hybridfree/eevblog-posts huggingface dataset:
Need an Equivalent Ic  - Page 1
Forum section: electronics / repair

author: abdolah
author_rank: Regular Contributor
timestamp: February 21, 2024, 10:47:17 pm
content: So in my PSU I have WT7579 pwm supervisor icand I can't find it to buy it or find the equivalentThe ic is 20 pin . It has a pext pin for temperature sensorThe only pin out needs explain for the pins . Or an equivalent Ic

author: Jwillis
author_rank: Super Contributor
timestamp: February 22, 2024, 12:29:53 am
content: TheEST7502Bis characteristically equivalent but not pin equivalent.For either your probably going to have to search distributors with New old stock. Aliexpress or Ebay and hope you don't get shafted.

author: abdolah
author_rank: Regular Contributor
timestamp: February 22, 2024, 01:21:16 am
content: I did ask multiple traders on AliExpress but they don't have the wt7579 . I found the closest one is wt7522 it a dip-20 too but the pinout is deferent like you saidI just want to understand what is vs12c & Is12c & vs12d & is12d& Vs12B & is12B & is12A & vs12AAll of those pins , I think I need only 2 for the 12v but Wich one and what are the other pinsThe pins are 5 & 16 , 7 & 8 , 9 & 12 , 10 & 11

author: Jwillis
author_rank: Super Contributor
timestamp: February 22, 2024, 02:53:42 am
content: The difference is the number of channels. The WT7579 is 4 channel. The WT7502 is a single channel without 12V sense. The EST7502B is single channel with 12V sense and features like soft start.The EST7502C/EST7502CS are 3 channel with other features like soft start.VS12A,B,C,D are 12V over voltage & under voltage & over current sense input pin for each channel A,B,C,DIS12A,B,C,D are 12V over current protection sense input for each channel A,B,C,D

author: DavidAlfa
author_rank: Super Contributor
timestamp: February 22, 2024, 04:07:26 am
content: SG6521, same pinout with less channels, will probably work.Still, it's unlikely to be the culprit, those ICs rarely go bad.Also you damaged all the PCB pads, the upper/lower traces will no longer make connection, it's going to be a messy repair.What's the point of all this? You can get a new PSU for cheap.

author: abdolah
author_rank: Regular Contributor
timestamp: February 22, 2024, 05:47:34 am
content: Yes . Thanks you so much for the explanationI found ps223 is the choice because it has a OTP but it's only 2 channelThe question now can I buy 2 and connect 1 for 2 channel and the other for the other 2 channel?If yes . How is the connection going to be Parallel all the way ?And thank you for your help and time I really appreciate it

author: abdolah
author_rank: Regular Contributor
timestamp: February 22, 2024, 05:55:22 am
content: Ok thanks for the help . Thats a good equivalent to itPower supply are expensive in my country so repairing it is a good deal + it a good power supplyThis board is 2 layer I think so the vias are not a big deal, unless the it's more then 2 layer then it will be missy . Hopefully it will workThanks for your help and time I really appreciate it

author: coromonadalix
author_rank: Super Contributor
timestamp: February 22, 2024, 12:55:48 pm
content: don't double post for the same ic subject .....
Need a little help understanding this part of a SMPS - Page 1
Forum section: electronics / repair

author: secondlife
author_rank: Newbie
timestamp: August 31, 2021, 08:27:23 am
content: Hey all. After being mad for electronics back when Dick Smith used to sell electronic components I have recently got back into it as a bit of lockdown relief and have a SMPS on my desk from a active speaker I use for my music production. After looking at the schematics and doing a bit of googling one part of the circuit has me puzzled, I am guessing its a form of inrush current limiting but was hoping someone out there can confirm that or correct my thinking. It's on the AC side before the mosfets and is basically 4 diodes in parallel with a thermistor from the positive side linking in-between the 3rd and forth diode. I understand the Thermistor is there for current limiting but can not work out why it links where it does and what this achieves. Here is the link to the schematic.https://imgur.com/a/NAot5LQ

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 31, 2021, 08:50:49 am
content: Yes, inrush current limiting.The inrush current is caused by the charging of C7 and C8 which are on the "DC" side of the bridge rectifier formed by the 4 diodes.

author: TheMG
author_rank: Frequent Contributor
timestamp: August 31, 2021, 05:54:34 pm
content: Yes it's for inrush current limiting.It's just that the schematic is drawn a little bit weird (not the typical diamond-shaped arrangement for the 4 bridge rectifier diodes), but it's literally going like this: AC input -> thermistor -> bridge rectifier -> filter capacitorsNothing at all unusual about the design other than the way the schematic is drawn.
Need info or a picture from de back of the frontend board from the R&S CMU200 - Page 1
Forum section: electronics / repair

author: Ct1jrz
author_rank: Contributor
timestamp: May 21, 2019, 10:59:35 pm
content: Hello every one.I have an R&S CMU200. Some time ago when I was repairing a HF transceiver, I transmit 100W to the CMU200 frontend.I open it and discovered some burned resistors in the back of the frontend board. I don´t know if there is more damaged components, but at least I want to start to replace the damaged resistors.The problem is that i cant see their values!!!!I do not have the schematic, and i think it´s to difficult to find it.But maybe someone have some pictures from the board where I can see the values. Or some info about them.Thank you all in advance.Sorry about my poor englishHere two photos from the parts
Need a schematic for a Weller WR3M or WR3ME. Mine failed on ch1 - Page 1
Forum section: electronics / repair

author: mkinn
author_rank: Contributor
timestamp: May 31, 2025, 07:24:39 pm
content: I desperately need a schematic/parts list for a WR3M or WR3ME, please! I've NEVER been able to find either for ANY Weller products. Must be for authorized repair centers or internal Weller use only, if they even exist. I found the block diagram and exploded view/parts list, not really helpful. Also, is there somewhere other than Weller to purchase internal parts for Weller? Not here in Birmingham AL!My station just had a short on ch 1. It stays on even after the temp is reached, and will destroy an iron connected to it if I don't shut it off right away. Iron glows red hot! Hoping it's a shorted output trs. The green LED comes on immediately when an iron is plugged in, never goes out. Channel 2 and 3 (and pumps) work fine. The main board part # is T0058759722N, but it's $800.00! I'll try and fix mine before I spend that!Also, I'm looking for a schematic for a WRS2000 or WMA3V, which is the same thing. Anyone looking for an owner's manual for the WRS2000 will not be able to find anything useful ANYWHERE, but just Google WMA3V service manual and hopefully you will find a WMA3V.pdf, which IS the User manual in the usual 20 languages, and does have the block diagram and exploded view/parts list.

author: mahi
author_rank: Regular Contributor
timestamp: June 01, 2025, 04:22:37 pm
content: I've never seen a schematic or service manual for the Weller WR family. I'm afraid you'll have to do some reverse engineering. Since the other channels work fine, I don't think there's anything wrong with the digital circuitry. The problem is most likely at the triac(s) or the surrounding logic. This should be fairly easy to reverse engineer.Each channel is identical with one exception: Channel 1 has one extra triac.Channel 12x triac for 24V tools2 x triac for 12V toolsChannel 21 x triac for 24V tools2 x triac for 12V toolsChannel 31 x triac for 24V tools2 x triac for 12V toolsThe second triac for the 24V tools on channel 1 is to support the HAP 200 hot air handpiece that has two heaters. The second triac for the 12V tools is to support the second heater of tweezers.You might find some useful information inWeller WR 2 rework station - teardownandWeller WR3M /WD3M Triacs sterben(German).
Need a screen for a agilent 33210a - Page 1
Forum section: electronics / repair

author: Karnathe
author_rank: Contributor
timestamp: February 17, 2025, 02:38:33 am
content: Does anyone know how to get a screen for an Agilent 33210A function generator? I've been looking around on eBay and online but nothing.I know this family of instruments have similar (the same?) screens, so close models I think would be fine.Thank you!

author: coromonadalix
author_rank: Super Contributor
timestamp: February 17, 2025, 03:50:54 am
content: any markings on the lcd ??agilent pn should be this one : 2090-088618 pins + 3 for the ccfl33220 schematic, same parthttp://www.dasarodesigns.com/wp-content/uploads/Agilent%2033220A%20Service%20Manual.pdf

author: Karnathe
author_rank: Contributor
timestamp: February 19, 2025, 09:42:21 pm
content: Here you are, thanks for the help.

author: coromonadalix
author_rank: Super Contributor
timestamp: February 20, 2025, 08:40:51 am
content: this number give a very different lcd and size?have you sent a request to Keysight ?WD xxxx would be Wintek company, google fuu still gives the wrong lcd size ??

author: voltsandjolts
author_rank: Unknown
timestamp: February 20, 2025, 10:24:27 am
content: Wintek WD-G2506VHmmm, seems like a problem, hard to find anything about this lcd.Try looking on the lcd for the controller chip number?To get going now, you could use the ethernet port on back of the unit and write a small app for control?https://pymeasure.readthedocs.io/en/latest/api/instruments/agilent/agilent33220A.html

author: squadchannel
author_rank: Frequent Contributor
timestamp: February 20, 2025, 10:53:02 am
content: https://www.mikrocontroller.net/topic/123QuoteQuoteMOD:it maybe the much bigger WD-G2506 “M” model.

author: coromonadalix
author_rank: Super Contributor
timestamp: February 20, 2025, 01:06:52 pm
content: yeah seen all of them too, since this lcd board is a carrier of the real lcd who has 24 pins .... and given description ... it's a matter of finding what is the controller ... size seems right at 256*64

author: Karnathe
author_rank: Contributor
timestamp: February 21, 2025, 12:57:08 am
content: Thank you for the help ya'll. That is the correct screen, has to be since it's the one from the unit. I will look around for the screen. The actual issue with the screen is the backlight is sometimes working sometimes not, and the screen has vertical lines heavily destroying the image. Oddly the capacitor on the backlight driver was very hot, but tests fine. Not sure what that could indicate, I know nothing about cfl lights.
Need advice for replacing the RTC/CMOS/Battery Ni-MH of a Toshiba Z930 ultrabook - Page 1
Forum section: electronics / repair

author: touchatout
author_rank: Contributor
timestamp: April 02, 2025, 10:16:27 pm
content: Hi,I need to replace the RTC battery of a Toshiba Z930, which voltage falled around 2,68 V.The battery is not common, Ni-MH, and therefore quite expensive, around 20$ to 30$, plus the cost of an international shipment as I cannot find it easily in my country, so globally around 30$ to 45$.My soldering equipement let me easily connect the plug of the weak battery to the cable of another laptop CMOS battery.I have in stock Lithium cells, also delivering 3V, in CR1632 and CR2032 format.What is holding me back from adapting them is that the laptop controller that charges/uses the RTC battery is presumably designed for a Ni-MH one.(Page of the maintenance manual: thehttps://www.manualslib.com/manual/813546/Toshiba-Port-G-Z930.html?page=34#manual)I have a tin soldering station, but not a spot welder one.Is there a model of Ni-MH button cells (Panasonic or else) with presoldered legs from which I could easily build a replacement battery?Thank you.

author: u666sa
author_rank: Frequent Contributor
timestamp: April 03, 2025, 03:56:35 pm
content: You need this chrome extension calledAlitools Shopping Assistant. You search by picture. Plenty of batteries out there for about couple of bucks.Are you sure you are not able to push your battery with a power supply?
Need advice removing capacitor from ceramic substrate. - Page 1
Forum section: electronics / repair

author: rfdes
author_rank: Regular Contributor
timestamp: December 02, 2022, 12:25:18 am
content: I have a small ceramic hybrid with a suspect, leaky surface mount cap. It appears like it was soldered using silver solder (it looks very shiny) but I'm not 100% sure. The desire is to safely remove and replace this capacitor for testing and/or replacement. I would appreciate any help in how to best approach this task. My thought is to use hot air and paste as opposed to a solder iron and 15 mil solder (smallest I have). I also don't know what the recommended temperatures should be used during the rework. This hybrid has no active parts, just passive parts and thick film trimmed resistors. There are also some gold plated microwave structures.I could use some advice from others with experience.ThanksJim

author: Swainster
author_rank: Frequent Contributor
timestamp: December 06, 2022, 05:19:57 am
content: My experience with ceramic hybrids is that they are horrible to work on. The "tracks" appear to be more like conductive paint than copper foil, and will peel off as soon as you even look at them wrong. I was swapping a SO-8 transistor array in a TRMS converter, using a solder flood technique i.e. filling both sides of the SO-8 package with solder then removing the package while both blobs are still molten. I suspect that with the thermal conductivity of the (alumina?) substrate, this didn't work so well, hence a couple of the pads following the transistor array. Next time I do this, I intend to try using a plate to bring the whole hybrid up to temperature. Not sure what this will do to precision resistors though - nothing good I should imagine. Hot air seems like worth a try

author: coppercone2
author_rank: Super Contributor
timestamp: December 06, 2022, 06:01:31 am
content: can you grind it off with a smooth very fine diamond burr (thats placed against a diamond stone to get rid of high spots) and then solder over that ? with cooling
Need Advice Replacing QFP with E-Pad - Page 1
Forum section: electronics / repair

author: irobot
author_rank: Newbie
timestamp: October 24, 2024, 04:17:39 am
content: Need to replace a 176-pin thin QFP with an e-pad (ground pad) and looking for suggestions, or any tips on best way to do this.I always use the "drag" method with QFP's, using conventional leaded solder and controlled temp iron.I rarely come across having to deal with e-pads in my 40+ years of doing rework which includes fine-pitch SMD.Obviously need to use hot air for the e-pad.Do I use paste on pins and e-pad and "float" it into place with hot air, or what?I've already scoured YT looking for help.

author: ataradov
author_rank: Super Contributor
timestamp: October 24, 2024, 05:53:03 am
content: I did not need to do that a lot, so I have no idea how consistent the method is, but when I did it, I just used hot air to solder the pad and then drag soldered the rest of the pins. This let me check that the pas is actually soldered. The rest of the method is just just QFN - heat up the device, poke it a bit to make sure it settled, make sure pin alignment is still ok.It was a bit annoying to manipulate the large package, since it did not fit entirely into the field of view of my microscope, but I managed to make it work in the end.
Need an obscure Nakamichi amplifier schematic - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: April 26, 2019, 02:39:17 pm
content: Hi all-Anyone able to point me to an obscure schematic for a Nak amp? It seems I have an oddball version here.I'm working on one from the good old days and can't find docs that match this particular unit. The model is PA-7Aii but the boards donotmatch the service manuals I have found at the usual places (hifiengine, etc.).The manuals I have found say there is only one internal pot and it sets bias. No offset adjustment exists. But that's not what I see in my unit. Mine has 2 trimpots (presumably for offset and bias) but it seems both pots strongly affect both parameters so it's a bit of a challenge to sort out how to adjust it. Any insight is most welcome. Thanks!

author: floobydust
author_rank: Super Contributor
timestamp: April 27, 2019, 06:55:44 pm
content: PA-7, PA-7E have two trimpots, one for bias current and another for DC offset.PA-7_II, PA-7A_II, PA-7E_II has one trimpot for bias current.But I found a "PA-7E_II 6" pic with two. Maybe post pics of the region with the mystery trimpots. Nakamichi may have rolled back to two adjustments on later board revs. PCB Part No. BA07259A or BA07446A?Sometimes there are issues with mismatch in the JFET input diff amp. I'm not sure how good the dual 2SK240 was in production, they may have done an update to the PCB and design that is not in the available schematics. Other times I have seen an extra balance trimpot for the JFET front end. That adjustment is not for the faint of heart. A noisy trimpot can cause drama when at the JFET sources.

author: ebastler
author_rank: Super Contributor
timestamp: April 27, 2019, 08:10:00 pm
content: This site claims to have the service manual for the PA-7A II:http://www.hifi-manuals.com/Nakamichi/PA-7-A-Mk2/downloadsIt's supposed to be free, but you need to create an account, which I have not done. So I can't vouch for it.

author: cvanc
author_rank: Frequent Contributor
timestamp: May 01, 2019, 01:09:44 pm
content: Floobydust-Thank you; the photo you posted appears to be the same board version I have. Can you share where you found it?Ebastler-Thank you too; that version of the manual is the closest I have seen yet (but still not an exact match).Appreciate the input!

author: floobydust
author_rank: Super Contributor
timestamp: May 01, 2019, 08:01:14 pm
content: The image is fromHiFi Shock Museum, I got lost in the amplifier porn looking at images of this Nakamichi. There are many PCB pics out there.It's the only amplifier I've seen that does not use emitter-follower output stage. It's common-collector with no overall loop feedback, just local feedback and under 0.05%THD is impressive. But 62lbs
Need assistance on HP 4291b impedance analyzer - Page 1
Forum section: electronics / repair

author: Saw
author_rank: Newbie
timestamp: August 11, 2024, 02:59:57 pm
content: Hello and hi everyone.. i need help with an HP 4291b impedance analyzer, been stuck at startup screen just showing 'internal test in progress'..So far nothing i did can change or get a response from the machine, i have kept it on and waited more than 24hours as well.. thank you in advance

author: MathWizard
author_rank: Super Contributor
timestamp: August 12, 2024, 05:33:27 am
content: Does it have a warranty ? I see it's quite expensive and out of my leauage.But I'd open it up, and see what the motherboard is doing. Check the PSU section too. A lot of it is probably like a mini-PC, and has a strict startup routine. What happens when ram and rom go wrong.I'd want to know if just the screen locks up, would you normally hear changes after pressing buttons, like relays?There's probably some microcontroller or other such chip, that should be sensing this problem, and you would think, would want to time out and reset. Does it do a RAM check and just get stuck and never finish? Does some circuit or chip somewhere not initialize, and rest of it sits there waiting forever ?Here's a service manual, there's a lot pf troubleshooting sections in there, if you want to open up the HP.

author: _rushin_or_draggin_
author_rank: Regular Contributor
timestamp: August 16, 2024, 06:14:29 pm
content: I would start with the Service Manual and see if you can get anything from it. Chapter 10 shows what all the tests do. In chapter 5 it says the startup sequence goes through tests 1,4,5,6,7, 9-16. Maybe it is getting hung up on one of the tests? I see test 1 tests a lot of things. Maybe start there? I have attached the service manual. It may not match up with your serial number, but it should have most of the information you'd need.
Need assistance with Pro'sKit ss-331H wiring - Page 1
Forum section: electronics / repair

author: PCMcGee
author_rank: Newbie
timestamp: May 27, 2021, 10:30:43 pm
content: Hello,New user to the forums, though I've been watching the YouTube for many years. I recently purchased a Pro'sKit SS-331H and when I received it there was a broken wire inside. I have been watching YouTube videos, including the EEVblog review, and looking for whatever documentation I can find on the interenet to determine where this wire is connected to without any success. I thought it might be worth a try to ask here. If anyone has this desoldering station and could take a look inside and tell me where this wire belongs, it would be greatly appreciated. The wire leads from the third pin on the board, as pictured, to somewhere on the DIN connector to the desoldering gun, (I think). Upon inspecting all the connections to the DIN connector, I can't determine which part it became disconnected from. It just isn't obvious like I would think it should be.Thanks in advance for any help you can provide.

author: PCMcGee
author_rank: Newbie
timestamp: May 28, 2021, 01:23:06 pm
content: Yes

author: Andy Watson
author_rank: Super Contributor
timestamp: May 28, 2021, 04:33:48 pm
content: HiI traced out the circuit of the SS331B here:https://www.eevblog.com/forum/testgear/using-a-proskit-ss-331h-on-110v/Note, that's the B version. I understand that the H version is very similiar but updated, including an extra connection to the iron socket/plug.

author: PCMcGee
author_rank: Newbie
timestamp: May 28, 2021, 08:46:42 pm
content: Thanks I think this will be helpful for me. I'm not sure how I missed this when searching the forum but, thanks for directing me to the information, it's exactly what I was searching for.
Need box header for Denon AVR-X4300H - Page 1
Forum section: electronics / repair

author: Bargainhunter
author_rank: Regular Contributor
timestamp: May 05, 2019, 10:55:18 pm
content: Denon no longer has this part. The Part number is CJP13GI281Z and is described as a 13 pin header 1.25mm straight B to B. It has two rows 7 x 6.. Male.The unit was damaged in shipping ahd the pins were bent and broken off.Does anyone know where I can purchase a replacement? I tried DK and Mous...If not, has anyone ever repaired a box type header?
Need help buying or making lead extensions - Page 1
Forum section: electronics / repair

author: SquattingDog
author_rank: Contributor
timestamp: November 06, 2019, 09:53:38 pm
content: Since I haven't a clue how to make or where I might be able to buy, I'd like to find or make some extension for these. A male plug by female, so I'm able to extend these 24 inches or so. Suggestions are welcome.Regards,-JW:
Need clamping screw - Page 1
Forum section: electronics / repair

author: bob91343
author_rank: Super Contributor
timestamp: January 20, 2020, 05:52:19 pm
content: I picked up a stand fan SKY3865 that is missing some parts. The display is gone, which is no big deal, but there is a screw missing and it's a thread I don't know. It's the knob and screw that clamps the motor assembly to the vertical post. So now the motor wobbles on the stand and I'd like to find a bit of hardware to put in there.It's bigger than 1/4-20 and I think it's metric. I left a msg online but the factory insists I prove I am the original buyer (which I am not).Anyone know about this?

author: JacobPilsen
author_rank: Regular Contributor
timestamp: January 21, 2020, 04:25:22 pm
content: M8x1.25 is the most common metric screw "bigger than 1/4-20".M6x1 is smaller.And M7x1 is pretty uncommon.If you can't buy it from your local store, buy it online.Sometimes it's much easier.What about lenght ?

author: jpanhalt
author_rank: Super Contributor
timestamp: January 21, 2020, 06:12:48 pm
content: Does the screw go into a proper nut or pressed sheet metal. In the latter instance, I have seen Whitworth threads (55° included angle) used on a Chinese import. Whitworth screws are hard to find. Their dimensions are in inches.

author: bob91343
author_rank: Super Contributor
timestamp: January 21, 2020, 07:20:46 pm
content: The screw goes into a plastic affair. There are only three or so threads so I can see why the screw has been lost.I may try to fit a 1/4-20 with nut, depending on how much clearance there is. I just figured I'd ask in case someone had something that would work. I could even glue the parts together, and break apart the glue should I need to disassemble it.The whole fan is a piece of junk. I don't recommend it. I picked it up free on Craigslist and it's barely worth the gasoline to do that. I think it goes for around $50 - save your money.Update edit: Problem solved! I fitted a 1/4-20 bolt with nut that perfectly holds in the slot. It's needs a screwdriver to loosen but I can't imagine needing to do that unless I am moving, which I am not.

author: andy3055
author_rank: Super Contributor
timestamp: January 21, 2020, 07:50:01 pm
content: Replace the nut with a butterfly nut for easy adjusting.

author: bob91343
author_rank: Super Contributor
timestamp: January 22, 2020, 06:18:24 am
content: I thought I might somehow mount a large knob to the bolt and then it would be almost as it was designed. But my solution does everything I need and I am fine with it. Further, with a bolt I can can tighten it more for better security.As I said, a lousy design. The heavy motor and, actually, all the moving and controlling parts, are supported by this one bolt. In time, without a locking device, it will loosen and cause wobble and thus shorten the life. And make noise.On the other hand, it's kind of cool looking. It has some useless functions as well, but they were struggling to add value. My guess is that the unit won't last long, maybe motor or bearing failure, who knows. For now, it works.
Need dataheet for Silergy SYT664 - Page 1
Forum section: electronics / repair

author: fzabkar
author_rank: Super Contributor
timestamp: December 09, 2023, 12:55:39 am
content: I found this datasheet for a Silergy SYT664, but the link has expired.https://www.geckor.com/static/upload/file/20220809/1660026921692877.pdfAll I have left are Google's cached text-based copies.https://webcache.googleusercontent.com/search?strip=0&q=cache:https%3A%2F%2Fwww.geckor.com%2Fstatic%2Fupload%2Ffile%2F20220809%2F1660026921692877.pdfhttps://webcache.googleusercontent.com/search?strip=1&q=cache:https%3A%2F%2Fwww.geckor.com%2Fstatic%2Fupload%2Ffile%2F20220809%2F1660026921692877.pdfCan anyone find the PDF? Thanks.

author: ArdWar
author_rank: Frequent Contributor
timestamp: December 09, 2023, 01:04:13 am
content: https://www.visvie.com/static/upload/file/20220809/1660026921692877.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: December 09, 2023, 01:41:16 am
content: Thanks very much.I notice that the pin numbering is clockwise. Strange ...BTW, SYT664 (marking BJRxyz) seems to match the pinout of the BPKxyz chip on this SSD:https://tpucdn.com/ssd-specs/images/d/1266-pcb-back.jpgDo you have any idea which IC that could be?Or what about the "41853" Chip? I suspect that this could be a quad PSU supervisor IC.
Need Electrical Schematics for Stanford Research SR430--Not on SRS Website - Page 1
Forum section: electronics / repair

author: Flyingdancingfool
author_rank: Newbie
timestamp: September 08, 2022, 04:49:26 pm
content: Greetings!My Stanford Research SR430 "died" and I am trying to revive it. I've traced the first problem to the power board (labeled SR002). I found two voltages amiss, a -15 V (measured -5.0) and a -5.2 V (measured -4.1). The cooling fan doesnt work (drive voltage off).(1) I plan on replacing the electrolytic capacitors(2) It would be good to have real schematics(3) I know about Dave's SR430 teardown and I watched the video several times.The electrical schematics are*not*in the downloadable manual on the SRS WebsiteCan anyone help me with electrical schematics? I need drawings.Thank you!Kenn

author: edpalmer42
author_rank: Super Contributor
timestamp: September 08, 2022, 08:20:16 pm
content: AFAIK, Stanford Research never includes schematics in their downloadable manuals. However, if you buy a hardcopy of the manual, all schematics are included. Maybe reach out to them and see if that's still true and how much a manual would cost.Ed

author: coppercone2
author_rank: Super Contributor
timestamp: September 08, 2022, 11:53:10 pm
content: srf is something that you might not feel ripped off buying a schematic for honestly

author: Flyingdancingfool
author_rank: Newbie
timestamp: September 09, 2022, 08:16:28 pm
content: Hello!Thank you for the response.I called SRS and made an inquiry regarding manuals, schematics, parts, etc. The gentleman I spoke with said support was not available. No schematics, etc.SRS phone support always makes me feel like an idiot (and I am not a complete idiot).I will fix the !@#$%^&* in spite of SRS intransience.Kenn

author: edpalmer42
author_rank: Super Contributor
timestamp: September 09, 2022, 08:38:42 pm
content: That's unfortunate, but I guess if they decide to drop support for an old piece of equipment all you can do is shrug.I'd suggest spending some quality time with Mr. Google. Check each and every pdf copy that you can find. There may be one copy somewhere online that was created by scanning a hard copy. It might have the schematics. I've successfully used that technique before with Stanford's PRS10 Rubidium Standard. In that case, the schematics were in a seperate pdf.There's also a sticky here in the repair section that lists many sites that have operation / servicing manuals. Some of them aren't accessible to Google so you have to check them individually.
Need help !(Hameg 504  scope sweep line not in the middle) - Page 1
Forum section: electronics / repair

author: cnqhdszq
author_rank: Regular Contributor
timestamp: April 11, 2020, 12:31:42 pm
content: I bought a 2 hand Hameg 504 scope .At the begining ,the powersupply unit does not work.After 3 day's work .it works fine now . but when I pressed "AUTOSET " the trace line is not in the middle ，it is deviation to left of centre. I must move it by the "X-POS" knob ,When I press "AUTOSET "again ,the trace move to the left again.When I open the "MANUAL ADJUSTMENT MENU" and select the "SWEEP GENERATIOR" it says"PRESS SECURITY KEY !"What should I do next? .

author: aqibi2000
author_rank: Regular Contributor
timestamp: April 11, 2020, 01:56:51 pm
content: That is a nice scope!

author: coromonadalix
author_rank: Super Contributor
timestamp: April 11, 2020, 02:00:49 pm
content: User manual if it helpshttps://cdn.rohde-schwarz.com/hameg-archive/HM504-2_english.pdfhttps://elektrotanya.com/hameg_hm504_oscilloscope_deutsch_um.pdf/download.html

author: cnqhdszq
author_rank: Regular Contributor
timestamp: April 12, 2020, 02:58:41 am
content: thanks !!
Need help adjusting the Gw APS-9501 - Page 1
Forum section: electronics / repair

author: Alex06
author_rank: Contributor
timestamp: December 09, 2019, 10:32:08 am
content: Hello.I have AC POWER SOURCE APS-9501. For a long time he served me. And at one time, he took the testimony of U and I on the ADC, although the output in tolerance was measured by an external device.I took the instructions and found in it the adjustment (calibration) of the ADC readings.I managed to make an indication of U, but I didn’t.I don’t know how to configure which buttons.Need help.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: December 11, 2019, 06:21:09 pm
content: So, if I'm correct you are trying to calibrate the readings on it. How much is it off? Is the error consistent over the all the frequencies?I have the same one, let me check the readings on mine.So, I understand you are going through the calibration and you stumble upon some kind of trouble?

author: Alex06
author_rank: Contributor
timestamp: December 12, 2019, 06:20:53 pm
content: Hello.Everything is written in the instructions. Section calibration.My reading of l does not match.For example.~ 220V 50Hz., By overload.I have a current of 1A.The standard (external) shows 1A, and on the APS device itself 1.2A.

author: Alex06
author_rank: Contributor
timestamp: December 12, 2019, 06:33:11 pm
content: Can you change the current reading I up or down.If possible, write
Need help and manual for late version Tektronix 212 oscilloscope! - Page 1
Forum section: electronics / repair

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: May 23, 2025, 09:38:54 pm
content: Hi, Just got in a nice Tektronix 212 dual trace oscilloscope. It powers up OK but has a problem with triggering. If I display a 2 div P-P waveform and trigger on it it's fine but if I use the vertical position pot to move it up or down by more than a division or so it stops triggering. I can readjust and get it to trigger at the new position. This occurs using either channel 1 or channel 2 only as well as when in dual trace. If I put the same signal in both traces I can only get good triggering when they are sitting on top of each other. trying to move either traces position causes the triggering to fail. I down loaded the manual off of Tekwiki and started looking at the schematics and found another problem. All the on line manuals I can find are for the lower serial number units (<10xxxx). These units have the channel off switches built into the two vertical position pots. My unit SN B200967 does not have these pots or the legend by the pots showing off. Pulling the top cover does indeed show a different part number for the pots and no switches.So I'd first like to find a manual that is correct so I can troubleshoot further. Can anybody help there or advise on the problem? I also noticed that on the vertical mode switch that if you slide it up to the channel 1 position it internally covers up the auto preset hole! Do the older SN units do this also?You can also see the new vertical mode switch and relocated trigger source switch on the new versus the old SN PIX.Cheers!Corby

author: edavid
author_rank: Super Contributor
timestamp: May 23, 2025, 11:11:01 pm
content: Artek has the later manual for $12.50:https://artekmanuals.com/manuals/tektronix-manuals/I haven't found a free copy.

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: May 23, 2025, 11:20:35 pm
content: Thanks for the info! Ordered one from them.Cheers,Corby

author: ondraN
author_rank: Regular Contributor
timestamp: May 24, 2025, 11:22:21 am
content: I have 212 and 214 in my collection. Both are from the new series and do not have an on/off switch on the sync potentiometer. And both behave exactly like yours. Another special feature of them is that when the track is moved vertically, the horizontal position also changes. So if I have waveforms of the same signals, when I move one or the other track vertically, the phase seems to change. But it is intentional. I guess it improves the visibility of the signals in a two-channel display.
Need help determining Connector-type from pictures - Page 1
Forum section: electronics / repair

author: Echo88
author_rank: Frequent Contributor
timestamp: July 19, 2019, 11:22:22 am
content: Hi,i want to find the manufacturer and name of the following circular 3pin-connector, which is used as the external power connector for Fluke 732A references.Maybe someone here knows it and can give a hint:https://xdevs.com/doc/Fluke/732A/732A_5/imgp/732a5_rear_1.jpgupper right is the 3pin jack which i meanhttps://pasteboard.co/IoFZX0G.pngpicture of the plug, that i want to find and buyhttps://pasteboard.co/IoG0lwD.pngpicture2https://pasteboard.co/IoG0zsN.pngpicture3Seems to not be a high quality connector, more like a plastic mini-XLR. Just substituting the jack against a more common connector is sadly not an option.

author: mikerj
author_rank: Super Contributor
timestamp: July 19, 2019, 11:35:20 am
content: No marking to indicate manufacturer?These look similar:https://www.smithsinterconnect.com/products/connectors/circular/d-series/

author: Echo88
author_rank: Frequent Contributor
timestamp: July 19, 2019, 05:21:26 pm
content: Indeed, other names seem to be Hypertronics and Hypertac.https://www.datasheet.directory/index.php?title=Special:PdfViewer&url=https%3A%2F%2Fdatasheet.iiic.cc%2Fdatasheets-1%2Fhypertac%2FD01PB306NT.pdfThink ill need D01PB306NT and YSK006--011AH/YSK006--089AH. Now i gotta find a distributor who stocks it and would sell it to me...apparently difficult according to digipart.

author: syau
author_rank: Frequent Contributor
timestamp: July 20, 2019, 12:12:25 am
content: Quote from: Echo88 on July 19, 2019, 05:21:26 pmI am also looking for it but not available. Please let me know if you find a distributor or we may able to share the quantity if they have minimum order.

author: dacman
author_rank: Frequent Contributor
timestamp: July 21, 2019, 07:39:37 pm
content: Here's a distributor owned by Warren Buffet:https://www.ttiinc.com/content/ttiinc/en/apps/part-detail.html?mfrShortname=&partsNumber=D01PB306NThttps://www.ttiinc.com/content/ttiinc/en/apps/part-search.html?searchTerms=YSK006&systemsCatalog=&x=true
Need help diagnosing fault with Panasonic KX-TGA520 handset - Page 1
Forum section: electronics / repair

author: bte
author_rank: Regular Contributor
timestamp: November 10, 2024, 11:33:19 pm
content: Hi all,I need help figuring out why one of the handsets of our Panasonic KX-TG5240 phone developed a strange fault. I attached a small clip to show the problems (I had to put it in a zip archive since forum software doesn't allow attachments with mp4 extension):1- One of the screens is dim and there's a lot of flicker.2- Cursor-like blinking (like when entering a name or number) happens randomly in various screens.I first tried a new battery but that didn't help. Then I decided to open the handset and check the circuit. While there, I tried powering the handset from a RD-6006P power supply, set at 3.8V and 400mA. This also didn't help, either (the handset never consumed more than 150 mA and this is how I made the clip attached to this post).Then I thought "maybe the caps are causing the issue". I measured the two main caps using DER-EE DE-5000 at 100 Hz. 330uF read about 288 and 100uF read about 84 so I changed them both (the phone is about 20 years old). The blinking issue improved a bit but it didn't go away (the clip is made after the replacement). Nothing changed with respect to the dimming/flicker issue. I also attached a picture of the circuit board.I would appreciate any insight as to the direction I need to take from here.
Need help explaining how this circuit works - Page 1
Forum section: electronics / repair

author: laban93
author_rank: Contributor
timestamp: July 28, 2019, 02:46:45 pm
content: So i just reverse engineered this circuit board from a failed safety lighting fixture (used when cleaning tanks on ships and rigs), and got it working again after i located and changed a faulty NPN. But i do not understand the working principle of the circuit. It's fed from a 42VAC source, and all the winding taps (1 to 10) is located on the primary side of the transformer. The secondary side has two windings connected to the 36W compact fluorescent lamp (not drawn). Also why is there a "mutual inductor"?

author: PKTKS
author_rank: Super Contributor
timestamp: July 28, 2019, 03:52:47 pm
content: Your draft (assuming you have at least 90% confidence) looks like RCCRCCs or Ringing Choke Converters are a proper class of ( CHEAP! very CHEAP! )self oscillators with a long list of applicationsAssuming that as we have no controller IC no SCRs not even MOSFETsRCCs are designed to induce BJT to unstable operation (aka ringing)using the transformer coil... several designs possible.They are bad, unreliable, error prone and present great deviationover time.but they are CHEAP. Nothing compares.and they work as long as the choke rings...BTW some magic voodoos and tricks are necessary to keepthese things properly ringing over time... as components age.Paul

author: james_s
author_rank: Super Contributor
timestamp: July 28, 2019, 04:13:45 pm
content: I think what you are calling the mutual inductor is a common mode choke, it's used to prevent noise generated by the circuit from being fed back into the electrical system where it could interfere with other devices.

author: laban93
author_rank: Contributor
timestamp: July 28, 2019, 06:16:23 pm
content: Aah, i assumed it was a mutual inductor, both poles are wound around a torodial ferrite core, and a quick google search told me mutual inductor, but i am in no way, shape or form educated in this kind of component repair, so thank you both for helping out! And no, there is no other IC's. I thought the choke usually was on the incoming supply wires? Anyway this is supplied from a small portable insulation transformer.

author: jdragoset
author_rank: Frequent Contributor
timestamp: July 28, 2019, 10:37:34 pm
content: Likely a saturable core oscillator with the main transformer winding's 5,6,7 providing feedback to the transistor bases.Frequency may be set by the RC network connected to terminal 5.
need help finding a zener diode MMSZ5252A - Page 1
Forum section: electronics / repair

author: rostomzerrougui
author_rank: Newbie
timestamp: May 23, 2024, 07:11:36 pm
content: hi every oneafter a diagnosis on a laptop mother board it appeared to be this zener diode MMSZ5252A is shortedthe laptop is a HP probook 6470bi need help to find the diode on other motherboardshere is the location of the diode (see attachement)
Need help finding replacement SMD fuse - Page 1
Forum section: electronics / repair

author: m11k
author_rank: Newbie
timestamp: August 22, 2020, 08:12:47 pm
content: Hi. Looking for some help finding a suitable replacement. I blew a fuse on an LCD backlight inverter for a laptop, and need to find a replacement. I don't really feel comfortable jumping it with a wire. The markings seems to say "2A 5Z". It is size 1206. See attached pics. If it matters, the voltage on it relative to ground is 20V. Looking at sites like digikey, I see slow blow, fast blow, or regular? Will any old 2A fuse do? I don't need an identical replacement, just something functionally equivalent. Thanks in advance for any help!

author: bdunham7
author_rank: Super Contributor
timestamp: August 22, 2020, 09:07:49 pm
content: Just ran into this issue with a backlight inverter. In my case, the fuse used was '2A', but was rated to blow (in 5 seconds) at 2A and had a continuous rating of only 800mA--and the device used 950mA. I replaced with a 1.25A fuse with a 2.5A 'fusing current', IOW, the current that blows it right away. The same would likely work for you. I doubt your backlight actually draws 2 amps or anything close, but I'd jump the fuse with an ammeter and see. If it is 700-1000mA, the fuse I used will be about right.I have a few now, I ordered these:https://www.mouser.com/ProductDetail/652-SF-1206FP125-2and there's a guy on eBay that sells 3-packs and mails them cheaply.https://www.ebay.com/itm/1-25A-63V-3pcs-J-Fuse-1206-SMD-SMT-Very-Fast-Acting-Littelfuse/121610040584?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

author: m11k
author_rank: Newbie
timestamp: August 23, 2020, 01:28:00 am
content: Thanks. That's a good suggestion. The display backlight specs says power draw is 4.2W typical, so 1.25A at 20V should be more than sufficient rating (but still better than jumping it). I blew the fuse while testing a borrowed panel which happened to have a bent ground pin that shorted to Vcc on the power connector. Whoops.

author: aqibi2000
author_rank: Regular Contributor
timestamp: August 23, 2020, 09:13:25 am
content: There are always 2 fuses for this feed if it is LCD/LED laptopOne on the laptop motherboard near the connector and this one you found in the screen driver boardJumping this will be fine
Need help finding this Chip that I think is a TSSOP-20 - Page 1
Forum section: electronics / repair

author: Revo2Maxx
author_rank: Newbie
timestamp: April 10, 2024, 06:31:17 am
content: So this is the first PCB leading into my POE PTZ 25x zoom camera. The POE no longer works and the chip next to the Transformer EFD2027SR. The chip is a 20 pin that starts with WS. However because of the damage to the chip the rest of the info is missing.It is a Alibi Vigilant 25x 4mp AI camera. The camera still works if I use 12v power supply. However the location for this camera isn't close to a power outlet so I would rather repair the PTZ camera if anyone has some info about what the part is. Thank you in Advance.
Need help fixing a FSP450 PSU - Page 1
Forum section: electronics / repair

author: Asterix
author_rank: Contributor
timestamp: November 14, 2020, 09:00:01 pm
content: Hi!I have a PSU type: FSP450-40UGBBF.When connected to a motherboard the fans spin slightly.But turns off. I have measured the 5v rail.This was missing.I checked resistance it showed an open line on the 5V rail.The 12v shows around 300Ohm.After this i measured the wire wich was not broken.I checked the resistance in the pcb wich was an open line the first time.Now it is around 200Ohms.I thave the exact psu once more and i compared the measurements to each other.They Are in the same range. Nothing out of the ordinary here.But it still wont work.Is there someone who can tell me what i should measure?Or maybe has the knowledge of this type? or a schematic?
Need help fixing Advantest U3641 flickering screen - Page 1
Forum section: electronics / repair

author: pfm
author_rank: Regular Contributor
timestamp: July 13, 2019, 08:45:41 pm
content: Advantest U3641 works fine. It has a tilt LCD screen that you tilt up and down to change the viewing angle. Works fine in small range of tilt (downwards) but as soon as it is tilted in the upward direction the screen goes crazy. Its not exactly flicker but its more like how a crt horizontal rolling/sync issue looks like. See pics.Looking for any info anyone can provide on fixing this.Also, where can I find the service manual for this unit ? I cant seem to locate it on the web.Thanks!

author: eb4fbz
author_rank: Regular Contributor
timestamp: July 14, 2019, 03:57:06 pm
content: Sadly no useful service manual is available for this equipment. I have an U3661 and it looks like a damaged LCD cable to me. Good luck!

author: pfm
author_rank: Regular Contributor
timestamp: July 15, 2019, 05:05:31 am
content: I was afraid about that. How would anyone then find the part# of any part (like the lcd cable) ? Are parts like these even available for these units ?

author: DaJMasta
author_rank: Super Contributor
timestamp: July 15, 2019, 06:44:28 am
content: You're likely going to have to open it up to find out, but I know from working in some other advantest instruments that they tend to use fairly standard LCD modules, if you actually need a replacement, they should be available. Similarly, not many service manuals, if there is something, it's likely on KO4BB... and I only see a product brochure.First open it up and make sure your cable isn't just loose at either end. Then give it a good jiggle and see if you can replicate the issue with the same sort of thing. Then figure out if it's a cable or connector thing which is likely easy to fix, or if it has to do with the cables built onto the LCD glass, which would probably need a replacement if you can't use heat to reseat the attachment or similar.