hybridfree/eevblog-posts huggingface dataset:
Remote control IR diode's resistor value - Page 1
Forum section: electronics / repair

author: sdancer75
author_rank: Frequent Contributor
timestamp: July 17, 2023, 05:35:54 pm
content: What should be the protection resistor R1 value of the IR diode of a remote control.

author: Twoflower
author_rank: Frequent Contributor
timestamp: July 17, 2023, 06:04:17 pm
content: It looks like that no resistor is required and the pads are connected by a PCB-Trace. Can you measure the resistance between the R1 pads?As the remotes usually use very short pulses the battery + transistor internal resistance is enough to not damage the LED. Plus over lifetime of the remote the LED is active maybe only in the range of minutes.

author: fant
author_rank: Contributor
timestamp: July 17, 2023, 08:23:56 pm
content: If battery voltage is 3 V, usually it span from 1 to 1,8 Ohm.Mandi

author: sdancer75
author_rank: Frequent Contributor
timestamp: July 18, 2023, 06:17:53 am
content: Quote from: Twoflower on July 17, 2023, 06:04:17 pmThe resistance between R1 pads seems to be infinitely.... I will recheck it. The pads oxidized because water dropped, and I cleaned them with isopropyl alcohol.I will measure them again and I will let you know.

author: Twoflower
author_rank: Frequent Contributor
timestamp: July 18, 2023, 06:26:47 am
content: It is hard to see on that picture (even if the images have very good quality) if the traces are corroded away. Especially the trace to the pad close to the 1 of R1 looks suspicious. Probably it‘s a good idea to check the traces and pads that are not protected by the soldermask closely.It would be very odd if a resistor disappears leaving no traces. And the pads don‘t look like there was a part soldered.

author: Shonky
author_rank: Frequent Contributor
timestamp: July 18, 2023, 06:32:04 am
content: Definitely not fitted by default from those pictures. Check for continuity from either side of the resistor and bridge if there is none - looks like near the 1 in R1 there is no track.

author: sdancer75
author_rank: Frequent Contributor
timestamp: July 18, 2023, 06:10:55 pm
content: The continuity between pads was problematic. Using my microscope, I noticed that both pads were discontinued from their main rails left and right, by the oxidation they had. So, shortcutting externally the two points resolved the problem. Remote control works again.Thanks to all guys.
Remote thermo/humid sensor disconnecting - Page 1
Forum section: electronics / repair

author: justaguy
author_rank: Contributor
timestamp: August 24, 2023, 07:12:13 am
content: I have a TFA-Dostmann weather station that has worked fine for years, but recently started to suffer from random disconnects with the external thermo/humid sensor.When the signal is lost, the only way is to reset the base station and then it works for some days, before disconnecting again.Of course could be just random RF noise from the neighborhood, but I think some component may have degraded over time (it´s about 10 years old).I have checked the obvious on both TX and RX sides, but unfortunately I lack RF tools (and experience); I only have a 100MHz scope and a RTL_SDR compatible dongle. With that one, I confirmed the transmitter is sending out pulses at levels comparable with other transmitters at about 433.85MHz.On the receiving side I don´t really know what to check...I´m wondering if the oscillator in the RX module needs to be tuned, and how can I do that with the limited equipment that I have?Any brilliant idea before I toss it in the bin?

author: CosteC
author_rank: Regular Contributor
timestamp: August 24, 2023, 09:22:46 am
content: Batteries are obvious thing, but those you probably checked.De-tuning 433 TX or RX is an option. Probably more TX as it is outside, exposed to elements.on photos I do not see corrosion, so it shall be fine.Maybe your dongle can measure up to 433 to check frequency?

author: justaguy
author_rank: Contributor
timestamp: August 24, 2023, 09:58:45 am
content: Yes, with the dongle I see the TX signal at about 433.85MHz. Playing with the variable inductor on the TX module moves the frequency up and down by about 50KHz and the power up and down a bit, I tried to tune it where the signal seems to come out stronger but it´s far from an accurate measurement.Batteries have been replaced.

author: CosteC
author_rank: Regular Contributor
timestamp: August 29, 2023, 06:42:47 am
content: Quote from: justaguy on August 24, 2023, 09:58:45 amUnfortunately you need to tune it to receiver frequency not to maximum power. Not sure can it be done other way than blindly adjust to see receiver receiving.. Maybe RF people can help?
removable threadlocker - Page 1
Forum section: electronics / repair

author: cncjerry
author_rank: Unknown
timestamp: November 06, 2024, 06:30:22 am
content: Hi, what is the blue threadlocker used on computers screws, etc that is removable? I've looked at loctight blue medium but that seems to be too permanent.ThanksJerry

author: coppercone2
author_rank: Super Contributor
timestamp: November 06, 2024, 06:40:24 am
content: violet

author: indeterminate
author_rank: Regular Contributor
timestamp: November 06, 2024, 08:45:59 am
content: Loctite 222, Screw Lock Low Strength
Remove covers from HP 4123A Duplexer for HP 4050 printer - Page 1
Forum section: electronics / repair

author: perdrix
author_rank: Frequent Contributor
timestamp: November 05, 2023, 02:23:18 pm
content: I did this some years back to re-tension some springs to prevent paper jams. The springs just needed a gentle squeeze to restore normal service.Now I want to remove the covers to do this again, but am clearly suffering from brain fade as I can't remember how to remove them without breaking things.What's worse I'm sure I found a website last time round that gave excellent directions for this, but my google fu has clearly deserted me as I cannot find it now.If anyone knows how to do this or better knows where to find a webpage with pictures showing how its done please let me know****I eventually worked out how to get them off there are clip points on the top, front and rear all of which need to be gently pried open.ThanksDavid

author: jonpaul
author_rank: Super Contributor
timestamp: November 05, 2023, 08:03:30 pm
content: Google is now a sales vehicle and not a valid search anymore.We use duckduckgo.Best info: Go to HP printers forum.The 4050 OP and SERV manuals are easily found.J
Removing a QFN13 chip - Page 1
Forum section: electronics / repair

author: R-1125F
author_rank: Regular Contributor
timestamp: February 27, 2025, 10:12:06 pm
content: I just had to struggle getting a QFN13 chip off the board. I had not done this before so I was uncertain about the temperature and airflow. I am using an ATTEN ST-862D for hot air. I had it set at about 380C and 50% air flow. Could someone tell me what temperature and airflow that I should have used that would make it easier next time?

author: MathWizard
author_rank: Super Contributor
timestamp: February 27, 2025, 10:37:17 pm
content: IDK what temps are really good, or airflow yet either. If my flux is starting to smoke and stain the board, I get nervous. Lately I'm using 350C on a clone 858D, and I'm not scorching the PCB anymore, so I'm getting better at it.But did you use lots of flux, and heat the PCB around the outside of the chip, more so than on the chip ? Slow and steady is what I do, and with big ground planes, etc, it can take a while, but yeah I'm not burning PCB's or as much flux anymore.

author: R-1125F
author_rank: Regular Contributor
timestamp: February 27, 2025, 10:38:52 pm
content: I used lots of flux but I probably should have used a preheater too. I have one, but I didn't use it.
Removing cemented on SMD chips - Page 1
Forum section: electronics / repair

author: Audiorepair
author_rank: Frequent Contributor
timestamp: October 30, 2020, 08:42:42 pm
content: I tried to remove an unavailable IC from a donor board to fit onto another board.(28 pin DIL SMD)Trouble is, the IC's are glued onto the PCB, and after a huge amount of hot air, it still wouldn't dislodge.Eventually I gave up as probably having destroyed the chip, and lifted every pin, when I was then able to chisel the IC off the board, revealing the 2 blobs of cement.How could you possibly get such a glued chip off the board without damaging it?

author: ambrosia heart
author_rank: Regular Contributor
timestamp: October 31, 2020, 12:27:23 am
content: Use them. Despite expensive, it is worthy and trustworthy for tech to own. Hot air gun lifts off pads if temp is too high or too low. An authentic BGA rework station avoids this situation. When reflow curve reaches max on screen, tech removes chip easily.

author: wraper
author_rank: Unknown
timestamp: October 31, 2020, 12:37:59 am
content: Quote from: Audiorepair on October 30, 2020, 08:42:42 pmHeat it until solder melts. Then rotate it with pliers instead of trying pulling it up. Breaking adhesive by shearing is much easier. It's best to use hot air in combination with preheater so solder does not solidify at the moment when you stop blowing hot air to use pliers.

author: wraper
author_rank: Unknown
timestamp: October 31, 2020, 12:40:49 am
content: Quote from: ambrosia heart on October 31, 2020, 12:27:23 amDid you ever do any rework to claim this? Removing small chip with such IR station is not only way more difficult but is also more damaging to PCB. Do you not see "BGA" in the title?QuoteReally? Please explain this magical mechanism by which IR station undoes the adhesive.

author: amyk
author_rank: Super Contributor
timestamp: October 31, 2020, 12:45:37 am
content: If you are not interested in saving the board, then turn it over and mill it out from the back.Don't remove the chip from the board, remove the board from the chip

author: _Wim_
author_rank: Super Contributor
timestamp: October 31, 2020, 08:49:50 am
content: Quote from: wraper on October 31, 2020, 12:40:49 amI have on off these. I agree these do not help for a cemented chip, but these are also not only useful for BGA. To remove large chips with many pins (like for example DSPs) they are already really handy. For smaller chips I have the bottom section only as a pre-heater, and use a normal hot air station on top.As explained above, twisting instead for cemented chips is a good option. If possible, try to use a pre-heater together with a hot air gun, it makes life easier. Any cheap pre-heater solution will do.
Removing Cover from NAD D3020 V1 - Page 1
Forum section: electronics / repair

author: Angus814
author_rank: Newbie
timestamp: July 04, 2023, 06:01:39 pm
content: My due diligence of searching online for an answer to my problem has landed me here at the EEV Blog. I am impressed by the amount of knowledge gathered on one site.I have enjoyed years of service from my NAD D3020, that is until I dropped it while rearranging my studio furniture. Now, the lights are on, but no one is answering the bell. Lesson 1: Always disconnect electronic equipment from its power source before moving the table on which they sit. I found a clue as to where the other screws for the outer case were located by visiting this site. They seem to be located under the NAD label. The metal label appears to be glued on very well and is recessed in the rubber side cover, thus making it almost impossible to slide a blade under it to lift up. Does anyone (reading this) have experience in D3020 disassembly? If so, could you share your tips on removing the label? I would be much obliged for your assistance.

author: mario_nks
author_rank: Contributor
timestamp: July 19, 2023, 11:03:28 am
content: Hello,the screws are not on the Label in your Photo. The Screws are under the label in the back of the Unit where the Speaker Terminal, RCA,.... located.best regardsMario

author: simba15
author_rank: Regular Contributor
timestamp: July 20, 2023, 02:58:17 pm
content: Service manual attached.First link shows how to remove the side cover (as Mario_nks stated) , others are some pictures of open devices and another repair thread.https://unbarthefoo.blogspot.com/p/add-power-on-led-to-nad-d-3045.htmlhttps://www.eevblog.com/forum/repair/help-repair-a-d-class-amplifier-nad-d3020-v1/https://www.connect.de/testbericht/nad-d-3020-test-vollverstaerker-1896564.htmlhttps://www.hifinews.com/content/nad-d-3020-v2-amplifier-page-2
Removing hard sticker residue and stainless rust - Page 1
Forum section: electronics / repair

author: Shock
author_rank: Super Contributor
timestamp: April 06, 2020, 02:14:20 pm
content: Here is a couple of restoration cleaning tips I've used recently. Obviously use at your own risk and test out on a small area first.For removing hard sticker residue with traces of paper left I found that any abrasive type rubbing can mess the surrounding finish. Instead of using something like goo gone, I found that a small ball of paper towel soaked in warm water with a dab of kitchen dish washing detergent works. You apply it the same way you would use a poultice to a wound. It sticks in place and keeps the detergent on the spot while the warm water also helps soak the area. Use clear detergent if the finish is at risk of being stained by the dish washing detergent.For removing soft stickers I found if the sticker area is warmed slightly and you remove the sticker very slowly then the residue will break away from the surface. You can also reapply the sticker and slowly lift it off again or use another sticker as extra adhesive pulling power.For removing stainless rust and a mild oxide abrasive cleaner, wet ball of paper towel and dip it in a little baking soda (bicarbonate of soda). The baking soda is too abrasive for a mirror finish on some surfaces so afterwards use plastic, stainless or glass polish if requiring a high polish. Baking soda does leave a residue so will need to be cleaned off with a little water or whatever is compatible with your surface.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: April 06, 2020, 03:58:58 pm
content: To remove non-dissolvable gooey label residues which are also resistant to warmingI use double sided carpet sticky tape. Apply several times on the gooey spot removinga bit of goo each time until it is all gone, i.e sticking to the sticky tape.

author: Shock
author_rank: Super Contributor
timestamp: April 06, 2020, 08:07:49 pm
content: Yes I've done that as well, not specifically with carpet tapes but others. Turpentine which is a cheap solvent oil also works on large areas if the surface is hard, non porous and not prone to melting. Then remove the turpentine with a detergent.
Removing microrprocessor - Page 1
Forum section: electronics / repair

author: laispais
author_rank: Newbie
timestamp: May 08, 2023, 06:39:33 pm
content: How do I get off these processors? (Y1)https://imgur.com/a/1PGSa5c

author: wasedadoc
author_rank: Super Contributor
timestamp: May 08, 2023, 06:44:36 pm
content: I don't understand the top photo.The second one is Chip-on-Board. Not really removable, especially if you want to re-use it.

author: Kosmic
author_rank: Super Contributor
timestamp: May 08, 2023, 06:48:49 pm
content: On both pictures Y1 look like a crystal/oscillator. Just use hot air and flux.

author: wasedadoc
author_rank: Super Contributor
timestamp: May 08, 2023, 07:24:49 pm
content: Quote from: Kosmic on May 08, 2023, 06:48:49 pmNow I see. Thanks. Not "processors".
Rems camscope, not transmitting image over wireless - Page 1
Forum section: electronics / repair

author: masterx81
author_rank: Frequent Contributor
timestamp: June 15, 2020, 07:44:07 pm
content: Hi!I have a rems camscope (an endoscope camera with detachable display module) that not send the image when phisically disconnected from the camera gun.Afaik it transmit in the 2.4hhz band. There is a way to see if is failed the transmitter unit or the receiver unit?The receiver unit have 4 channel to select, but i not get any image in any of them. I think that the channels are here to match the monitor with different camera guns, but i've not see any way to set che channel on the camera body.I not have anything that can measure an "over ghz" frequency.Any ideas?
Repair 12v Camping Style Battery Box - Page 1
Forum section: electronics / repair

author: secondlife
author_rank: Newbie
timestamp: February 01, 2022, 06:34:17 am
content: Hey All.Looking for a little help in how to locate what may be causing the issue with my Arkpack Battery Box causing it to display approx 0.7V less than the confirmed battery voltage. I have been unable to locate schematics for the unit and have had to delve into the world of digital electronics further than I have previously. My past repairs have not been in the microcontroller space and I am starting to get the feeling this may be the issue here,First I am making a few assumptions. a) That this device is using a shunt off the main battery supply to determine the voltage and b) given the shunt seems to follow the usual U shaped wire type and its resistance as close as I can tell is correct at 0.1Ohms.I have checked all the resistors that look like voltage dividers and all check out OK but given it seems the magic is happening on the silicon and I have no idea what pin is for what its hard to know where to from here. I have included a pic of the board for reference but an ideas on next steps would be welcome.Link to the product:https://www.bcf.com.au/p/ark-arkpak-730-power-battery-box/373115.html

author: geggi1
author_rank: Frequent Contributor
timestamp: February 01, 2022, 06:05:08 pm
content: To me it sounds like it might be that the voltage is measured on the wrong side of a diode.When a diode is conducting you will have about 0,7V over the junction.Look at the beefy diodes like D1 and D11 if one of them are in the output path of the battery you have the reason there.

author: TheMG
author_rank: Frequent Contributor
timestamp: February 02, 2022, 12:02:14 am
content: Is it just me or does the polyfuse (F3) look like it has taken some damage?

author: fzabkar
author_rank: Super Contributor
timestamp: February 02, 2022, 12:13:59 am
content: Quote from: TheMG on February 02, 2022, 12:02:14 amAgreed, and there looks to be a TVS diode (SMCJ5.0A-TR, FUA) adjacent to it.https://www.jameco.com/Jameco/Products/ProdDS/1395796.pdf
REPAIR: 33250A incomplete square wave waveform - Page 1
Forum section: electronics / repair

author: ThaiGuy
author_rank: Newbie
timestamp: August 11, 2022, 07:19:24 am
content: I recently got a 33250A, everything is working fine except for the square wave waveform. Anyone encountered this problem before or any one have idea on how to fix it. Thank you in advance

author: MegaVolt
author_rank: Frequent Contributor
timestamp: August 11, 2022, 09:14:44 am
content: What is the signal source? Have you tried signaling from another source?

author: HighVoltage
author_rank: Super Contributor
timestamp: August 11, 2022, 09:17:26 am
content: did you set the scope and 33250A generator to 50 Ohm?

author: coromonadalix
author_rank: Super Contributor
timestamp: August 11, 2022, 10:58:32 am
content: and please do not double post in different sections

author: wasedadoc
author_rank: Super Contributor
timestamp: August 11, 2022, 12:26:09 pm
content: Quote from: MegaVolt on August 11, 2022, 09:14:44 amThe 33250A is the source. It is a waveform generator.

author: wasedadoc
author_rank: Super Contributor
timestamp: August 11, 2022, 12:31:10 pm
content: Quote from: HighVoltage on August 11, 2022, 09:17:26 am1. It is a 1kHz signal. Source and term impedance will have negligible effect.2. Even at higher frequencies, source and term impedance issues alone do not cause asymmetric distortion.

author: TheSteve
author_rank: Unknown
timestamp: August 11, 2022, 02:10:48 pm
content: You will want to work your way through the troubleshooting focusing on the ECL logic.

author: wasedadoc
author_rank: Super Contributor
timestamp: August 11, 2022, 04:55:11 pm
content: Looks like an analogue fault to me.Change the generator frequency to 5 kHz and change the scope timebase to 100us. If the waveform shape still looks exactly the same then start by assuming a digital fault. If the waveform shape/amplitude is different, suspect a problem from the output of the DAC onwards.Service manual with schematics:http://ridl.cfd.rit.edu/products/manuals/Agilent/function%20generator/33250-90011_service_guide.pdfPage 203. U1904 pin 22. Waveform Ok or not? If yes, there isn't much between that point and the final output.If no, see Page 201. The DAC (MAX555CCB) is the large square at top left. Output goes to pin 3 of the relay and thence into one or other of the two filter networks. Appropriate filter output is at pin 8 of the relay. OK or not there?If not then a digital fault or faulty DAC/surrounding components. If yes follow the analogue path through towards U1904. Check supply voltages to all the ICs in the path and to all the clamp/protection diodes.
Repair a Delongi CF08E dehumidifier sllllooooooowwww fan - Page 1
Forum section: electronics / repair

author: bytes
author_rank: Newbie
timestamp: June 18, 2025, 08:29:59 am
content: Hello. Any first thoughts on the issue that may be causing the fan in my dehumidifier to play up.When you first turn it on, it starts spinning up like it normally would to a good fast speed. After a second however slows down and it starts crawling: about one rotation every 5 seconds. No bad noises. A little bit of a 50Hz hum, but it always has had one. Compressor is still working fine. I took it apart and the fan is easy to spin, so it doesn't seem to be seised. The motor is a 4 pole 220V motor. It has 240Vac between red and brown and ~60Vac across red and black. Electronics look fine. Any suggestions? Thanks

author: cozza
author_rank: Regular Contributor
timestamp: June 18, 2025, 08:23:50 pm
content: Looks like the grey motor run cap below the motor has failed from the photo. Or if that's not a bulge out the side, check the black 1uF cap on the PCB. Motor appears to be a multi speed unit
Repair a DPS5005 PSU - Page 1
Forum section: electronics / repair

author: kakas
author_rank: Newbie
timestamp: October 02, 2021, 12:09:46 pm
content: I switched on my unit with a load on the output. Input voltage was 50V, output set to 5V, load was appr. 3 amps.I do not know what went wrong, but the U1 with 6 pins marked in the picture burned. Since then it always outputs the input voltage.Can someone tell me the ID of this component? Thank you.
Repair a Metrix AX502 bench power supply - Page 1
Forum section: electronics / repair

author: Lycias
author_rank: Newbie
timestamp: March 04, 2020, 09:28:55 pm
content: Hi,I’ve recently acquired a Metrix AX502 bench power supply.Documentation is available:https://catalog.chauvin-arnoux.com/fr_en/ax-502.htmlThis power supply has two variable outputs (0 to 30V, 2.5A): “master” and “slave”.The “slave” output is working as expected. However, the “master” output is faulty.When rotating the potentiometer, the output varies from 150mV to 1.65V approximately, instead of 0V to 30.5V, according to the specifications. Also, the screen doesn’t display voltage and current as expected, but only the decimal dots.I’ve started to investigate the issue. So far, I haven’t noticed any faulty components, but I’ve noticed the voltage is incorrect at various places. I have yet to disassemble the two circuit boards.Unfortunately, I failed to obtain schematics from the manufacturer (Metrix / Chauvin Arnoux).Would anyone familiar with linear power supplies could provide some advice about the possible causes of this issue?Failing "master" output, potentiometers to minimum:Failing "master" output, potentiometers to maximum:Working "slave" output, potentiometers to minimum:Working "salve" output, potentiometers to maximum:External views of the power supply:Top view of the power supply:Thanks.

author: Lycias
author_rank: Newbie
timestamp: March 04, 2020, 09:44:48 pm
content: Here is a description of the different parts of the main circuit board:

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 04, 2020, 10:47:47 pm
content: First start checking that all the DC voltages after diode bridges are present.Considering there is no display on the master panel meters I would look at what IC's are used for that function and if they are getting correct power, this and the no output symptoms would make me expect that you're lacking a +/-12V supply somewhere.Your photos show a bare / burnt / corroded trace on the front PCB behind the slave output. Have you checked on that? If it is corrosion take a look at the hidden side of the front PCB.

author: tunk
author_rank: Super Contributor
timestamp: March 04, 2020, 10:58:24 pm
content: Disclaimer: I don't know much about PSUs.That said, it looks like they are (almost) identical:- are the outputs from the transformer the same.- are the resistances of the potentiometers the same.- there is a device under a folded metal heatsink whichcould be switching between the transformer windings.Does it work? (Don't ask how to check.)Also, if you connect e.g. a 100ohm resistor, does it stillshow 150mV to 1.65V?

author: goaty
author_rank: Regular Contributor
timestamp: March 05, 2020, 09:33:21 am
content: Maby also check (low voltage) power supply for display and opamps (like 7812 linear regulator) which could be gone bad.
Repair Advice Needed: TMS 320f2812pgfa getting hot  - Page 1
Forum section: electronics / repair

author: fkfaraz
author_rank: Regular Contributor
timestamp: July 13, 2022, 07:30:03 am
content: Hello I hope you All will be Fine.So I have a microprocessor board(kind of CPU for the Whole System) in which the Processor is Texas Instrument TMS320F2812PGFA. This processor is getting hot when we turn the power on. Below Please find the Datasheet for the Processor.https://www.ti.com/lit/ds/symlink/tms320f2812.pdf?ts=1657675515389&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTMS320F2812Now my question is i want to change it, but i am confused, do i have to programmed it too or just replace it. As there is an ATMEL EEprom on the board with intact Firmware(i Suppose).I don't know much abt the controllers and Processors, but my guess is if an separate EEprom is used, then there would be no code or firmware in the processorI am Sorry if i did not conveyed my thoughts exactly, English is not my Primary language...

author: m k
author_rank: Super Contributor
timestamp: July 19, 2022, 01:53:47 pm
content: New one is empty.So yes, you have to program it.It's also very likely that the software is not available.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 19, 2022, 04:53:52 pm
content: Yes the FLASH of a new processor will be empty.Was the system still somewhat working? If the FLASH of the original is still in tact and not locked it might be possible to extract the code with JTAG.If it is locked or the processor is fully dead then you are out of luck and need to contact the company who made the board.An EEprom is normally only used for some parameter storage and not firmware, due to them being small in memory size and lack of speed.
repair Agilent E4402B Tracking Generator 3GHz - Page 1
Forum section: electronics / repair

author: m2012
author_rank: Newbie
timestamp: January 15, 2025, 08:56:57 pm
content: I have a tracking generator in my E4402B that was flooded with water.The BITG is a new type 5086-7993. I don't have any output level at all.Inside the BITG is pure horror for anyone who wants to carry out an effective repair.I cannot repair the output board in the BITG. This is because even if I had a machine forbonding gold wires, it would be very difficult to buy components without a housing.That's why I decided to recreate the BITG.There was another post that was about a BITG for an E4407 that was built on normal PCB material.I think there are probably other people withthe same problem.

author: m2012
author_rank: Newbie
timestamp: January 23, 2025, 11:23:55 am
content: So, here are some photos of my defective output board.You can see that some open wafers were installed and wired. Even the capacitors were not soldered.

author: m2012
author_rank: Newbie
timestamp: January 23, 2025, 11:52:03 am
content: Ok, then I'll get started. I have a BITG circuit diagram herewhich was originally created by dj9ss.I have solved some unclear points and added some component values ​​from parts of my BITG. The schtplan initially only contains the RF part. I start with the control when the RF works.I still need some help calculating the missing component values. For example, there is a filter L7 L8 L9 on page 4 and the frequency multiplier also on page 4.Then there are the FL17 on page 4 and both filters on page 5 of the FL1 as structure on the pcb. Another point that comes to mind is the 1GG5-4202.it is a diode-based reverse power limiter. There are probably other manufacturers that make a similar product.

author: m2012
author_rank: Newbie
timestamp: January 24, 2025, 10:46:16 am
content: Today I have a few measurements in my luggage. These are the parts of my BITG that still work well. All measurements were carried out with a 20dB adapter.
Repair Agilent N5172B - Need support fined unknow IC component - Page 1
Forum section: electronics / repair

author: chinhcheng
author_rank: Contributor
timestamp: September 01, 2022, 04:13:55 am
content: Hi AllI am a newbie here, I am repairing Agilent N5172B in a local company in VietnamService Engineer said to me that it broken unknow IC, with code G406 (that attached in Main board), please see image, but he don't know how to buy itIs there any body know this. Please help me to know where I can buy this IC.Thank you so much in advance.Modify message

author: fzabkar
author_rank: Super Contributor
timestamp: September 01, 2022, 05:35:12 am
content: The logo looks like Siliconix (Vishay). I thought it might have been a DG406, but that chip has the wrong number of pins.Edit: I think it's a DG408.DG408DQ, Siliconix / Vishay, 8-channel single-ended analog multiplexer, 44V, TSSOP-16:https://www.vishay.com/docs/70062/dg408.pdfhttps://www.ebay.com/itm/392526889484

author: chinhcheng
author_rank: Contributor
timestamp: September 02, 2022, 09:59:09 am
content: thank you so much Sir, I will check it

author: gamalot
author_rank: Super Contributor
timestamp: September 02, 2022, 10:59:00 am
content: Quote from: fzabkar on September 01, 2022, 05:35:12 amI second.Actually you can even find DG408DQ with G406 on it just like the one in OP's pictures.

author: chinhcheng
author_rank: Contributor
timestamp: September 02, 2022, 04:32:39 pm
content: Wow,Thank you so much for your information, Gamalot
Repair Agilent N9010A - Need support find 120 ohm resistor - Page 1
Forum section: electronics / repair

author: chinhcheng
author_rank: Contributor
timestamp: September 01, 2022, 03:49:30 am
content: Hi AllI am a newbie here, I am repairing Agilent N9010A in a local company in VietnamService Engineer said to me that it broken resistor with value 120 ohm (that attached in an Attenuator Part), please see image, but he don't know how to buy itIs there any body know this. Please help me to know where I can buy this resistor.Thank you so much in advance.

author: Mario87
author_rank: Frequent Contributor
timestamp: September 01, 2022, 07:32:57 am
content: 2nd image looks like you have 3 of these resistors in parallel with an empty space at the top where I assume the broken one should sit.How was the resistance measured? Did the service engineer take out each resistor and measure individually or did they just measure from 1 side of the 3 resistors in parallel to the other side? With 3x resistors in parallel 137.4 ohms would be 412.2 ohms per resistor which means you are really looking at a 412 ohm resistor with probably a 0.1% tolerance level412 ohm SMD resistors should be a bit easier to find from the usual sources.

author: chinhcheng
author_rank: Contributor
timestamp: September 02, 2022, 10:11:26 am
content: Hi Mario87Thanks so much for your response, you true,He just checked it again, in the first picture, it is 4 x 120 ohm registor for level atennuator is 10 dBThe other attenuator level is 6 dB, 20 dB, 30 dB are not as bad as failure, but there is error.

author: chinhcheng
author_rank: Contributor
timestamp: September 04, 2022, 06:48:35 am
content: Up!

author: chinhcheng
author_rank: Contributor
timestamp: October 04, 2022, 08:00:35 am
content: These resitor is a component in below attenuator,PN: 3321-6080-64-1305-V10352

author: HighVoltage
author_rank: Super Contributor
timestamp: October 04, 2022, 08:36:28 am
content: I would assume that these resistors are made and trimmed by Agilent or some special supplier to Agilent.You will not be able to get exact this resistor as a replacement part.You may use other resistors and trim to your needs.But it will no longer match the original specifications.

author: chinhcheng
author_rank: Contributor
timestamp: October 06, 2022, 12:21:47 pm
content: HiTks so much for your information, in this case, the solution is find another attenuator on ebay((

author: qnhn90
author_rank: Contributor
timestamp: October 07, 2022, 06:57:55 am
content: bạn tìm đc linh kiện chưa?
Repair amd sapphire nitro r9 390 - Page 1
Forum section: electronics / repair

author: Mat2786
author_rank: Newbie
timestamp: April 28, 2021, 11:31:38 am
content: Hello all i have problème with my r9 390 sapphire nitro.Can you help me?I have Black screen and no boot.I have tested all Voltage and i have no Voltage to vmem.And two capacitor.After other test i connect power supply 2 mosfet 4c10n have 12vAnd 2 mosfet 4c10n 0v fuse 0v capacitor 0v see picture.Thank you
repair and restoration HP 1610A Logic State Analyser   - Page 1
Forum section: electronics / repair

author: Teichhermelin
author_rank: Regular Contributor
timestamp: December 29, 2022, 11:00:06 am
content: I'm trying to bring this good old piece back to life. I have now received the service manual from the USA and can therefore start the repair. But first the CRT is on the agenda. I have to get rid of the glue first.I try to provide you with updates whenever I have time and desire.Here is the current status...

author: Stray Electron
author_rank: Super Contributor
timestamp: December 29, 2022, 04:55:07 pm
content: That CRT looks like it might not be usable. Those old HP CRTs often developed mold(?) between the front of the CRT and the bonded on safety shield. I had a bunch of HP 64000 development systems that did that and think the CRT was made by the same people, "Clinton Electronics", IIRC.That band around the CRT in your's should not be rusted like that. Somebody has stored that unit in a damp location.

author: Teichhermelin
author_rank: Regular Contributor
timestamp: January 01, 2023, 08:56:26 pm
content: The pane has to be removed, that's clear. I'm still debating which method to use. Either water/vinegar or a heat gun. But I tend to go with water/vinegar first.

author: factory
author_rank: Super Contributor
timestamp: January 02, 2023, 01:31:30 pm
content: Quote from: Stray Electron on December 29, 2022, 04:55:07 pmLooks exactly like the 1610Bthat was on ePay in the UK, the stickers & mold are identical.https://www.ebay.co.uk/itm/185283976884The mold and lack of pods with it, put me off buying it, however the rest of it doesn't look bad from the outside.A lot of vintage electronics in the UK is rusty, corroded, etc, houses are small over here and stuff got abandoned for decades in crappy leaky/damp sheds/garages/attics, sadly not much we can do about it.Never heard of Clinton CRTs, wonder if they actually made it, or if it's a rebrand. Is it glued together like some old TV CRT safety lens were in the US? The method of removal varies depending on the glue used by different brands, would be a summer job over here to avoid getting moisture trapped when reattaching it.David

author: Pointyhead
author_rank: Newbie
timestamp: March 22, 2024, 06:42:45 pm
content: Did you get it repaired?BTW, the CRTs were in fact made by Clinton.
Repair APC Back-UPS ES 750VA, model BE750G, CRISPY! - Page 1
Forum section: electronics / repair

author: Tim88
author_rank: Regular Contributor
timestamp: December 12, 2021, 06:08:27 pm
content: I have four of this model backups, seemed to work well, just replace the batteries every few years. Two days ago, my computer just went blank, the APC beeped and I was like wth? Had put a new battery in a couple months ago. I figgered something was going wonky with the electrical innerds. So I decided to pull out my spare unit and have a look see at the board to ready myself for the one attached to my puter. To my surprise, C7(330uF 25V) cap was bulged and two SMD resistors were toasty.The ground lead of the cap goes to a 1Ω resistor then to a .75Ω resistor on to ground.Amazingly, the traces running under those resistors ohmed out good so gonna shoe in through hole replacements and see if she works.My question is, do those resistors act like a fuse supposedly to protect the circuit and why two in series? I opened up my puter backup unit and that cap was bulged, fortunately no fire and tests 28pF. Wondering if there is a better way to design this with maybe a fuse?Thanks!

author: tkamiya
author_rank: Super Contributor
timestamp: December 13, 2021, 04:08:57 am
content: It's impossible to say exactly without having access to schematic diagrams. But I'd think if they wanted circuit protection, there are better ways. My GUESS is, together, they form a time constant for something. Also my GUESS is, cap has failed in short mode and current was dumped right into 1.75 ohm total. It's easy enough to replace those 3 components. I'd try that if it were mine.

author: TheMG
author_rank: Frequent Contributor
timestamp: December 13, 2021, 04:02:21 pm
content: Resistors are likely for current sensing or something like that. Without any context as to what part of the circuit it's in and what the purpose of the circuit is, hard to say, but pretty sure those resistors aren't in there for protection/fusing purposes.Could this be part of the battery charging circuit perhaps?
repair aps 9501 - Page 1
Forum section: electronics / repair

author: phoenix1988
author_rank: Newbie
timestamp: December 20, 2019, 10:21:33 pm
content: Hallo zusammen. Ich habe ein Problem mit elektronische Gerat (APS-9501 Das ist Labornetzteil) und ich brauche eure Hilfe. Diese Gerat hat andere Eigenschaften: 220V ac 2 amp und 110 V ac 4 amp. Mein Probleme ist, dass: ... Wenn ich diese Gerat zu Rheostat anschlissen seine Eigenschaften ist richrig, aber wenn ich diese Gerat zu der elektronische Last anschliessen, seine Eigenschaften entsprechen nicht. Ich kann nicht diese Problem verstehen , ich habe kein Schaltplan.Wenn gibt es ein Moglichkeit, sagen mir bitte, ist es moglich diese Schaltplan finden? Vielen Dank.

author: Echo88
author_rank: Frequent Contributor
timestamp: December 20, 2019, 10:38:24 pm
content: Hi,ich habe keinen Schaltplan für das APS-9501 gefunden und vermute das der Hersteller es auch nicht veröffentlicht hat.Eventuell ist deine Elektronische Last nicht für Wechselspannungsquellen geeignet oder hat Probleme mit dem APS-9501, da es ja mit dem Rheostat als Last funktioniert? Bitte nenne den Typ der Elektronischen Last.Eventuell können die anderen Forennutzer besser helfen; ich übersetze deine Frage für das Forum nochmal auf Englisch:I translated the german question of the TO, since you guys might be able to help him better this way:"Hi, im having a problem with my APS-9501 AC-Source. When loaded with a rheostat its working fine, but connected to my electronic load its having problems. Can someone please provide the schematics of the APS-9501, if available? Thanks"

author: Simon
author_rank: Unknown
timestamp: December 20, 2019, 11:17:29 pm
content: Can we stick to English please

author: Alex06
author_rank: Contributor
timestamp: December 28, 2019, 09:53:36 am
content: Have you tried to interchange the terminals on the source Aps-9501
Repair attempt on a Voltech PM300  - Page 1
Forum section: electronics / repair

author: JAH981
author_rank: Unknown
timestamp: February 26, 2016, 04:47:36 pm
content: Hi,Just wanted to share my attempt on repairing a Voltech PM300 since there is very little information on this bit of test gear.For just over a year ago I posted a question about aweird faultI had on my PM300. Dave's teardown of similar unit is in. I even posted a similar post on voltechsown forum. After this I got in contact with Voltech support service and got a quote for repair and calibration, which was way to expensive for me to warrant the cost for hobby usage. (I guess the price was resonate at a professional level but not for a hobbyist) (It is also a nightmare to ship stuff from Norway to the UK and back due to Norwegian customs...)The unit has just been sitting on the shelf for around a year and until I found time to have a go at fault finding on it by myself. After a lot of searching on the internet I kinda gave up on finding a service manual or a circuit diagram for it. But since it has three identical channels it means that I can measure on a working channel to get a known reading to look for.I must say that the design does make fault finding a lot harder, it it really hard to probe inside the unit when all PCBs is mounted together. The fault was also on the channel on the bottom card, which makes it even worse to get to.After a bit fiddling with reading the data sent over the three optocouplers (Seems like one is for clock, and the two other is TX and RX) I found out that the controller was not receiving anything from the isolated channel. Probing around on the ADC and the shift registers, I quickly realized I had forgot rule number two: "Thu shall measure voltages." 5V rail was dead. The 2-stage transformer gives out (one one of the healthy channels) approx 10.8VAC at 166 kHz. but on my dead channel; nothing!To be continued.JAH

author: tatfuture
author_rank: Contributor
timestamp: May 14, 2021, 07:20:05 am
content: keep going my friend

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: May 14, 2021, 01:28:36 pm
content: Consider designing an extension card to get the boards out for measuring. Surely worth a couple minutes of work with KiCAD and a few bucks at JLC.

author: tatfuture
author_rank: Contributor
timestamp: May 21, 2021, 06:53:25 am
content: please help meCURRENT OVERANGE
Repair backlight on oddball-sized 1602 LCD - Page 1
Forum section: electronics / repair

author: puterboy
author_rank: Regular Contributor
timestamp: June 12, 2025, 05:44:13 am
content: Several of the 1602 LCD displays on my DMP 7070 alarm keypads have broken/burnt-out LCD backlights.I would just replace the LCD but it is an oddball size (viewing size ~80x20mm, board size ~95x35mm) with no matches on Digikey, Mouser or Aliexpress.Otherwise board seems to have standard pinouts and orientation.Is it possible to replace the LEDs driving the backlight?Any instructions or links on how to do that without borking the otherwise working display and kepyad?

author: coromonadalix
author_rank: Super Contributor
timestamp: June 12, 2025, 08:51:09 am
content: photos, are they ac voltage driven or dc driven, not supposed to burn like that, or where over driven ...for dc voltage, it is normally a small thin rigid panel who can be slided under the lcd glass, you can un-solder it and change it, but the problem is the dimensionsfor ac it should be the same ... but once again dimensions, but some can be cut and adjusted to your needed sizein some case for the dc one, once removed some have accessible leds that can be changed ... if so, you need to adjust their intensity with resistors

author: benj38
author_rank: Frequent Contributor
timestamp: June 12, 2025, 08:42:34 pm
content: Usually small 1602 LCDs use a single 3mm LED, mounted on the side of the module (namely, into a plate of transparent acrylic below the LCD itself), as a backlight. These do sometimes die and need replacing.If you are lucky, the LED is not glued to the module, and replacing it is a breeze. Otherwise, you will need to drill it out (like you do a broken screw) since the glue is usually too strong to release without potentially damaging the LCD. Drilling is very easy, so you should not be afraid to do it. Just go slowly and carefully.
Repair Broken IC Pin - Page 1
Forum section: electronics / repair

author: bostonman
author_rank: Super Contributor
timestamp: December 17, 2019, 06:01:44 pm
content: I don't know how this happened, but I used a hot air pencil to remove a thru-hole IC and somehow a pin broke off at the base of the IC package. Since then, I am almost sure the IC wasn't bad and need to reuse it.A little metal is still visible. I'm thinking of inserting it into a socket and solder a piece of wire from the socket to the exposed metal.Has anyone attempted to grind part of the package to expose more metal?

author: magic
author_rank: Super Contributor
timestamp: December 17, 2019, 07:47:11 pm
content: Look up "DIP leadframe" to see what's inside. There is certainly a possibility of doing that, but be careful not to damage other pins while grinding. That stuff is pretty hard, somewhat brittle but not very easy to break and also resistant to any reasonable solvent you could try to etch it with.Don't grind too close to the central "island" which holds the die or you may tear bonding wires which connect the pins to pads on the die. Then you are genuinely SOL.

author: andy3055
author_rank: Super Contributor
timestamp: December 18, 2019, 07:23:28 pm
content: Yes, it can be done. The key is to expose enough metal for the solder to adhere to. Use an Exacto knife to cut off a little of the casing on either side of the broken pin (I have done it in the past in desperation at a time and place when things were not available!) rather than grinding as you can grind off accidentally what you already have exposed.Is this a custom IC or something that is obsolete that you can't find? What is the number on the IC?Can you post a picture?

author: dnwheeler
author_rank: Regular Contributor
timestamp: December 19, 2019, 07:21:17 pm
content: I would put the chip in a socket (permanently), remove a bit of the package around the broken-off pin (carefully scrape/pick with a pointed tool), then insert a discarded component lead into the socket hole below the missing pin, trim the lead to length and solder it to the exposed portion of the broken pin.
Repair broken ZIF socket for 20624 ribbon cable - Page 1
Forum section: electronics / repair

author: GreyArea
author_rank: Contributor
timestamp: March 10, 2021, 03:06:06 pm
content: So, er, yeah. OopsWhile "fixing" my dads laptop I seem to have broken the ZIF connector for what appears to be a 20624 ribbon cable. I'm a little , unwilling to dismantle it further if I can avoid it.I have a solder hot air gun, and if I can identify the socket I'd consider replacing it. I also thought about trying to solder the thing in there or glueing it, but thought I'd ask for help identifying the part and to get some advice.Thanks,

author: samnmax
author_rank: Regular Contributor
timestamp: March 10, 2021, 03:20:35 pm
content: I would just jam it in there and tape it over...Perhaps with a thin layer of material added to press the ribbon against the pins. It's just 4 low power pins for the power button and LED, right?

author: coromonadalix
author_rank: Super Contributor
timestamp: March 10, 2021, 03:23:43 pm
content: use hot air station to remove the connector and put a new one with the needed flat cable ptich, you have to check if the contacts are the bottom or top onesseems to be the bottom modelPatching and fiddling with it may end in bad contacts or problems

author: GreyArea
author_rank: Contributor
timestamp: March 10, 2021, 03:49:38 pm
content: Quote from: coromonadalix on March 10, 2021, 03:23:43 pmI don't suppose you any clues as to model number of the socket do you? So far I have it as a 1mm pitch 4P FPC connector of some kind. I've ordered a candidate off fleabay, but some certainty would be nice.And yes, agree that the other solutiont are a bit "How you doing?", replacing the socket seems best.

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 11, 2021, 07:45:12 am
content: you can remove isolation of your flat ribbon, remove connector and solder the ribbon on the pcb directly, you have the other side of the ribbon with connector for ddisconnecting the pcb's.