hybridfree/eevblog-posts huggingface dataset:
How to fix Vinegar Syndrome on NEC Supertwist LCD from 1986 - Page 1
Forum section: electronics / repair

author: MGaddict
author_rank: Contributor
timestamp: November 17, 2020, 03:17:36 pm
content: I have a perfectly working almost fully restored original NEC Multispeed laptop that was handed down to me back in 1991 and I continued to use for several years. The only problem is that the rear reflection/polarizing film has grossly deteriorated. I don't mind attempting to replace it as there is no way to replace the whole LCD however, I have never bought this stuff before and would love some recommendations on a reputable source for this type of film.Below are pictures of the front and backside of the panel separated from the board.

author: MGaddict
author_rank: Contributor
timestamp: November 17, 2020, 03:18:38 pm
content: Only 1 picture apparently posted. So here is the second.

author: shakalnokturn
author_rank: Super Contributor
timestamp: November 17, 2020, 08:33:56 pm
content: There are a few discussions on replacing polarizers on here, mostly related to Tektronix TDS 210/220 or Fluke Scopemeters.As for a reputable source for the adequate model... I'd be pleased know of one too.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 19, 2020, 05:01:33 pm
content: Finding such parts new will probably be difficult.Have you thought about taking apart some 2nd hand monitor?With a bit of luck you can probably find some second hand 14" monitors for a small amount of money.

author: MGaddict
author_rank: Contributor
timestamp: November 19, 2020, 07:51:42 pm
content: This appears to be a common issue to fix. It really is just a film that needs to be scrapped off and replaced. Apparently, old polarizer film, and some new stuff, just degrades and basically turns to vinegar (ergo Vinegar Syndrome). Since this is a vintage computer, one I owned as a kid, I'd really prefer to keep it as original as possible. I have no doubt I could find another screen, figure out the pinout for the connector and somehow build a custom controller to convert the signal to the new screen. But that is a ton of work for a simple problem.Lastly, we tend to be so wasteful with electronics today. I get it, if the polarizer film was $120, well, I can replace the whole laptop for that cost. But it's only about $10. So in this case, it really makes no sense not to fix it. I just don't want to spend $100 on different films until I find the right one. LOTS of people have done this, I just wish I knew what exact product they used from what company.Lastly, it's a 10"x5.5" 640x200 Green Yellow STN LCD. Only about a handfull of devices ever used STN for more than a calculator type screen. If you've ever used a calculator that doesn't have a backlight and has a green background with black text, that's exactly the type of display this is, just much larger. That's part of what makes finding the polarizer so difficult, it's sold in really tiny sizes for things like original Game Boys. Although even that used TFT LCD. But I know it's out there.Thank you though for your reply.
How to get rubber holster for bm827s or Greenlee dm-820a? - Page 1
Forum section: electronics / repair

author: Diesel11
author_rank: Newbie
timestamp: April 26, 2019, 03:50:48 am
content: I need a holster for my Greenlee dm820a red or green makes no difference to me. Thanks

author: DaJMasta
author_rank: Super Contributor
timestamp: April 26, 2019, 04:29:02 am
content: Have you tried contacting the manufacturer? It's a low enough pricepoint that they may not, but for a lot of more expensive current equipment you can often get feet or rubber surrounds as replacements. Otherwise your best bet is probably finding a broken unit to salvage it from or designing/3d printing a replacement for yourself, which is a pretty substantial task.

author: Diesel11
author_rank: Newbie
timestamp: April 26, 2019, 04:48:48 am
content: Thank u I did try the manufacturer maybe they will get back to me soon. I might lookinto a 3day printed version i suppose.Thanks for the help.

author: TheNewLab
author_rank: Frequent Contributor
timestamp: April 26, 2019, 05:19:36 am
content: you might also try Frankie at 99cents.com He got ahold of Brymen boot for my EEV Blog DMM
How to ´hack´ Supermicro PWS-721P-1R power supply - Page 1
Forum section: electronics / repair

author: ingalopez
author_rank: Contributor
timestamp: April 25, 2023, 01:41:43 am
content: Hey there!I ´ve received a server power supply PWS-721P-1R, to be checked. I can´t find info about how to turn the thing on. It seems to work, stby voltage appears, fan turns, just waiting a signal to turn on.I´ve found in The Breakout board Compatibility list, a breakout that (may?) work on this model, but no real recipe on how this is signaled on.Any help?Thanks!

author: mkiijam
author_rank: Regular Contributor
timestamp: April 25, 2023, 12:07:43 pm
content: Check with the technical support team regarding this.Email: support@supermicro.comTel: +1-408-503-8000 option 2

author: asis
author_rank: Frequent Contributor
timestamp: April 25, 2023, 04:43:50 pm
content: https://www.eevblog.com/forum/projects/supermicro-psu-pinout/Two Pon pins -> on gnd....or look at Russian-language sites...
How to improve shape of step generator - Page 1
Forum section: electronics / repair

author: watchmaker
author_rank: Unknown
timestamp: January 29, 2025, 03:02:20 pm
content: I am rebuilding a BK 501A curve tracer for fun. I found a couple caps below value (one EC in the pF range) and an overheated resistor.I included screenshots of the traces of interest as well as the schematic (I would suggest downloading it for future reference, is the centerfold of the oft missing parts list).The issue is the horrible slopes of the square wave. Sig self calibrated, probe is calibrated but I am using it at 1x.The first opamp (IC5) a 741 has steps but nasty slopes at the top. Tracing this back to IC3 and IC4, both outputs show horrible square waves. These are 7473s.C19 is the only one in common; it was low (around 400uF rather than 475) so I changed it. No change in the square waves. Swapped out IC 3 IC 4. No change. Verified functioning of old and new on the Retro IC checker I built.D11A to D12A (only D11 and D12 are populated) determine the number of steps. I verified they are ok.IC2 is delivering the correct signals. Out of superstition, I verified and swapped IC2 (a 7402)As you would expect, the signal at the base of Q8 and the collectors of Q8-Q10 are distorted.So it looks like IC2.Can I do anything to improve the steps? Or, is this just the way it is.Oh, all supply voltages are correct.THANKS!!!

author: mawyatt
author_rank: Super Contributor
timestamp: January 29, 2025, 03:50:27 pm
content: Try using DC Coupling on your scope, the AC Coupling might be the cause for the sloping. Use the Offset Function on the scope to center the traces up.Best,

author: watchmaker
author_rank: Unknown
timestamp: January 29, 2025, 04:01:55 pm
content: Quote from: mawyatt on January 29, 2025, 03:50:27 pmTHANK YOU. Measurement error. I am still uncertain when to use AC vs DC coupling. Should have just tried it though.Thanks again.

author: TimFox
author_rank: Super Contributor
timestamp: January 29, 2025, 04:30:13 pm
content: Simple rule: a slope on the square wave results from loss of low frequency response in a filter or amplifier (including the AC coupling on a scope input). A slow rise time results from a loss of high frequency response (including the finite bandwidth of the scope).
How to lower the maximum current output of usb charger? - Page 1
Forum section: electronics / repair

author: Fadsa36
author_rank: Newbie
timestamp: June 19, 2019, 04:07:37 pm
content: Good day to you, experts!This USB charge gives a maximum output of 0.8 A. I want to lower its maximum current to 0.3 A (short circuit current) without using resistors or regulators on the USB output. Tell me what to change?On the photo: a diode is hidden under the transformer, and a choke is between two capacitorsP.S. The question why: because the spots on the Sun. the question of security: burn the barn, burn the house. the question what I will connect: a nuclear reactor. the question of meaning: the meaning of meaninglessness

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 20, 2019, 01:34:09 pm
content: Unless you can find the datasheet for IC1, it's going to be very difficult. The easiest way would be to have a 2 transistor current limiter circuit added to the output, but you've stated you don't want to regulate the output. If the IC1 has a current limiting option on it, then it may be possible to mod the input side to limit the current further, but looking at it, I doubt it. It's a VERY cheap PSU, and not a very safely designed one from what I can see.

author: Ian.M
author_rank: Super Contributor
timestamp: June 20, 2019, 02:34:19 pm
content: I agree with LateLesley that it looks like a fairly crappy SMPSU, but at least there appears to be reasonable creepage and clearance distances between primary and secondary sides. However its behaviour when overloaded may well be unsafe so relying on its current limiting and modding that to a lower limit is probably unwise.With the above disclaimer out of the way, try replacing SMD resistor R7 (1.74 ohms) with a 4.7 ohm one. Either it will lower the limit or if you are unlucky it may let the magic smoke out!Caution: This part of the circuit is mains live.Reasoning: It appears to be between the MOSFETdrainsourceand the negative of the primary side DC bus, and has a track going to a dedicated pin on the controller chip IC1, so is almost certainly a current sense resistor to limit the peak current in the switching transformer primary. There doesn't appear to be any method of directly sensing the load current, so its existing current limit behaviour is probably determined by the input power.Edit: Corrected suspected MOSFET pin. The center one which is probably the drain goes to the transformer. b The other end one, most likely the gate, goes directly and only to IC1.

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 20, 2019, 10:34:50 pm
content: I really like the way they have drawn what look like PCB spark gaps between "Live" and GND/5V... on what I'm guessing is an un-earthed device.
How to NOT repair a Fluke VP210 probe (pics teardown, disassembly) - Page 1
Forum section: electronics / repair

author: Zucca
author_rank: Unknown
timestamp: August 16, 2025, 12:06:54 am
content: Yesterday I got my hands on a defectFluke VP210red probe: no connection between probe tip and center BNC.I found nothing online so I decided to attempt a repair.I destroyed the probe but I (probably) found the problem. This post is to document my bad adventure so in the future I could help somebody with a similar problem.Let's start by taking apart the BNC assembly:pry gently the top part, take your time and it will separate. See the two blue arrows to understand what is holding everything in place, you could help the process by pushing down the plastic in the hole(s) (180deg symmetric on the other side)...The problem after that was quite obvious:the tiny and thin core wire (center of the probe coax cable) was disconnected from the PCB.It could have been a doable repair if I did not took a part the probe tip first:basically destroying the probe.

author: neverendingstudent
author_rank: Regular Contributor
timestamp: August 16, 2025, 12:48:49 am
content: This is useful! I had tried to see if I could disassemble it and got as far as pushing that black nub in which let me rotate it to expose the calibration trimmer, but it didn't feel like I could do anything further with non-destructive methods and I absolutely *could not find* anything online for how to disassemble the probe.Given the probe was spoken for I didn't feel like I could risk anything further that might be destructive so I left it alone.My theory was that it would have been a break in the center coax somewhere in the cable itself, since I remember reading somewhere that that is the most common mode of failure for scope probes - user mishandling by ignoring bend radius and 'tying up' a probe cable like you would an extension cord for storage.
How to open a Dell KJ321 battery pack. - Page 1
Forum section: electronics / repair

author: Hank
author_rank: Newbie
timestamp: May 31, 2022, 07:21:05 pm
content: As it says on the tin, I'm absolutely clueless about how to open it, so maybe someone has some bright ideas, or might even have opened one him/herself.

author: strawberry
author_rank: Super Contributor
timestamp: May 31, 2022, 08:02:20 pm
content: not made to be opened. break it apart in the way it will be possible to assemble/glue it back together (when repair is planned)harder to find exact replacement size when it is not 18650 cell

author: tunk
author_rank: Super Contributor
timestamp: May 31, 2022, 08:46:39 pm
content: I've taken apart a handful of laptop batteries to salvage the cells.Usually I start around the battery contact with a screwdriver, takingcare not to short anything, damaging the cells or yourself.There's some videos on youtube, you could try these keywords:salvage 18650 from laptop

author: mikerj
author_rank: Super Contributor
timestamp: May 31, 2022, 10:45:41 pm
content: The cases are typically clipped AND glued or ultrasonicaly welded together, considerable force is often needed and damage to the casing is likely. OTOH I have had a few packs that came apart relatively easily with a spudger, but they are the exception.
How to open a Vision Mantis? - Page 1
Forum section: electronics / repair

author: VK3DRB
author_rank: Super Contributor
timestamp: June 08, 2020, 01:12:07 pm
content: Hi.I have a classic Vision Mantis. I want to disable the fan because it is noisy and not needed as I replaced the quartz halogen lamps with LED lamps. I read somewhere that if the machine is opened, the optics can go out of alignment and then the machine has to be sent to the UK for alignment.Has anyone opened up a Vision Mantis without issues? If so, how do you open it? I could find no manual on the web.

author: giovannirat
author_rank: Regular Contributor
timestamp: June 08, 2020, 05:54:39 pm
content: You can open a Vision Mantis without issues.In my case a mirror inside was loose, I could repair it easily.Service Manual in the attachment...
How to open flex cable connector  - Page 1
Forum section: electronics / repair

author: lartsu
author_rank: Contributor
timestamp: April 15, 2024, 04:23:38 pm
content: Could you help me a bit..I'm not sure how to open this type flax cable connector (Nikon Z7 lcd cable). How to open this type of connector?Thanks in advance.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 15, 2024, 04:34:32 pm
content: There's usually a lever on the side that lifts up and releases the FFC. On this connecter, it looks like the white piece may be that part.

author: lartsu
author_rank: Contributor
timestamp: April 15, 2024, 06:06:16 pm
content: It seems that there is no lever to lifting it up. I want be sure how to open this type of connecter.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 15, 2024, 07:17:05 pm
content: Here's a grossly similar one from Molex. It is open, and apparently the black part just tilts up. In all cases I have seen, a part over the cable swings up. When you re-insert the cable, it snaps back down to hold the cable. Do that carefully to be sure everything is aligned. Some have a latch on the side, others, just a fingernail under the movable part opens it. The Nikon D70s I disassembled was the latter type. The latch was brown rather than black. It doesn't take much force.Be sure us wear ESD protection.

author: lartsu
author_rank: Contributor
timestamp: April 15, 2024, 08:02:55 pm
content: It's not same style as in your picture which opens on cable side. There are also these connecters but this connector in question is different. Most likely it opens on other side but I want to be sure.

author: amyk
author_rank: Super Contributor
timestamp: April 16, 2024, 03:39:03 am
content: It's a Hirose "back flip" connector:https://www.hirose.com/en/product/series?category=FPC-FFC_Back-FlipMight be TF29:https://www.hirose.com/en/product/series/TF29
How to Program a Dallas DS1245W? This is a 3.3V Device. - Page 1
Forum section: electronics / repair

author: calibrationfixture
author_rank: Regular Contributor
timestamp: January 18, 2025, 02:06:10 pm
content: Hi to All,Contrary to the 5V Versions, my Batronix Programmer doesn't cover these 3.3V Versions. I could lower the Vcc with two Diodes in series and make the Vcc connection out of the ZIF-Socket. A legitimate solution? Thanks in advance for any insights.Calibrationfixture

author: Ian.M
author_rank: Super Contributor
timestamp: January 18, 2025, 03:00:24 pm
content: No. The datasheet says:Quotewhich means the address, data and control pins are *NOT* 5V tolerant. If the programmer is using 5V Vcc with CMOS thresholds, it will overdrive the Dallas DS1245W pins.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 18, 2025, 06:06:43 pm
content: @calibrationthere was no need to restart a thread about your equipment, your diluting the subject into many parts, many are doing this nowadays and it get really annoying to followjust find a programmer for itTL866A or CS, TL866II, Xeltec and others can do it, arduinos projects can do some of them etc ...

author: DonKu
author_rank: Regular Contributor
timestamp: January 18, 2025, 06:31:22 pm
content: Quote from: Ian.M on January 18, 2025, 03:00:24 pmIf you have the time, it's fairly easy to construct a DIY bi-directional voltage level shifter:

author: Ian.M
author_rank: Super Contributor
timestamp: January 18, 2025, 07:44:54 pm
content: True, but will a simple discrete MOSFET level shifter be fast enough for a programmer running a RAM chip definition, that wont have any extra delays?Its probably easier to breadboard a dedicated 'burner' using any 3.3V Arduino with enough I/Os.
how to program ATMEGA48PA-AU?? - Page 1
Forum section: electronics / repair

author: stormrazer121
author_rank: Newbie
timestamp: September 28, 2023, 05:48:07 pm
content: So long story short ive a bait boat that has a faulty IC, ive been able to narrow it down to this however in my great wisdom of replacing the faulty ATMEGA48PA-AU i failed to realise something..i cannot program itHow would one go forward to learn how to do this??

author: Audiorepair
author_rank: Frequent Contributor
timestamp: September 28, 2023, 08:17:16 pm
content: You get something like this.https://xgecu.myshopify.com/collections/xgecu-t48-tl866ii-3g-programmerAnd the adaptor that fits the AT device you want to program.The software is free, and there really is little or no learning curve involved. its all just built in.I have the older version of this, it just connects to a laptop/PC with a USB cable.It has the added advantage of having a built in CMOS (40xxx) and TTL (74xxx) series logic tester.

author: wraper
author_rank: Unknown
timestamp: September 28, 2023, 08:42:40 pm
content: But do you have a firmware to program to begin with?

author: Audiorepair
author_rank: Frequent Contributor
timestamp: September 28, 2023, 09:11:20 pm
content: Ah, I forgot about that bit.

author: stormrazer121
author_rank: Newbie
timestamp: October 04, 2023, 10:33:47 pm
content: Thats the main issue i guess is that i do not have any firmware for itlittle lost on this one!

author: amyk
author_rank: Super Contributor
timestamp: October 05, 2023, 02:33:43 am
content: Either you read it from the old one (unlikely to succeed if it's damaged or code-protected, although there are companies in the East who can break the latter for a few k$) or write it yourself.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: October 07, 2023, 09:25:26 am
content: you can use something like this to do the programming:https://www.ebay.com/itm/404348353863("USBASP USBISP AVR Programmer Adapter")that costs just a few dollars on ebay.then use an open-source program called avrdude:https://github.com/avrdudes/avrdudehowever, as others have pointed out, getting hold of the binary data to program into the device going to be the problem.cheers,rob :-)

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 07, 2023, 09:29:30 am
content: NeoProgrammer can do it using an inexpensive CH341A.NeoProgrammer 2.2.10-Original link-Mirror
How to program the winbond NAND W29N01GVSIAA - Page 1
Forum section: electronics / repair

author: 800908
author_rank: Contributor
timestamp: November 09, 2020, 06:38:47 am
content: HiI have winbond NAND chip that I want to read and write on it.there is UART test points on the device that I can connect it to black CH341a programmer but I don't know how.the part number is W29N01GVSIAA.thanks.

author: ataradov
author_rank: Super Contributor
timestamp: November 09, 2020, 07:41:03 am
content: Programming it in circuit - depends on the device. Having UART may not be enough.Outside of the circuit - using any programmer that supports NAND devices.

author: 800908
author_rank: Contributor
timestamp: November 09, 2020, 07:56:59 am
content: thanks Alex.the device also has E-JTAG test points.is this help reading and writing?I searched the internet for NAND programmer but all I found was for Apple iPhone.do you know any cheap one that can do the job?

author: ataradov
author_rank: Super Contributor
timestamp: November 09, 2020, 08:01:46 am
content: Quote from: 800908 on November 09, 2020, 07:56:59 amI'm not sure what "E-JTAG" is. If you have an actual JTAG port, then it still depends on the device that this port goes to. Generally you can use boundary scan to access the NAND flash pins and bit bang the read/write sequence. It will be slow (very slow), but this is the most universal method. There are probably some standard tools for that, but I do't know any.Quote from: 800908 on November 09, 2020, 07:56:59 amNo idea, I've never used them. I know they exist, since USB flash drive recovery people use them. Not sure of price ranges.

author: fzabkar
author_rank: Super Contributor
timestamp: November 09, 2020, 08:27:23 am
content: I suggest you search the hddguru.com forum. I think there was a discussion in recent months on this subject.

author: 800908
author_rank: Contributor
timestamp: November 09, 2020, 08:32:57 am
content: thanks. I will.

author: asis
author_rank: Frequent Contributor
timestamp: November 10, 2020, 02:34:21 am
content: Hi,Have a look athttps://www.embeddedcomputers.net/products/https://www.embeddedcomputers.net/products/FlashcatUSB_Mach1/I bought from here:https://www.ebay.com/str/darkwireOrder Mach1 PCB v2.xhttps://www.blackcatusb.net/index.php?threads/eof-announcement-flaschatusb-professional-4-0-and-xport-pcb-1-x.672/
How to recover data from FLASH ROMs - Page 1
Forum section: electronics / repair

author: testtube44
author_rank: Regular Contributor
timestamp: October 23, 2019, 08:35:42 am
content: How difficult is it to recover data from these flash ROM chips?http://www.cypress.com/file/177976/downloadS29GL01GS10TFI020 and S29GL128S90TFI020

author: Simon
author_rank: Unknown
timestamp: October 23, 2019, 10:54:49 am
content: Please do not double post the same topic. it annoys people.
How to remove the central pin from a BNC crimp connector - Page 1
Forum section: electronics / repair

author: iMo
author_rank: Super Contributor
timestamp: January 02, 2025, 12:18:49 pm
content: I got a bunch of BNC crimp connectors (for RG58, male) in past with the central pin inserted (vanilla, not crimped). While making couple of cables I wanted to use them as well, but it seems to me it is not so easy. The central pin is somehow locked inside the white teflon insulation and cannot be pushed out from the front side (I do not want to damage them so I tried with a small force so far).Is there a trick or a tool how to free up the central pin?

author: inse
author_rank: Super Contributor
timestamp: January 02, 2025, 12:45:04 pm
content: At some connectors, the pin locks in the insulator.If you push it out by force, the core plus dielectric will probably have to support the pin on reuse.Should not be a problem with RG58 cable

author: iMo
author_rank: Super Contributor
timestamp: January 02, 2025, 01:01:53 pm
content: Yup, that is the case.. I've tried too and it "clicks" when the pin is pushed in.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 02, 2025, 05:34:31 pm
content: sometime you can push them backward, but you would need to sacrifice one, to see if it is reusable or it destroy the "snapping effect" if you rebuild the connector ...

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2025, 05:54:11 pm
content: Do you have the model number of the connector so you can find the original assembly instructions? In most coaxial connectors, the center pin attaches directly to the conductor. But there are some where the pin is permanently installed in the connector, and you crimp/solder an inner pin to the conductor, which then fits into the actual pin.Also, Teflon softens a lot with heat. You may be able to extract the pin more easily if you first heat the connectors in an oven, at perhaps 100-130 degrees.

author: iMo
author_rank: Super Contributor
timestamp: January 03, 2025, 06:51:47 pm
content: A friend of mine has made a tool for removing the pins, and we've tried.. A thin tube with an internal movable solid steel wire pushing the pin down.With a certain force (pretty large, frankly) the pin jumped off when pushed down, with a "click". Out of my curiosity I pushed it back into the connector to see whether its removal has deformed the teflon - and it clicked nicely when I pushed it in and also when I removed it back afterwards.No idea what is the part number or the type of the connector, I got a bag of them decades back on a local flea market almost free, the half of the connectors with pins inserted in (somebody played with them and they stuck).So be careful when inserting the pins into the BNC connectors, it might be pretty difficult to get them back.
How to repair broken pad that leads to other side of the board? - Page 1
Forum section: electronics / repair

author: ThingWizard
author_rank: Contributor
timestamp: April 25, 2021, 10:16:07 am
content: Hi!I'm repairing a usb socket for my old phone, the 5V pad is ripped and there is a tiny copper trace underneath it, leading to the other side of the board (confirmed with schematics)Now, what would be the best way to repair this? Should I just drill out the "through-trace" and put a jumper wire through to the other side or is there a smarter way?So it's something like this: (Excuse the crudity of the model, I didn't have time to build it to scale or paint it)EDIT:Hmm, I might have been a bit trigger happy there on the forum fishing, it seems the pad extends to the side of the 5V pin, and it is full of small throughholes to the pad on the other side. It is not just the one under the leg. (Makes sense). So I think I'll be fine just grafting on something to that pad.However- I'm still interested in knowing how you would fix a broken pad "on the other side" as there is no trace on the pad side.
How to replace glass in SAN WEST analog meter? - Page 1
Forum section: electronics / repair

author: theHWcave
author_rank: Regular Contributor
timestamp: February 11, 2024, 01:01:53 pm
content: Hi, I am repairing a Wayne Kerr B642 bridge and the only job left is to re-attach the pushed in glass on one of its SAN WEST instruments. Problem is that I can't see how to remove the bezel / housing. By brute force I managed to create a gap on the top to get the glass out and then repair the bashed needle so the meter works (amazingly) but that method is unsuitable to get the glass back in and glue it.I thought the cover may be just clipped-on but in trying to remove it I just started to break the plastic. I must be missing a trick.Anybody out there who knows how to properly open these to replace the glass?

author: Jwillis
author_rank: Super Contributor
timestamp: February 12, 2024, 02:27:07 am
content: No trick. They're just not designed to be serviceable.

author: theHWcave
author_rank: Regular Contributor
timestamp: March 12, 2024, 09:42:18 am
content: To answer my own question. The glass and scale of these meters are entirely repairable. The trick is to take the plunge and remove the plastic caps, which after many attempts, I could only manage destructively. That reveals a nut that requires (ideally) one of those 2-prong bits. With the nuts removed the meter comes apart allowing access to glass and scale if needed. On reassembly, there is an O-ring that is a bit tricky to align at the rear, but overall no problem.For those who are interested, this sequence of pics is from a (much) bigger repair video on the Wayne Kerr B642 Autobalance Universal Bridge.part 1:https://youtu.be/i9G0Pjc-pnopart 2:https://youtu.be/gPMkD3Lyb0wThe repair of the analog meter is in part 2 at about 18:34

author: donlisms
author_rank: Frequent Contributor
timestamp: March 13, 2024, 01:16:24 am
content: I enjoyed that very much! Thanks for sharing. The box looks great - and big! The kind of thing I would like to have if I could. Good job repairing it!(I thought Wayne Kerr was a singer in a night club or something. :-) )
How to replace resistive humidity sensor on weather station - Page 1
Forum section: electronics / repair

author: duzycinek
author_rank: Contributor
timestamp: November 05, 2022, 04:01:50 pm
content: Hello, I got problem how to decide which humidity sensor should I buy for replacement in my weather station transmitter. I got N25FR wireless 433mhz weather station model WH1050 and it has resistive humidity sensor inside, which is faulty. It measures about 12-15% air humidity all the time. I was searching for replacement but noticed that almost every sensor is powered by VAC. After few measurments it seems my sensor is powered by 3VDC(2 AA series battery). Anyone have experience with stations like this and could advice which sensor replacement should I buy? Adding photos of sensor with module and measurments with osciloscope on both legs of sensor.

author: TheMG
author_rank: Frequent Contributor
timestamp: November 05, 2022, 10:46:51 pm
content: Looks like a bog standard HR31/HR202 type sensor or similar.By the way, it's capacitive not resistive.

author: duzycinek
author_rank: Contributor
timestamp: November 06, 2022, 08:28:56 am
content: Yes, I noticed it also, but the problem is that these sensors should be powered with AC. It is not problem on this case? They also works with DC?Quote from: TheMG on November 05, 2022, 10:46:51 pmYes, sorry, my bad.

author: duzycinek
author_rank: Contributor
timestamp: December 12, 2022, 12:58:52 pm
content: Hello, if anyone was interested, it seems that is HR31 sensor. Readings are almost same as orginal one.

author: testpoint1
author_rank: Frequent Contributor
timestamp: December 15, 2022, 05:26:52 am
content: it is HR202L, 100% is resistance sensor, capacitor is different, I have much more in hand, if you in US, free one for you.

author: duzycinek
author_rank: Contributor
timestamp: December 15, 2022, 10:46:49 pm
content: Thank you, sadly I am from europe
How to safely short 2 legs of an NPN? - Page 1
Forum section: electronics / repair

author: brokenbones
author_rank: Newbie
timestamp: October 02, 2025, 01:33:35 am
content: I'm troubleshooting a 20V DC bench power supply. I'm getting high output...Test procedure tells me to short Emitter to Base of an SI NPN while in circuit, with the device on.What is a safe way to create this short?

author: cruff
author_rank: Regular Contributor
timestamp: October 02, 2025, 01:41:41 am
content: Tack two wires to the E and B terminals to a push button switch? Are they adjacent to each other and can you reach them safely? Maybe bridging them with a screwdriver would work if you don't slip.

author: brokenbones
author_rank: Newbie
timestamp: October 02, 2025, 01:49:55 am
content: My first thought was to short the board with an insulated screwdriver. I do have easy access to both sides of the PCB and the solder joints are fairly clear from any other points.

author: marhuum
author_rank: Contributor
timestamp: October 02, 2025, 08:46:55 am
content: alligator clip,being modified spring strength, so long reach but not harmingly give pressure

author: rvalente
author_rank: Frequent Contributor
timestamp: October 02, 2025, 11:56:06 pm
content: Old tweezers?
How to Test an Electric Motor - Page 1
Forum section: electronics / repair

author: electronbean
author_rank: Contributor
timestamp: December 30, 2023, 04:51:20 am
content: I am struggling with this electric motor.This motor is composed of these parts:Rotor:https://ibb.co/FDXB80vStator:https://ibb.co/FWqnt60Is managed by a speed regulator (PWM). I want to test this motor by applying 230VAC to its terminals to see if the motor works well. I know, but I don't have an oscilloscope to debug PWMMy question and doubt are: If I put 230VAC directly into the leads of this motor, should it work, right?This is the two wire I have to connect the motor:https://ibb.co/nLpZ4mT

author: Ian.M
author_rank: Super Contributor
timestamp: December 30, 2023, 05:37:03 am
content: It appears to be a universal motor so would be capable of running on AC. However for speed controlled motors it isn't uncommon for manufacturers to use a 100V motor world-wide and use a region dependent speed control module that limits the max. average motor voltage to 100V, so bypassing the speed controller in a 220V-240V country may be risky.Try running it with no load on its shaft, on 12V DC. It should spin steadily at a smallish fraction of its normal speed. If its jerky there's probably something wrong with it.Also try a low wattage mains incandescent bulb in place of the motor. (not greater than 10% of the motor watts). The speed control should vary its brightness.
How to test double conversion UPS with dead batteries - Page 1
Forum section: electronics / repair

author: V_King
author_rank: Regular Contributor
timestamp: October 16, 2023, 02:22:30 pm
content: Hello,Is there a way to test a double conversion UPS with dead batteries?There was a 10KVA double conversion UPS being thrown away by our neighbours. They said it was working before they put it into storage. I though it would be great to try using it, because we have some conductive noise issues coming through mains, due to industrial machinery running in one of the units nearby.BUT the batteries are dead in the UPS and when I power it up nothing is happening. Checked all the fuses everything is ok. I can only assume the main control board is powered from batteries? The batteries are 12VDC standard sealed stuff, but 26pcs are needed to get 312VDC required.The unit is manufactured by Chloride Power Protection and there is very little info online.

author: m k
author_rank: Super Contributor
timestamp: October 23, 2023, 08:41:24 am
content: It's quite possible that battery voltage must be present before anything happens.It's also possible that somewhere is a setting for use without batteries.

author: SeanB
author_rank: Super Contributor
timestamp: October 23, 2023, 09:01:48 am
content: No they need the batteries, as they power a small DC DC converter that powers the input rectifier and output circuits. The batteries also act as a large capacitor as well for the output side, and the ripple applied to them does contribute to the batteries failing. If the 7Ah SLA packs are not totally flat, charge them up for a few hours, and see if they recover, and then they will run it briefly. But you do need to replace all of them though, and probably also a good number of the wire jumpers with spade connectors that join them in series as well, as they will have corroded from being stored discharged.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: October 23, 2023, 09:07:17 am
content: Makes sense the UPS runs off battery. I suggest the SLAs have long sulphated. An expensive and heavy fix. You can simulate the battery voltage on the PCB using a bench supply to see if the syscon powers on. But you will not be able the test under load. Are the batteries in series, parallel or a mix?

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 23, 2023, 10:24:03 am
content: Quote from: V_King on October 16, 2023, 02:22:30 pm312 VDC (possibly regulated?) isolated power supply may help instead of 26 batteries. But it is good if it has a current limit feature or any other current limiting part.

author: fmashockie
author_rank: Frequent Contributor
timestamp: October 23, 2023, 12:17:23 pm
content: Speaking from experience testing/repairing much smaller UPSs, I would much prefer to simulate the battery(ies) using a DC power supply. Without knowing the exact condition of the unit, hooking all those batteries up and powering it on could result in some dangerous amounts of current drawn if there's a short somewhere within the unit. A DC power supply with current limiting as VovK_Z said would be your best bet for testing
How to test Hakko 470b heating element - Page 1
Forum section: electronics / repair

author: PoDuck
author_rank: Regular Contributor
timestamp: October 09, 2023, 04:37:50 pm
content: I acquired a Hakko 470b desoldering station that won't heat up. I assume that it's got a bad heating element, but I'm not sure, so I tried to test for voltage. I get no voltage. My first assumption was that the base that is bad, but after thinking about it for a minute I thought that a failsafe design would rely on the temperature sensor to be operating before heating up the element, which would prevent the base from sending power if the thermocouple is bad. I don't know enough about the operation of these to know how to test that though.Am I correct about this type of failsafe, and if so, how do I test that I will get voltage to the heating element if I have a good thermocouple? In other words, what do I have to do to the thermocouple input to get the base to send voltage to the heating element output?Thanks

author: edavid
author_rank: Super Contributor
timestamp: October 09, 2023, 04:55:44 pm
content: Open the gun and measure the resistance of the heating element, as described in the manual.

author: blauerscharik
author_rank: Regular Contributor
timestamp: October 09, 2023, 05:21:39 pm
content: I had a similar fault once. Iron wouldn't heat up. I measured the resistance of the heating element and it was OL. So I thought hhhm what if I solder a light bulb to those terminals? So I did. The light bulb started glowing and the iron got hot too. I de-soldered the bulb and the iron started working again. Don't know what that was all about.

author: floobydust
author_rank: Super Contributor
timestamp: October 09, 2023, 06:27:47 pm
content: more here:https://www.eevblog.com/forum/repair/hakko-470-471-de-soldering-station-schematic/msg1296987/#msg1296987

author: PoDuck
author_rank: Regular Contributor
timestamp: October 09, 2023, 06:45:25 pm
content: Okay, tested the lead and got ol. Opened up the gun, and pulled the heating element out, and the wire came apart from the element. Answers the question.Thanks.

author: Miti
author_rank: Super Contributor
timestamp: October 09, 2023, 11:43:24 pm
content: Quote from: PoDuck on October 09, 2023, 06:45:25 pmThose heating elements are very expensive but don't throw the bad one. I fixed mine and it still works after more than a year. Take a paper clip or some strong steel wire and try to push it in the hole where the heating wire broke. You may touch the broken end. Then you'll have to be creative with how to keep it pushed in the hole while assembling it. Use heat resistant materials like silicone or mica and shove it around the paper clip wire.

author: PoDuck
author_rank: Regular Contributor
timestamp: October 13, 2023, 03:30:13 pm
content: There is no hole to put the wire into. It appears that the connection broke cleanly, and I would have to solder the wire back down with some sort of high temperature solder, which I don't have. I just went ahead and bought new parts for an 809.
How to troubleshoot power supplies emit high pitched tone in standby - Page 1
Forum section: electronics / repair

author: Odd
author_rank: Regular Contributor
timestamp: April 27, 2025, 10:46:38 am
content: I have seen this in computer PSU, USB-PSU and monitors. : When the device is in sleep, or uses very little power - then they start to emit a high-frequency beeping noise.This is a failure type that appears with time, so capacitors, or loose windings or something like that.Please post advice on how to locate/fix.

author: MathWizard
author_rank: Super Contributor
timestamp: April 27, 2025, 11:46:49 am
content: A low tech way that might help, is take a tube, like a paper towel roll, or rolled up sheet of paper, and see if you can narrow down where the noise is coming from.Most modern PSU's while use high frequency switching, much higher than we can hear, but some of that energy can make parts vibrate at frequencies we do hear.And also, when you say it beeps, are there silences in between ? Some PSU's and their controller IC's will run for a brief period, like charging up a battery, then sit back and wait for that little reserve of power to be used up, and turn on again.1 of my old computer PSU's has an annoying sound, but yeah I never bothered trying to narrow down where it came from.I've heard of cap and coil whine over the years, but yeah IDK if anyone has luck getting rid of or reducing it or not, just with glue or chalking type materials.

author: Odd
author_rank: Regular Contributor
timestamp: April 28, 2025, 04:41:30 pm
content: yep, thank you - I hoped that there were some tools that could help pinpointing the exact source of the noise.

author: MathWizard
author_rank: Super Contributor
timestamp: April 28, 2025, 06:10:49 pm
content: If you have some basic parts, like a few resistors, caps, 1-2BJT's, or an op-amp, and a basic microphone like in an MP3 player, and a speaker or anything like a stereo/MP3 player, could could make a little audio amp and probe around that way.
How to turn this Philips LCD TV PSU (FSP140-4FS01) on? - Page 1
Forum section: electronics / repair

author: Geronimo
author_rank: Contributor
timestamp: December 23, 2021, 02:15:20 pm
content: I have a broken Philips LCD TV (55PFL7008K/12) on my desk, basically the Main PCB (so called SSB) is broken due to the known issue with the bad cooling and overheating of the Fusion P120 CPU. This one was probably long dead before I got it. I tried to reflow the CPU, it failed, but this is another story.Now I would like to use a cheap chines LCD controller (an HDVX9-AS V4.2 in combination with an PL.MS6M30K.1 for those interested) instead of the original SSB and in basic I have it all ready for reassembling, I only need to know how to provide power from the original PSU. 12V is all the new controller needs. Of course, the original PSU has to continue driving the LED back/edge light with its proper voltage (I guess 96V). That’s anyhow where my actual problem starts...According to what I could find about it, the former SSB sends the “power on” signal to the PSU. This is, as far as I know, done by pulling down the STB (PS-ON) signal (on Pin 10 of the PSU connector) to GND. I have tried this in different ways with the PSU put down on my work bench. Neither by using a current limiting resistor or directly shorting the Pin 10 down to ground, the PSU likes to turn on an provide the other voltages (e.g. 12V on PINs 11,12,25,26).I guess the PSU (FSP140-4FS01) is also monitoring the LED Edge-light supply voltage. On the other hand, I expected to see at least a short time long some voltages to appear on the other PINs (i.e. PINs 11,12,25,26). The Stand-By voltage on PINs 9 (3V3s) and also on PIN 10 (STB) are always there (3.4V DC).What am I missing here?Is it possible to turn the PSU on w/o the other connectors populated (e.g. the LED driver circuit)?How does the STB power on signal thing work and what am I doing wrong?The PSU is for sure in working condition, I have cross checked this with another SSB in another TV.Can anyone help to get me out of this mess?Cheers, have a great Christmas and a very happy new year!Geronimo

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 24, 2021, 12:36:01 am
content: must have new PSU mimic (almost) exact original PSU ratings specs
How to uninstal/reinstal the battery driver on a MS Surface Pro 7 - Page 1
Forum section: electronics / repair

author: lexibeamin
author_rank: Contributor
timestamp: May 30, 2024, 03:45:06 pm
content: Hello beamin/lexi has risen again to much dismay.I bought a surface pro7 due to the last surface pro having charging issues. My philosophy was instead of a cheap walmart lap top for 300$ I'll get the nest one so it will last longer. Nope wont charge just like my other surface where that one was like 1999$ went through four under warranty.So im almost 100% its soft/firmware, because I bought a new charger because the last one died for only 89$ but real microsoft charger.Anyways iI see in settings an option to uninstall, but how do I reinstal like where does the file come from, CDROMs are long gone, how do I get the same or new driver back on?This computer is like my life so I dont want to break it.I had to explain to the Kid at geek squad BestBuy the difference in SSD HDD and RAM. He thought SSDs were RAM. HOW DID YOU GET HIRED? he definitely wasn't going to know how to help.If I go dark its because of a damn charger thats trying to ruin my life. Thanks Bill...

author: lexibeamin
author_rank: Contributor
timestamp: May 30, 2024, 04:14:09 pm
content: "Click the arrow icon next to Batteries. Right-click Microsoft ACPI-Compliant Control Method Battery. Click Uninstall device. Restart your Surface Pro, and Windows will automatically detect the missing driver and reinstall it"Found this:OK simple. Do I need the charger on and working to do this? I'm so nervous to screw it up because after posting and messing around with the charger it just started working. I updated something but had nothing to do with harddware I think?Also I cant believe this is glued shut. So no chance of pulling the SSD and fixing like I used to.We seriously need right to repair bills. Whats the most frustrating thing I have ever done?Gone to washington DC and tried to get laws passed WITHOUT a briefcase of cash. Not going to happen, but know how to do it. People have no idea how hard that is.I was watching that battery light like crack head thats spilled all his crack.

author: amyk
author_rank: Super Contributor
timestamp: May 31, 2024, 01:37:10 am
content: Quote from: lexibeamin on May 30, 2024, 04:14:09 pmAs the saying goes, "vote with your wallet". Plenty of other easily serviceable laptops still available, and yet you bought one of the least serviceable ones.

author: Haenk
author_rank: Super Contributor
timestamp: May 31, 2024, 05:21:06 am
content: You should check iFixit, they often have teardowns of new devices from all major manufacturers - and will judge in the possibility to repair it.I think France now hast laws in place that require manufacturers to state a repairability index.However I don't see modular notebooks ever returning.
How to unlock Level 2 calibration functions without 6-digit key? - Page 1
Forum section: electronics / repair

author: augustaulrich
author_rank: Newbie
timestamp: January 03, 2025, 09:27:38 am
content: Hello,I recently acquired a Marconi (IFR/Aeroflex) 2024 signal generator. Everything seems to be functioning well, except for the AM modulation depth, which only reaches about 92% at full modulation. How can I access the "Level 2" calibration functions without the 6-digit key?

author: George Edmonds
author_rank: Frequent Contributor
timestamp: January 03, 2025, 11:02:25 am
content: HiYou cannot do so.Send me your insruments serial number (rear panel) and it's ESN (display) and I will generate you an unlock code to level 2. This unlock code is for your instrument ONLY.G Edmonds