handheld and close ups do not work well for me.EDIT: Original control board with United Engineering firmware.

author: peter-h
author_rank: Super Contributor
timestamp: June 22, 2021, 01:09:54 pm
content: I found that with higher fan speeds the oven never reaches the required 220C or so (fairly obviously due to the amount of cold air arriving) and the controller gives up with an error message.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 22, 2021, 02:00:51 pm
content: With different firmware and hardware, my conditions may not apply to you.Here are some data from my testing and comparing temperatures in °C on the T962 screen with TC readings (Fluke):Screen "actual" : 202°Fluke TC : 199°Oven TC (L): 200°Oven TC (R): 202°Fan speed: 30Cold Junction: 21.5°TC settings:L(gain): 1.0L(offset): -5.00R(gain): 0.82R(offset): +0.25I have vacillated between a minimal fan speed of 30 and 20. My current setting is 20. Hope this helps. BTW, it's "Unified Engineering," not United.Edit: changed fan speed to minimal fan speed

author: peter-h
author_rank: Super Contributor
timestamp: June 22, 2021, 02:39:46 pm
content: Maybe your "fan30" is my "fan10". These controllers are still applying full mains voltage to the fan, but on a low duty cycle. This is the only way; the fans are not capable of being speed controlled like some DC motor, or a 3 phase brushless AC motor.I also see that you have done what looks like thermocouple calibration. You have 1.0 on one and 0.82 on the other. That is adramaticcorrection. It corresponds to about 40C at 200C. Thermocouples should not need that. They should be accurate to within a few degrees C and usually better. I do this in my day job.The controller I am using doesn't have any calibration options and it should not need them.

author: peter-h
author_rank: Super Contributor
timestamp: June 23, 2021, 01:28:46 pm
content: Just a quick Q:I am finding that the actual PCB temp is way more than what the controller is achieving according to its thermocouple sensor.On the peak (reflow) section I have 220C for 10 secs.To check the temp, with a PT100 thermometer but which has a greater mass than just a tiny TC, I extended this section to 100 secs, to give it time to stabilise.I measured over 270C! And of course there was a lot of damage to the PCB... Yet I know the oven sensor is accurate, to 1-2C. It is about 15cm above the PCB. If it was much lower, it would hit the back of the drawer lip when the drawer is pulled out.I am wondering if the profile settings in these ovens are basically "wishful thinking" and have to be "iteratively hacked" so the 10 secs is very short so as to just reach 230C for a few secs, so it just happens to work right? One would have to use a sample board and a thermocouple on it.But even the preheat platform portion of the profile (which is 130C) is measured at about 160C.

author: peter-h
author_rank: Super Contributor
timestamp: June 24, 2021, 07:25:49 am
content: Another test today, this time with a thermocouple (TC) thermometer, with a TC similar to the built-in ones.On a piece of PCB-like material, the temp seen was70Chigher.That is obviously completely useless. Clearly the built-in sensors are not picking up the effect of the IR heating.I am wondering whether a solution must involve attaching a piece of dark material, say black anodised aluminium, to the sensor(s) used by the controller?

author: peter-h
author_rank: Super Contributor
timestamp: June 25, 2021, 08:14:58 am
content: I have concluded this oven is completely useless as it is, so I am installing a fan inside.There are two versions of this oven for sale. One, which is the Puhui one, has an exhaust duct on the back. Obviously the fan in that one runs in the opposite direction, so the fumes can be extracted. But that one also suffers from an even worse temperature control, because there is close to zero airflow inside. That one has auto-opening slats, and the ES Tech replacement controller kit comes with a piece of louvred metal to replace these slats, plus they ask to turn the fan around so it runs like in the old model (but then fume extraction doesn't work). The other is the one which is all over Ebay and is a counterfeit "T962", and that has no exhaust duct, and the fan draws air into the oven.This is the Puhui one with the duct:https://www.te168.com/infrared-reflow-oven-t-962-products/This is the counterfeit one, which is practically every T962 on Ebay UK e.g. e.g.https://www.ebay.co.uk/itm/123687959494I don't think they differ internally as regards the sensor positioning, so the temperature distribution is likely to be equally useless in both.Experiments show that the colour of the PCB dramatically changes the temperature at its surface. Radiation alone is thus no good.One solution might be to mount the thermocouple used by the controller (whichever controller - the original or a retrofit) onto a piece of PCB material which lays next to the PCB. That would involve a length of TC cable flopping around inside the oven and potentially displacing any components which at that point are just sitting on solder paste. I have in fact done that with #2 thermocouple (the ES controller uses only the #1) and have it hanging out of the side of the oven, so it can be fed back through the gap around the front of the drawer, to measure whatever temperature you want to measure.So I am installing a little impeller inside. A motor outside and a 2cm diameter model boat propeller inside. Will post pics when done.I can't understand how people can sell this POS... The one way I can see it - as shipped - working and delivering anywhere near the right temp at the PCB surface is by tweaking the profile temps to be much lower than the actual numbers desired. In fact it I think it "works" for most people because running the preheat platform at say 170C instead of 130C doesn't actually damage anything (and it doesn't reach the 170C until near its end anyway) and then running the 230C bit at say 270C also doesn't damage anything because in the 10 secs or so duration of that section the PCB doesn't reach much more than 230C anyway! So it works by luck.Onedoesneed an exhaust duct otherwise every time you use the oven, it will stink out the whole room (or whole house, if at home) and it continues to smell badly for many hours afterwards. I have replaced the masking take with kapton tape, btw...

author: peter-h
author_rank: Super Contributor
timestamp: July 07, 2021, 02:04:41 pm
content: Update:I tried various ways of installing an internal fan. The tricky thing is that whatever you do has to work at 230C or more... This is the final version. The big brass cylinder has two ball bearings in its endsIt would have worked much better with a bigger propeller, so one needs to mount the shaft as high up in the drawer front as possible. This mod is very noisy but who cares...But it didn't fully fix the issues, which are basically- the mainly IR (no convection) heating produces an extremely uneven temp distribution, with 220C controller setpoint (and feedback) producing easily 290C on the PCB (the standard hack seems to be to reduce the 220C setpoint in the profile!) and even the 130C setpoint producing 170C.- if you turn up the fan a bit more, you just get cold air drawn in, which cools the sensing thermistor much more than it cools the board- the IR tubes are much too close to the PCB, so a spot under one gets perhaps 30C hotter than elsewhere.So the only way to make this cheap oven work at all usefullyif you care about the temperature to which you cook your componentsis to bring out the sensing thermocouple (the ES replacement controller uses just one sensor; no idea about the factory fitted one) on a lead and attach it to the PCB being soldered! And as you would expect, that works pretty well. Dramatically improves things -at the point where the sensor is touching the PCB.The second thermocouple is being used to measure whatever else; I used it to keep an eye on the bottom temperature which goes no higher than 150C.But one still has variations around the PCB. With the combination of sensing the PCB temperature in the middle of the PCB, and the above model boat air stirrer, it is almost usable.Another variable is the fan speed. This ovenrequiresfume extraction otherwise you stink out the whole place! So the fan has toextractair, not blow it in. I reversed mine, since the oven I got (UK Ebay) didn't have the extraction duct. I set it to just 5%, and 10% is pretty similar, with the above model boat propeller mod running to keep the air mixed. 10% gives better fume extraction, obviously. I settled on 8%. This oven has a huge hole in the bottom through which the fan draws in cold air; this is incidentally necessary to avoid the bottom of the board getting too hot. I am seeing 150C max, as stated above, which is OK. If you run the fan too fast, the heating system will be unable to reach the setpoint (say 220C).I spent way more time messing with this thing than was worth it, but at least I now have acompactoven - much smaller than the ones which actually work out of the box (and cost a lot more, like 1-2k).Since I have a second sensor I have been running tests between board centre and board edges. Due to temp variations due to poor air mixing and highly localised heating from the IR tubes which are very close to the PCB, you can't do big boards in this oven. Much smaller than the drawer size, and I reckon 12x12cm is the max which will work. However, it may be that a board big enough to cover the whole drawer bottom will also work, because it will reduce the cooling airflow around the PCB edges.Probably the best modification for this oven is a large, say 10cm dia, slow running fan, hung from above. I have seen a photo where somebody did that. It's not easy, due to a lack of space for the motor, which would need to be a "pancake" type motor. Also you would need to strip out the whole upper insulation layer to get access, which would be messy as hell.There are so many things wrong with this oven that anything it going to be hard work, unless you are happy with variations of some 30C across the PCB. I think I have got it down to the 10-20C range, which is not too bad.I am now working on a means of placing the sensor on the upper PCB surface, using some sort of spring loaded probe attached to the edge of the drawer. The obvious way is to bring the wire in from underneath, through the slots in the drawer bottom, but that needs the PCB to have a hole somewhere in it through which the sensor can come up, and then you bend it over so the TC junction sits on the upper surface. But that way it is easy to short circuit the thermocouple wires, and even touching one of them on the drawer metal produces a way-off reading (as one would expect).Another thing I will try is using a sheet of aluminium mesh above the PCB, suspended just under the IR tubes, to even out the heating.Reading some of the many threads online about T962 oven mods, it makes me smile to read all the accounts of where people burnt up various components. They obviously had no idea at all what temperature their PCB was actually reaching...This shows the TC sensor coming up from underneath, and touching the PCB upper surface. It is important to expose at least 1cm of the fine wire to the air above the PCB, but not have any of it electrically touching the drawer bottomI've just done a run and everything is within 10C. The peak temps at 220C setpoint were 224 and 211 in the centre and edge of this 10x10cm board.

author: peter-h
author_rank: Super Contributor
timestamp: July 09, 2021, 08:22:13 am
content: One correction: ref the above pic, one should untwist the thermocouple wires, so the tip is the only junction.

author: Miti
author_rank: Super Contributor
timestamp: July 21, 2021, 06:24:13 pm
content: I agree that T962 is a crappy oven. I bought a used one for $120 CAD and I did all the modifications that circulates on the internet. Well, at least the Kapton tape, the cold junction, the FW and the grounding. Moreover, I installed some sturdy standoffs to raise it up from the desk, before it catches fire.I have a temperature gradient of 10 to 20 C between the left and the right side. Also, there’s quite a difference between the temperatures indicated by its TCs and two low mass TCs attached to the board. I wanted to replace the two fixed TCs with two flexible ones that I can attach to the boards when I reflow, but after spending so much time trying to make something out of it, I lost my interest. I went back to the toaster oven and assembled few perfect boards. No controller, no burned boards or components, all manual and visually watching the temperature.

author: phil from seattle
author_rank: Super Contributor
timestamp: July 22, 2021, 03:02:36 am
content: Quote from: Miti on July 21, 2021, 06:24:13 pmThis! Every time I think about getting a "real" reflow oven, I remind myself that just eyeballing the board temp in my $10 Black and Decker convection oven has never failed me. Last week I did a 160 component 100x100mm board and it came out perfect. There is a cold-ish spot in the middle that I have to work around but I've never had to cook it at the top reflow temp for longer than the datasheet profiles

author: jpanhalt
author_rank: Super Contributor
timestamp: July 22, 2021, 09:58:13 am
content: When I was looking for a reflow oven (which is why I started this thread), I also was considering a toaster oven option. I ordered the controller from Rocket Scream in Malaysia (https://www.rocketscream.com/blog/product/tiny-reflow-controller-v2/). A short time later I came across an anxious seller for the T-962 (new, in box, $100) and bought it.I haven't seen that controller mentioned here yet and think others might find it interesting. The seller was quite prompt in shipping, but DHL was slow as can be. I think it went to Germany (Frankfurt) before coming to the US. The build is very nice, and it worked in a test rig. It may be worth mentioning that the seller was using it with a toaster oven to manufacture his products until apparently recently, when he got a Phuhui T-937M. He had problems with that similar to T-962 problems (See: comments on his site).

author: peter-h
author_rank: Super Contributor
timestamp: July 25, 2021, 12:03:39 pm
content: I doubt the controller is the main issue with these ovens. It is the temperature measurement which is rubbish. You cannot use IR (i.e. radiation) emitters, sense the temperature some 2cm above the PCB with a thin thermocouple, and expect the PCB to be anywhere near right - except by luck.I posted the mods I did above. I did two other mods:I replaced the brushless model plane motor with a Chinese fake of a smooth running Maxon motor, to reduce the vibrationhttps://www.ebay.co.uk/itm/252386889509I replaced the thermocouples (which were the same type of TC wire as originally used - grass fibre insulated) with a much thinner PTFE insulated TC wirehttps://www.ebay.co.uk/itm/383806095552which as you can see is small enough to poke up through a PCB hole from underneathThe result is dramatic, especially from using the thin wire. The measured PCB surface temp now follows the setpoint well. On the standard profile, at the 130C platform the board reaches 140C (basically the ES controller overshoots a bit) and on the brief 220C platform it reaches 225C.The propeller modification now makes very little difference, which is quite funny since I spent so much time on it

author: peter-h
author_rank: Super Contributor
timestamp: July 30, 2021, 09:12:03 am
content: I am getting good results by placing the measuring sensor on a piece of PCB, next to the PCB being soldered. That way one is not risking nudging some components when trying to place the sensor.

author: Southerner
author_rank: Regular Contributor
timestamp: November 04, 2021, 05:41:37 am
content: I was trying to find what I need to do the flash for the LPC2134 cpu in the T962 reflow oven that I have but have never tried to use. I can find the github repo for it (but it is a few years old) at:https://github.com/UnifiedEngineering/T-962-improvementsAlso this page:https://github.com/UnifiedEngineering/T-962-improvements/wiki/Flashing-the-LPC21xx-controllersupposedly tells me how to flash it. It tells me to go to:https://github.com/UnifiedEngineering/T-962-improvements/releasesto get the hex file but there is no hex file there that I could find. It does not really tell me how to make the hex file either. The wiki is here:https://github.com/UnifiedEngineering/T-962-improvements/wikiA hackaday page here:https://hackaday.com/2014/11/27/improving-the-t-962-reflow-oven/has some info but does not tell me how to create that hex file that does not appear to exist in the code (the zip file) or at the release page. I suspect that I run make or makefile but am surprised that the hex file is not already there. Or am I just missing it?I am a Windows user and running Windows 7 so I was not sure how to create that Hex file that sounds like it should already be there but I did not see it.Thank you for your help.

author: Kean
author_rank: Unknown
timestamp: November 04, 2021, 06:00:37 am
content: Quote from: Southerner on November 04, 2021, 05:41:37 amClick onAssetsto expand the list and you'll see a link to download the hex filehttps://github.com/UnifiedEngineering/T-962-improvements/releases/download/v0.5.2/T-962-controller.hex

author: jpanhalt
author_rank: Super Contributor
timestamp: November 04, 2021, 09:29:19 am
content: I used Flash Magic and an ordinary Windows PC to do the flashing with an FTDI serial cable: TTL-232R-3V3.

author: Southerner
author_rank: Regular Contributor
timestamp: November 05, 2021, 07:25:27 am
content: Quote from: Kean on November 04, 2021, 06:00:37 amI posted the question to the github page but the reply came back to look inhttps://github.com/UnifiedEngineering/T-962-improvements/releaseswhich was the link I had mentioned not being able to find the file. Later a friend told me I had to expand the Assets box to see the file. That was not clear before. Thank you all for the help.

author: Southerner
author_rank: Regular Contributor
timestamp: November 05, 2021, 07:58:18 am
content: Quote from: peter-h on July 07, 2021, 02:04:41 pmYou mention that a slower fan would be desirable. What about this slow speed motorsimilar to the one you used but only 13rpm:https://www.ebay.com/itm/122698927305Also what model boat motor prop did you use?If not, then what about cutting a vent in the side and using a tiny cage fan to push in air?Or would that be too much circulation? My concern with a mod like yours is keeping thepropeller and shaft out of the way and that is why I ask about using a tiny cage fan(if one can be found) so that it is not in the heat bay and not close to it.Thank you.

author: Southerner
author_rank: Regular Contributor
timestamp: November 05, 2021, 08:01:46 am
content: I have looked through the github page and a couple hackaday pages about T962 mods but I do not see even on the github wiki page any suggestions for which mods to do and which ones would be nice or which ones are not worth the effort. Granted replacing the duct tape with kapton tape and flashing the firmware and probably the cold temp probe I would assume would be the mods that should be done. Are there others that should be done? Which ones are not worth the effort or accomplish very little?Thank you.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 05, 2021, 08:14:56 am
content: The tape, flash, and cold junction are the three mods I did. It seems the vast majority of users has stuck to those too and seem happy with them. If you want to turn your Yugo into a Lexus, you are free to try, but they both still work for getting groceries.

author: EE-digger
author_rank: Frequent Contributor
timestamp: November 06, 2021, 02:00:57 pm
content: I've only had the T-962 for three days and also did the tape, flash and cold junction.Since I had to get a small job done, I had to create a pretty drastic profile to melt just tin-lead solder.After spending hours with this unit, I measured and noticed a number of things. One which is a killer for uniformity is that the quartz elements are much brighter at the left end than at the right. Too lazy to measure but I would estimate that the right side looks as if it were getting 50- 60% of the power.This has to be due to crappy tube construction with non-uniform wire diameter, perhaps stretched during forming (although that IS a stretch indeed).I'd like to hear other comments on the tubes. Are yours this uneven?And as another poster mentioned, the tubes are much too close to the board. I also picked up a Black and Decker toaster oven for $35 a week ago and that thing runs rings around the T-962, with my hand as the PID controller. The distance to the board is nice (and adjustable) and the tubes are highly uniform from end to end.While the T-962 is definitely cute and space saving, I don't believe that it is useful for much with the tubes I have.And, raising the board any distance other than to break contact with the floor is just an invitation for french fried substrates.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 06, 2021, 04:39:10 pm
content: I was seeing 10° to 15°C differences in temperature left to right using independent thermocouples/thermometers (see post #48). That was with a slow fan speed. After I increased that minimal speed to 20, the difference got smaller (post #49), but I didn't save those notes.

author: EE-digger
author_rank: Frequent Contributor
timestamp: November 10, 2021, 12:59:17 am
content: Since the Unified Engineering firmware exposes offsets and gains for left and right TC channels, I decided to take a closer look at these before tossing this thing out a window.With a third TC mounted between and at the same height as the chamber TCs, I adjusted the offsets on a cold chamber, then adjusted the gains with temp set to 200C. With this simple adjustment, tracking was perfect between left, right and the third TC.The real problem with IR, especially with a chamber this small, is deciding upon a reference board on which to set up a profile. Without stirring the hot air, the IR has too many variables, from reflective gold to board density (plane layers), etc.I now think the oven can be put to pretty good use, once you set up a profile based on the needs of the paste AND the characteristics of your reference board. Repeated assemblies of the same type should be a breeze, provided chamber uniformity (i.e. size) is considered.Thanks for you reply but I've gone ahead and ignored left to right delta for the moment. I think there are bigger fish to fry ... ok, bake

author: Roger_Ramjet
author_rank: Newbie
timestamp: January 10, 2022, 10:36:58 am
content: What leaded and lead free solder are people using in T962? Should you go for a low temp lead free solder to improve chances of reflowing? Thanks

author: jpanhalt
author_rank: Super Contributor
timestamp: January 10, 2022, 10:50:51 am
content: I use Kester EP256 63/37 tin/lead.I only use leaded solder and have no experience with lead-free low-temp alloys. They presumably are based on bismuth or indium and tin alloys. The former is less expensive and probably more common.

author: Southerner
author_rank: Regular Contributor
timestamp: March 07, 2023, 07:58:15 am
content: Quote from: Kean on November 04, 2021, 06:00:37 amThat github page is 9 years old. I do not see a releases page but the latest still seems to be the V0.5.2 that you linked. Is there anything newer?Thank you.

author: Kean
author_rank: Unknown
timestamp: March 07, 2023, 08:53:04 am
content: Quote from: Southerner on March 07, 2023, 07:58:15 amThe last "official" release 0.5.2 was in Feb 2008 but it works reasonably well considering the (significant) design limitations of the oven.Releases page:https://github.com/UnifiedEngineering/T-962-improvements/releasesThere are some pull requests and issues on that repo which list additional mods people have come up with. And there are 174 forks, so plenty of people have created other versions and you're welcome to dig through all of that to try find something that suits you better... but you will likely need to set up a suitable compiler and so on.

author: girts
author_rank: Contributor
timestamp: March 08, 2023, 09:15:28 pm
content: Quote from: Southerner on March 07, 2023, 07:58:15 amThat oven was designed and is sold unchanged from 2005.About SW updates on git - why? If everything works as promised?

author: Southerner
author_rank: Regular Contributor
timestamp: March 09, 2023, 08:40:03 am
content: Quote from: girts on March 08, 2023, 09:15:28 pmBecause it does not work as promised. That is why this thread is so long as many/most of us that own the T962 get temp excursions all over the map and major temperature variations depending on where you measure it inside the T962. the mods (if I read them correctly) were designed to fix that.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 09, 2023, 08:59:40 am
content: I don't believe the firmware mod was designed to fix problems with uneven heating. There are still just 2 TC's and minimal circulation in the oven. The mod allows better user control and a genuine "cold" junction correction.The mod also allows relatively easy calibration of the TC's to a reference measurement and adjustment of the heating profile. On mine, tracking of the actual temp to the profile is relatively close. Actual undershoots the peak a little, but 63/37 solder relows fine, so I haven't messed with it. Increasing soak time might help, if you are having problems. I ran a blank run before doing my boards, but I don't know whether that made any difference.Another factor is the small drawer v. big drawer version. Mine is the small drawer. I would expect more problems with the bg drawer version.