hybridfree/eevblog-posts huggingface dataset:
Power Designs 2005A Oven Repair - Page 1
Forum section: electronics / repair

author: BarryBreaux
author_rank: Contributor
timestamp: February 18, 2023, 08:48:00 pm
content: Does anyone on here have any experience repairing one of the Power Designs Ovens?So I found that all the components in the oven have been overheated to the point that the casing around the resistors are cracked and fallen off. I suspect that the thermostat switch was not functioning correctly.Regards,Barry Breaux

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 19, 2023, 06:38:59 am
content: Did you take any photo of the crime scene?

author: BarryBreaux
author_rank: Contributor
timestamp: February 20, 2023, 01:22:34 am
content: Yes sir!

author: BarryBreaux
author_rank: Contributor
timestamp: February 20, 2023, 01:24:04 am
content: The other side.

author: BarryBreaux
author_rank: Contributor
timestamp: February 20, 2023, 01:31:49 am
content: The bracket that holds the thermostat broke, I think this is why it cooked my components.

author: alm
author_rank: Super Contributor
timestamp: February 20, 2023, 01:34:52 am
content: Thanks for the pictures. Those are definitely some deep-fried resistors!

author: Stray Electron
author_rank: Super Contributor
timestamp: February 20, 2023, 01:44:46 am
content: There is at least one other thread on this forum about a tear down or a repair of the PD meters. I think only the PD meters with the stepped dials use the ovenized temp reference. I'm also fairly sure that there is an operators and a service manual online for the 2005 model.

author: BarryBreaux
author_rank: Contributor
timestamp: February 20, 2023, 03:06:54 am
content: Those toasted components all still worked somewhat. Off spec, but the power supply still worked. The controls were off by 40 mv. I also found the filter capacitor to be bad. This thing is solid!

author: BarryBreaux
author_rank: Contributor
timestamp: February 20, 2023, 03:00:01 pm
content: I found several users who have rebuilt their oven. One user was proposing using a micro controller to improve on the temperature control. I am very interested in knowing his final design! Of course I would like to hear any success stories!

author: exe
author_rank: Unknown
timestamp: February 20, 2023, 04:13:40 pm
content: Yeay, I'm curious too. I've a PD power supply, and those thermostat clicks are annoying. It shouldn't be too hard to implement it (I guess all it takes an opamp and a thermistor, but I'm lazy).

author: floobydust
author_rank: Super Contributor
timestamp: February 20, 2023, 06:40:30 pm
content: Power Designs 2005A schematic manualhttps://www.barbouri.com/2018/01/13/power-designs-2005a-precision-power-source/It looks like the TIC47 SCR 200V 0.3A which controls the heater fails short?

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 21, 2023, 04:29:27 am
content: I have now seen truly cooked components!
Power Designs Inc 1010T Manual - Page 1
Forum section: electronics / repair

author: Robbdoe1
author_rank: Contributor
timestamp: November 04, 2024, 01:51:26 pm
content: Hello. I bought a 1010T on Saturday at the hamfest and it has zero output. I’m looking for a proper manual for it? Any help is greatly appreciated.Robb

author: Robbdoe1
author_rank: Contributor
timestamp: November 24, 2024, 04:45:21 pm
content: Anyone? I’m still looking for this manual?
Power Designs T178797 2K-15 High Voltage Regulated DC Power Supply - Page 1
Forum section: electronics / repair

author: NSV11UP
author_rank: Newbie
timestamp: September 10, 2022, 04:08:09 am
content: I have a Power Designs T178797 2K-15 High Voltage Regulated DC Power Supply that I am trying to service.Power Designs after a number of mergers and acquisitions no longer has any web presence. In 1996 Power Designs acquires assets of Variac and Technipower, a manufacturer of military power supplies. “TECHNIPOWER LLC was formed January 1, 2003 following the acquisition of Integrated Power Systems LLC of Corona California by Power Designs (DBA Technipower) of Danbury, Connecticut. As of 2004, May 20 Power Designs website Website redirects to Technipowerllc.com with all references to Power Designs removed however at that time Technipower laboratory power supply line continued, preserving some Power Designs model numbers.Does anyone have any leads on where service manuals or schematic diagrams can be obtained for this out of production no longer supported unit?

author: HalFoster
author_rank: Frequent Contributor
timestamp: September 10, 2022, 11:04:29 am
content: I don't have the manual for the 2K15, but here are the ones for the 2K10 and 2K20 - hope they help.2K10:https://drive.google.com/file/d/1T6IN5XGF7OViJXBKd6H326PIFuVWmlU4/view?usp=sharing2K20:https://drive.google.com/file/d/1zr1T9qnmXklf318ZLgX95L9mg2Cefpq_/view?usp=sharingHal
Power Fuse - Page 1
Forum section: electronics / repair

author: Farah
author_rank: Contributor
timestamp: May 01, 2024, 08:36:24 am
content: I am repairing a 220VAC to 110VAC converter that is used for a 100watt UV lamp. because of spark, the input fuse completely damaged. which fuse appropriate for this circuit? the damaged fuse and the circuit board are attached.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 01, 2024, 10:54:06 am
content: if you know the output voltage and current of this psu, or the total current ...you can summarize a value like this : from ohms lawex: 24vdc at 2 amps is 48 watts48 watts / 120vac would give 400 ma fuse, you could play safe with an 500masadly the fuse is the last thing to blow in a smps ...do you have writtings on the psu casing 100w is ok but do you have voltage somewhere ? if you wrote 220 to 120 vacit is : 100 / 120vac = 833 ma ?? an 1 amp would be okay ? i think unless you have other problems

author: Farah
author_rank: Contributor
timestamp: May 05, 2024, 07:10:42 am
content: Thanks for your Reply.The output of this PSU is only used to turn on a 100 watt/110VAC UV lamp (Mercury). The power supply of the lamp fan is from another board. There is no information on the body of the device, board, etc.
POWER LOGGER FLUKE 1735 DOES NOT CHARGE BATTERY - Page 1
Forum section: electronics / repair

author: EDER
author_rank: Contributor
timestamp: March 12, 2024, 05:35:37 pm
content: Hello friends of the community, please I would be grateful if you could guide me with the repair of my equipment, the problem is that the battery does not charge, I checked the electronic card and found this burnt device, when desoldering it it broke into two parts, I cannot identify what type of device it could be, please if anyone has this equipment I would be grateful if you could tell me the device code. Thank you for your time.

author: Ugur
author_rank: Regular Contributor
timestamp: March 13, 2024, 06:45:09 am
content: Hi,BYD77B

author: EDER
author_rank: Contributor
timestamp: March 15, 2024, 03:45:34 am
content: Gracias por el apoyo.
Power Supply repair need help - Page 1
Forum section: electronics / repair

author: Andbro
author_rank: Regular Contributor
timestamp: July 23, 2019, 11:17:08 am
content: Hi,I have an old power supply built with Lm723 and 2N3055. The transformer is dead.What's the best solution for fix1- Replace the transformer by a new?2- Replace the transformer by quality SMPS like Mean Well or CUI?Thanks

author: firewalker
author_rank: Super Contributor
timestamp: July 23, 2019, 12:20:32 pm
content: Will the noise of the SMPS be an issue? What is the price difference?Alexander.

author: PKTKS
author_rank: Super Contributor
timestamp: July 23, 2019, 12:58:41 pm
content: Well i am aware that LM723 can implement even switch mode..But 99.99% LM723 topology is LINEAR.Using a 2N3055 BINGO! you have a LINEAR SeriesPassusually ranging from 2 to 20V - in rare cases 0-22You can make a new winding on your old TRAFO ..But depending on the price of any equivalent...I would not.Here i can find a brand new one almost the cost of rewindingPaul
power plug connector identification  help wanted. - Page 1
Forum section: electronics / repair

author: chapai
author_rank: Newbie
timestamp: September 20, 2022, 06:45:49 am
content: I get a microscope for smd work and plan to add an extra illumination light.the easiest way to use the same power supply and connector. 6v 1.2a for led light should be enough. Idea was to buy illumination ring from ebay or aliexpress and then slightly modify it.Looking for help from the community to identify the plug , so i can try to buy another one. It is probably obsolete but who knows?On the bottom embossed "Satoparts Japan".

author: fzabkar
author_rank: Super Contributor
timestamp: September 20, 2022, 07:56:31 am
content: Have a look on the Wayback Machine:https://web.archive.org/web/20220000000000*/http://www.satoparts.co.jp/Some years have a "discontinued items" under the products category. I couldn't find your plug, but you may have better luck, especially if you can determine the year of manufacture.

author: chapai
author_rank: Newbie
timestamp: September 20, 2022, 08:50:23 am
content: thanks for the link. unfortunately unsuccessful search.I am not familiar with connectors - but probably better to replace with something suitable.
Power plug for Agilent Handheld oscilloscope - Page 1
Forum section: electronics / repair

author: PCB-Andy
author_rank: Newbie
timestamp: November 09, 2022, 02:52:26 am
content: Hello to evreyone,I have a nice, nearly unused Agilent handheld oscilloscope but the power supply is missing. It uses an Agilent U1570A power supply which is not available anymore for a reasonable price.It is basically a simple 12V / 2A supply, no problem to find a substitute for it but i am struggeling with the plug. The plug is much longer than usual plugs, see the supply:https://www.distrelec.de/en/test-power-accessory-keysight-u1570a/p/17609450I woluld like to find such a plug and attach it to a common 12V 2A supply.Can someone let me know where i can find such a plug?I would like to find such a plug and not be forced to mess with the connector inside the scope.Any hints are most welcomeKind RegardsAndy

author: TheSteve
author_rank: Unknown
timestamp: November 09, 2022, 03:01:05 am
content: Ahh, yes the silly safety 2.1mm jack. I have a U1620A with no original supply myself. There are some regular 2.1mm barrel jacks that still fit. Another option is to find a reasonably narrow/long one and/or shave the outside down.I'd like an original plug myself if someone happens to have a source.I wouldn't mess with the scope itself, as I said it is easy enough to shave a plug down so it fits, much nicer vs hacking up the scope.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 09, 2022, 03:03:00 am
content: they resemble to the fluke scopemeter 90 series ac-dc adaptors ... just need to find the barrel size to be sure ??

author: PCB-Andy
author_rank: Newbie
timestamp: November 09, 2022, 03:45:39 am
content: "they resemble to the fluke scopemeter 90 series ac-dc adaptors"Unfortunetly not. I have a 99 Fluke scope too and i tried the plug, it does not fit, maybe if sanded down a bit to make it fit. I purchased the fluke scope with a 110V adaptor and found a 230V later on to use it here in Germany. So the 110V power adaptor was left over and it was my first idea to use it for the Agilent scope - but no luck. Thanks anyway.
Power resistors in LeCroy Waverunner HRO 64Zi PSU - Page 1
Forum section: electronics / repair

author: mssbid
author_rank: Contributor
timestamp: December 17, 2024, 05:27:00 pm
content: A LeCroy Waverunner HRO 64Zi didn't want to power on and I had to change some caps in its PSU.I also noticed a brown area on the bottom side of the PCB where two power resistors are connected.I checked their values: On gave me 12.4k (R13) and the other one 16k (R15). Apart from the fact thatthese are not very common values (especially for power Rs) they have the same colour markings.Therefore I am pretty sure these two guys have already degraded somehow.While the scope is already working perfectly again with the new caps, I would like to replace the tworesistors as well.If anyone has this PSU open or lying around it would be great if he could post the values of these two Rs.I have attached a pic of the two Rs and as well one of the whole PSU. The green circle shows the tworesistors and the red ones the caps that had to be replaced (in case anyone is interested).

author: Aheld
author_rank: Regular Contributor
timestamp: March 26, 2025, 07:17:48 pm
content: Hi mssbid,do you have some tear down pictures how to extract the PSU. My HRO 64 has same failure like you described and I expect to change caps, too.ThanksAxel

author: mssbid
author_rank: Contributor
timestamp: March 26, 2025, 07:58:38 pm
content: Quote from: Aheld on March 26, 2025, 07:17:48 pmNope. But it is quite a shitty design and I found some video which helped alot. Unfortunately, I didn't note down the link. I just tried to find it again but failed.Instead I just foundand, compared to the remnants in my brain :-), it seems to be quite accurate.One thing I remember when looking a the video: There is a multiwire cablewhich connects the display to the cpu board. I _think_ it is the black oneyou see at 0:54 (the one with 918426... on it). The insulation of its wiresis so crappy, that it falls of from just staring at it. I had several more orless blank wires close to the connector and I had to take great care whenI tried to isolate them again in order to not make it worse than it had beenalready...Apart from that I don't remember anything else special.Of course I am highly interested in the values of the two resistors -- maybeyou can an have a look at yours...

author: Aheld
author_rank: Regular Contributor
timestamp: March 27, 2025, 07:50:47 am
content: Thank you.This video answers a lot of question I had, yesterday.Br.Axel
Power Solve  Flexpower X4-3J3R5G  Modular SMPS info - Page 1
Forum section: electronics / repair

author: ingalopez
author_rank: Contributor
timestamp: January 09, 2023, 10:43:08 pm
content: I am trying to repair an industrial power supply from Power Solve, UK. It is composed by a primary; with a PFC; and different secondaries that fit on bays (up to 5) and allows to configure for your product needs. This one has three outputs (12V 10A + 5,0V 10 A; 24V 17 A; and 12V 25 A) and comunications.Now the primary PFC stage, is badly blown: Power mosfets; PFC controller L4981; Mosfet driver TC1413; and housekeeping power supply chip TOP 246G. I´ve identified the chips, but the power supply is quite complex and I am sweating a lot to reverse engineer the circuit. Something is not right yet (open traces...?), and I feel that replacing the components and trying it may lead to a expensive and shamefull explosion.Has anybody any circuits for this thing ?Thanks!!
SMD rework station YAXUN 881D - Page 1
Forum section: electronics / repair

author: BobLab
author_rank: Contributor
timestamp: February 07, 2022, 08:18:33 pm
content: Hello friends, I have this rework station yaxun model 881D, who only works the iron solder side, the air gun stopped to work and shows nothing on the seven segment display when you turn on the switch, but the fan from the air gun turn itself on even if you don't turn on the switch.What i did so far was unplug the the gun from the socket but the problem isn't in the air gun by the way, i've noticed the voltage regulator heats up a lot.. I never repaired one of this before so i hope some of you guys had the same problem and can help me, thanks !(The picture i grab from internet but the board is identical).

author: BobLab
author_rank: Contributor
timestamp: February 08, 2022, 09:17:39 pm
content: nobody?

author: thm_w
author_rank: Super Contributor
timestamp: February 08, 2022, 11:41:59 pm
content: Which regulator heats up?Did you carefully check the output voltage of the regulator (DC), and its ripple (AC), is it as expected?

author: BobLab
author_rank: Contributor
timestamp: February 09, 2022, 12:35:38 am
content: It's an L7805CV regulator, I don't have an osciloscope just a analog multimeter who only measure DC voltages and..i just measured the output of the regulator and gives the 5v output, but the regulator quickly heats up, So I removed the MCU from the socket and the heating process stops..Is the MCU shorted?

author: thm_w
author_rank: Super Contributor
timestamp: February 09, 2022, 01:35:24 am
content: "Heats up", but we don't know how much and if its an issue.If your analog multimeter can measure current you can measure how much current the MCU is drawing and see if its reasonable.Or if you have a 5V power supply, try using that to power it.Could be bad MCU, or could be whatever the MCU is trying to drive is shorted, causing increased consumption.

author: BobLab
author_rank: Contributor
timestamp: February 09, 2022, 02:20:24 am
content: Quote from: thm_w on February 09, 2022, 01:35:24 amHeats up a lot, I can't handle my finger there..Unfortunately the multimeter doesn't measure current, I've tried supply it with a external 5v power supply and the MCU heats up either, I'm trying to guess what peripheral must be shorted but without the schematics complicate things

author: BobLab
author_rank: Contributor
timestamp: February 14, 2022, 08:41:46 pm
content: well, I powered the MCU on a protobord to make sure if wasn't any peripheral shorted, but the MCU still heating a lot, Is the MCU bad, or maybe the voltage regulator is bad?? any guesses?

author: ss78
author_rank: Newbie
timestamp: February 15, 2022, 02:57:35 am
content: Unfortunately dead mcu

author: BobLab
author_rank: Contributor
timestamp: February 15, 2022, 03:12:25 am
content: thanks for you reply anyway!
Power Supply 305D - showing current with no load plugged in - Page 1
Forum section: electronics / repair

author: jensenpm
author_rank: Newbie
timestamp: November 02, 2024, 03:08:50 am
content: Hi all - newbie here. I have an issue with my WEP PS-305D power supply. It's showing a standing current of around 3.5A with no load plugged in. Voltage seems to work fine, although it could probably do with some finer calibration. I've had this issue for a few days - and other than the Current Meter being incorrect, it seemed to be working well enough to let me finish my couple of small tasks.Today I got around to taking the cover off to look for anything obvious. Couldn't see anything, but I wiggled a few plugs to see if there might be any loose connections - and then the no-load displayed current returned to zero as it should. I hate to declare it "fixed", so I was wondering if anyone could point me in the direction of which connection might be causing this. (I wiggled too many to know.)Anyone have any thoughts?Thanks

author: Harry_22
author_rank: Frequent Contributor
timestamp: November 02, 2024, 03:33:24 am
content: Hello!You made a typical mistake when diagnosing a malfunction. You can’t touch or reconnect anything until the reason is found. So it was scared away for a while. Now should wait for it to appear again.It would be great if next time you attached a photo with the current and voltage indicators and an external voltmeter readings as well.
power supply - Page 1
Forum section: electronics / repair

author: Jamfor
author_rank: Newbie
timestamp: February 22, 2025, 01:28:40 pm
content: I have an old minicraft transformer variable speed power supply. When I plug a drill or whatever into it what ever the speed I dial in it will suddenly go full speed . Any idea of what could be wrong. I'd hate to throw it as it is such a useful tool being able to plug three things in at once .

author: Ian.M
author_rank: Super Contributor
timestamp: February 22, 2025, 01:47:15 pm
content: That depends on exactly which one you have and the exact fault. If it suddenly goes from zero to full speed when you turn the speed knob that may be a defective potentiometer with an open-circuit track. If it *always* gives full speed no matter what the speed knob position, that is likely to be a failed (shorted) semiconductor.Its probably reparable, but without the model number, and maybe even you opening it up and taking good sharp closeup pictures of the board, its hard to help you further . . .

author: ledtester
author_rank: Super Contributor
timestamp: February 22, 2025, 03:09:16 pm
content: Is your triple-output controller a MB750?This video has a teardown of the single-output MB730 which is a thyristor-based speed controller:MiniCraft drill power supply repair -- ToyHackerhttps://youtu.be/qFX-gg-rUGoAt 6:36 in the video there is this schematic:(offscreen to the left is just a diode bridge coming from the transformer)The Spanish repair website URL mentioned in the video is:https://www.yoreparo.com/es/electronica/preguntas/866299/transformador-de-velocidad-variable-minicraft-mb730and has these pictures of the pcb:

author: Jamfor
author_rank: Newbie
timestamp: February 22, 2025, 11:37:18 pm
content: It is an MB0750 and when it first started acting up I could be using a drill at a set speed and then it would go full speed for a few seconds then back to the speed settings, but now it is full speed straight away.
power supply _ IGBT testing - Page 1
Forum section: electronics / repair

author: abode091
author_rank: Newbie
timestamp: October 13, 2023, 06:15:07 am
content: Hello,I'm repairing a power supply that has multiple IGBTs.The shorted IGBTs that has C-E resistance of couple Ohms are easy to know that they are broken.But what about those that have C-E resistance in the Kilo Ohms instead of Mega Ohms, should I consider those dead, damaged or correctly functioning?Note: the original C-E resistance is around 2.5 MOhms, now its around 8.5 KOhms.Thank you in advance.

author: jonpaul
author_rank: Super Contributor
timestamp: October 13, 2023, 07:28:07 am
content: A resistance meas at a few mA in an ohmmeter is not a reliable IGBT indicator.Also, shorted switches often are due to a more serious load or driver fault.Remove all the IGBT devices and test on a curve tracer or HV lab PSU.Place dummy loads on each driver and check driver outputs.Bon ChanceJon
Power supply blew cap after recap - Page 1
Forum section: electronics / repair

author: matt.zepess@gmail.com
author_rank: Contributor
timestamp: August 15, 2023, 08:21:38 pm
content: This pertains to a Sony laserdisc player specifically the mdp-550, I got no power, noticed a leaking cap and 3 diodes on the dc voltage side but close to the ac circuitry, recapped and replaced the 3 diodes, turned on once again and ran for maybe 30 seconds before a poof and some smoke. This time on the end of the dc side a cap exploded from the top appears I didn’t cross anything and the caps in the right orientation, what can be causing this? I wouldn’t expect heat as it’s only 30 seconds before failure. Maybe orientation on the board itself is wrong? I thought I checked but I also got a little side tracked. I do still have some of the old ones with the same value to try if nothing else. Part was obsolete on Digi-Key not sure if these things fail like this from simply being defective.

author: CountChocula
author_rank: Unknown
timestamp: August 15, 2023, 08:43:31 pm
content: Could be incorrect orientation (could be marked wrong on the board as well—it happens, but unlikely), incorrect cap voltage, or perhaps a short that's drawing too much current. What's the designator of the capacitor in the schematic?—CC

author: 807
author_rank: Frequent Contributor
timestamp: August 17, 2023, 09:53:32 am
content: Just for clarity. You changed a leaking capacitor in one location, but then a different capacitor blew at another location. Is that right? You also changed 3 diodes. Why was that? Did you change them for the exact same types, as you say that the part was obsolete on Digi-key?Can you take photos of the board? Perhaps some circuit references of the components you changed would help, as the schematics are available online.
Power Supply - Delay Output - Page 1
Forum section: electronics / repair

author: almamater
author_rank: Regular Contributor
timestamp: May 22, 2021, 11:27:42 am
content: Hello everyone, i bought another faulty LG Mini Hifi (to salvage the CDPlayer module for my original LG:here).But now i just only want to understand what could be wrong with this "other" power supply, nothing visually wrong with it but voltages take a long time to appear at the outputs.I only found thisservice manualand atpage 37they show all the Power Supplies variants for this LG Model, and this one doesn´t have StandBy Led, so some transistors are not present.Initially i didn't had any other voltage beside the +5V output, i replaced one transistor (theQ909(S8050 NPN)) and then i have other voltages but all with delay.I checked this components:IC901(DM0365RN) -> Testesd it with another oneIC902(TL431) -> Testesd it with another onePC901(OPTO) -> Testesd it with another oneDiodes (D910,D908andD909)-> All removed and tested, values seems Ok.THis board have 3 transistors S8050 (Q9009, Q905, Q911) and one B772 (Q908) and replace all with new ones.Check all the electrolytic capacitors and seems all ok.But voltages don´t appear without the ~2-3 minutes delaybut then it works all ok.Any idea what can cause the 'delay'?

author: wn1fju
author_rank: Frequent Contributor
timestamp: May 22, 2021, 09:42:43 pm
content: If you are sure all the caps are OK, could there be a cold solder joint somewhere that takes a few minutes as the board heats up? You could try to reflow all the solder joints on the board.Otherwise, try to see what voltages are delayed. Is the controller chip getting Vcc instantly? Are the primary side voltages coming up fast? Be extra careful of high voltage on the primary side of a switching supply when poking around - there's enough there to hurt/kill you. I would try to trace voltages through the schematic before simply randomly trying new parts.
Power supply Enermax identification component - Page 1
Forum section: electronics / repair

author: f114
author_rank: Newbie
timestamp: March 06, 2022, 03:15:30 am
content: My pc power supply had a short on the 3.3v line and also on the 12v line. When opening the power supply I checked some electrolytic capacitors in short and also a component that I could not identify.I would like someone to help me identify this component that has no number, just a red color band in the center.Thank you very much in advance

author: fzabkar
author_rank: Super Contributor
timestamp: March 06, 2022, 04:47:46 am
content: SA = Surge Arrestor (gas filled)?Something like this?https://int.rsdelivers.com/product/mitsubishi-materials/dsp-141n/mitsubishi-materials-dsp-140v-through-hole-surge/5258793https://docs.rs-online.com/33d3/0900766b813b84bc.pdfEdit:If the device is connected across a low voltage DC supply, then it may be zener diode or transient voltage suppressor.

author: f114
author_rank: Newbie
timestamp: March 06, 2022, 06:38:44 pm
content: Thank you for your collaboration, fzabkarAfter your post I looked for the component you suggested. And it really is a model RL102-201M 200v 1KA Gas Discharge Tube.
power supply Gossen 44T40R5 - Page 1
Forum section: electronics / repair

author: repairMatthias
author_rank: Newbie
timestamp: January 16, 2024, 10:19:57 am
content: I have a Gossen 44T40R5 built in 1973. Its 0-40V, 0-5A and still seems to work. There are 2 pcbs - regulator board A and may be a preregulator board B. I am searching for a schematic. There also had been a 44T20R10 with 0-20V 0-10A. Any available documentation like user manual, service manual, board layout, adjustment or repair hint for those devices would be helpful and is highly appreciated.

author: inse
author_rank: Super Contributor
timestamp: January 16, 2024, 02:26:30 pm
content: Years ago I also had a unit from that product range, the preregulator was kind of exotic, you could hear the current consumption of the load in the PFM/PDM.Everything was done with transistors, no ICs afair.Is it the same on yours?Unfortunately no documentation, possibly I swapped capacitors, gave it away later as it loaded the bench too much.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 16, 2024, 06:26:35 pm
content: from gossen you wont get far, they are very secretive for their service manualyou loose nothing to ask them ..... but to get high hopes sorrymaybe some user manual are floating around ...some threads elsewhere, some relations / similarities or nothttps://www.mikrocontroller.net/topic/416227#newhttps://bama.edebris.com/manuals/unigor/t4https://www.mikrocontroller.net/topic/500414https://www.mikrocontroller.net/topic/108881#newmain ic : maybe an lm723 or the mc1466or fully transistorized

author: Hamelec
author_rank: Regular Contributor
timestamp: January 16, 2024, 10:05:01 pm
content: see pdf, should be helpful.Pls let me know.... pdf removed

author: inse
author_rank: Super Contributor
timestamp: January 17, 2024, 03:16:25 am
content: This is the next generation already, from the 80‘s

author: Hamelec
author_rank: Regular Contributor
timestamp: January 17, 2024, 08:50:17 am
content: Quote from: inse on January 17, 2024, 03:16:25 amYes, I know. But the next generation could just be a facelift and the circuit could be more or less unchanged.Have to be checked..
Power supply HP PD18 DPS750RB A - ovp problems - Page 1
Forum section: electronics / repair

author: koszyk15
author_rank: Newbie
timestamp: December 10, 2022, 12:20:50 pm
content: Hello,I have n HP PD18 DPS750RB A , power supply and i adjust it for 13.8V.I have a problem with OVP,do any of you have a way to do this?
SMPS Power Supply in Denon DN-700-R - Page 1
Forum section: electronics / repair

author: gck303
author_rank: Newbie
timestamp: May 15, 2025, 03:27:35 pm
content: I have got a non-working solid state recorder (professional audio rack mount unit that that records a digitial audio file to either a SD/USB or network location).I have opened it up and done some basic diagnostics. Symptoms:- unit will not power on- will toggle between 'standby' and 'on', but it does not actually boot up and do anything- the power button is working. When you press i then parts theteh power supply get hot, likely too hot- two of small tiny transistors within the PSU are very hot (C3209 and A1281). They do not have heat sinks.The PSU boad has a few outputs. I will list out all of the connections. I can't find a service manual and someof them are not obvious.This set goes to the main processing board. These voltages all ready correctly and the top set turn on when powered up. These outputs all remain when the unit is in standby.+15V_D+12V_D+5_DGND_DGND_D+5V_SB (unswitched)+5V_SB (unswitched)P/S (connected to power switch)P_SENSThere are two sets of the same outputs that goes to the audio input/output boards. These read 0.7V and -8V.+16V_AGND_AGND_A-16V_AAUSTBYAttached are a couple of pictures. Highlighted are the hot (> 100C) components. BTW the shine on the board is freezespray.There are two transistors that are getting rather hot. Plus a couple of capacitors. They are two hot for my finger after about 5 seconds, or less.Seems like these components are the issue? Will it all work if those are replaced? Or, is the fault elsewhere?Many thanks, GeorgePS I am confident that the PSU fault is somewhere within the circuit attached. I managed to find a service manual for a similar device which happens to use the same PSU!

author: bostonman
author_rank: Super Contributor
timestamp: May 16, 2025, 02:08:51 am
content: If I understood correctly, you physically measured these voltages to be correct?You need to "shot gun" and trace. First step is trying to figure out all the connectors and the voltage/function. If possible, remove the connectors that may not be relevant to the unit powering (this is the step I take - I eliminate as much as possible until I hopefully narrow it down to a few connections and/or external boards).Next step I'd take would be to measure anything attached to a heat sink for a short. After, trace all the components from the ones that are hot to their connector voltage. It's a matter of analyzing, tracing, and then hypothesize.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: May 16, 2025, 04:47:25 am
content: I would suggest unplugging the +-16V connectors to check whether the problem is on the power board or something is loading the +-16V rails somewhere else.

author: bostonman
author_rank: Super Contributor
timestamp: May 16, 2025, 12:00:02 pm
content: Also, you could have a SMT capacitor that is resistive.
Power Supply Info - Page 1
Forum section: electronics / repair

author: C-47
author_rank: Regular Contributor
timestamp: July 17, 2022, 06:52:57 am
content: I acquired a Power Components, Gardena California power supply some years ago, now just getting setup to use it as it some useful outputs, anyone have any info on such or a schematic for such. Internet search reveals very little. Thanks, Alan.
Power Supply issue - Page 1
Forum section: electronics / repair

author: Crambone
author_rank: Frequent Contributor
timestamp: June 23, 2025, 08:31:42 pm
content: I have a CP2000 that let the smoke out on the power supply board Q805 (MJ2995) and popped the main 2amp fuse.I acquired a NOS MJ2955 and ordered a TIP32 and LM723 knowing I didn’t have any if they went bad?So I decided after I pulled the PS BOARD to install new electrolytic caps, new MJ2995, TIP32 (both), 1N5237’s, R813 & 814 (looked burnt).Put back together and something is not correct. I noticed when I put Q804 back in that even with insulators both behind the Cathode and mounting screw I’m seeing a ground of 23.5ohms. I did test all the parts with a PEAK DCA75 Pro & ESR70 gold along with a multimeter prior to installing. I then thought maybe I accidentally solder across 2 pads or traces but I looked and looked good and see nothing.So I lifted the new U800B (LM723) to see if that was an issue but 23.5ohm ground still there. So with all plugs going to PS Board disconnected (J801 & 802) I took some voltage readings on the J801 & 802 pins. On J802 with U800B (LM723) pulled I get the correct voltages.On J801 I’m seeing .5VDC but I’m assuming that U800B supplies that voltage. So I put U800B back in and turned on with my finger on R813 & 814 and HOT HOT HOT quickly it got so powered off.Pulled U800B and tested for grounds and I get grounds on pins 3,7 & 9.Power applied U800B still out I get 20VDC pins 11 & 12.I tried swapping the U800B & A and still same issue HOT HOT HOT R813 & 814?Attached a pic of schematic. Green highlight are parts I replaced and blue highlight parts I removed and tested.I took some voltage readings on Q800B turning On/ OFF letting cool down between.Pins2 28mVdc4 13.7Vdc5 4.2Vdc6 7.2Vdc8 15mVdc10 7.3Vdc11 19Vdc12 20Vdc13 10.3VdcAny suggestions?Thanks, Drew

author: CapLeaker
author_rank: Regular Contributor
timestamp: June 23, 2025, 10:56:01 pm
content: You gotta see 23.5 Ohm between GND and the collector of the TIP32A. There are two 47 Ohm resistors in parallel. That these are getting a bit toasty, I bet. Depends all on the watt size of the resistors.
Power Supply Lodestar LS1330 - Page 1
Forum section: electronics / repair

author: alecs
author_rank: Newbie
timestamp: November 22, 2023, 09:09:02 pm
content: Hi,I want to repair this power supply.The problem is when we adjust the voltage to values above 13V, the relay keeps switching and we can't adjust the voltage anymore, only for less voltage.Does anyone have its schematic?Thanks in advance for your attention.Best regards,Alex
Power supply "LONGWEI LW-3010D" failure - Page 1
Forum section: electronics / repair

author: IZ2KTE
author_rank: Newbie
timestamp: December 13, 2024, 09:56:07 pm
content: I am asking for advice regarding the "LONGWEI LW-3010D" power supply which has been having a problem with voltage regulation for a few days. Regardless of the setting of the current regulation potentiometer, by rotating the voltage potentiometer, from zero to eight volts the voltage respects the range of the multi-turn potentiometer, after eight volts the voltage, by rotating the "Voltage" potentiometer, begins to drop until it reaches zero, while the "CV" LED remains lit and with the rotation, almost at the end of the stroke the ventilation is activated. I have checked the efficiency of the potentiometers which are regular. I have measured the 12 V voltage on the "TP" and it is regular. The "CC" LED remains off, it is activated only when I bring the current regulation to zero, but this is regular.Thanks for your cooperation
Power supply nfs80-7602 from otdr hp 8147 - Page 1
Forum section: electronics / repair

author: Luzbel
author_rank: Newbie
timestamp: February 17, 2023, 10:21:27 pm
content: Hi everyone,The power supply burned the fuse, irf840 and diode CR2 but i can't see the code.Any one can help me with the code please.Ty

author: Luzbel
author_rank: Newbie
timestamp: February 17, 2023, 10:31:35 pm
content: Pics

author: R-1125F
author_rank: Regular Contributor
timestamp: February 19, 2023, 11:18:37 pm
content: Where was it in the circuit?

author: Chris56000
author_rank: Frequent Contributor
timestamp: February 21, 2023, 12:07:02 pm
content: Hi!BYV96D or BYV96E, 800V/1000V 1.5A fast recovery rectifier diodes, 1.5A rated, reverse recovery time 250ns for 600V/800V types, 300 ns for 1000V types!Chris Williams

author: Luzbel
author_rank: Newbie
timestamp: February 22, 2023, 04:59:41 pm
content: Ty soo much, the anode diode is connected to Drain mosfet, and catode is connected through R2 3k35w to the filter capacitor.I measured the transformer with a LCR motech 4080A, but a coil measures erratically if someone would be so kind as to tell me if it is an internal jumper or a bad coil.and this is the information of the rest in case it helps someone.Sorry for my English.
Power supply outputs random voltage - Page 1
Forum section: electronics / repair

author: uliano
author_rank: Regular Contributor
timestamp: September 28, 2022, 11:57:36 am
content: Suddenly (after maybe some year of NON use) this old PSU got crazyOften, but non always, more likely on channel 2, the voltage under load is less than programmed even if the drained current is far less than the preset limit.I have no idea where to start looking to investigate this problem.Some explicative pics.

author: wraper
author_rank: Unknown
timestamp: September 28, 2022, 12:12:22 pm
content: Your electronic load could be oscillating. Try adding say 1000uF cap to PSU output.

author: uliano
author_rank: Regular Contributor
timestamp: September 28, 2022, 01:37:16 pm
content: I didn't think it was the case as the problem showed up with a real (and very small) load, howeverWhat is worst is that it doesn't even need a load

author: Ice-Tea
author_rank: Super Contributor
timestamp: September 28, 2022, 02:44:00 pm
content: If memory serves (and that's by no means a guarantee), the polarity protection diode on the outputs is a weak point in these supplies. Wouldn't hurt to check. YMMV, obviously, but it doesn't hurt to check...
Power supply PWM - Page 1
Forum section: electronics / repair

author: Megael9
author_rank: Newbie
timestamp: November 26, 2021, 03:52:17 am
content: Hello every one,I’m currently working with a power supply which uses a microchip to generate the PWMs signals, however only one of the two signals is present at the microprocessor. My question is, can I use an inverter chip to generate the missing signal?This signal goes from the microchip to a driver chip part # ir4427 which drives the power supply Mosfets.Thank you

author: ambrosia heart
author_rank: Regular Contributor
timestamp: November 26, 2021, 12:42:18 pm
content: My question is, can I use an inverter chip to generate the missing signal?Don‘t do that. :phew:This PWM signal is controlled by the voltage output via photo-coupler and TL431/KA431. Detailed explanation see pm.

author: Megael9
author_rank: Newbie
timestamp: November 26, 2021, 03:15:45 pm
content: Hello and thank you for the quick reply.The manufacturer will not sell me the microchip for this power supply.Is there any suggestions for this problem.Thanks again

author: ambrosia heart
author_rank: Regular Contributor
timestamp: November 26, 2021, 11:16:19 pm
content: The manufacturer will not sell me the microchip for this power supply.Don‘t worry.Taobaocan help you. Find friends living inHong Kong or Taiwan to help you to buy one to fix thisstuff. They are at cheap price.I repair AV amps at components level. All components come from taobao.All work well. If I were you, I will choose 4-6RMB to buy.See photos.
Power Supply Repair of Adam Sub 7 Subwoofer - Page 1
Forum section: electronics / repair

author: Magnum
author_rank: Regular Contributor
timestamp: September 12, 2021, 11:03:11 am
content: Hello,I have a Adam Sub 7 Subwoofer where the Power Supply died.It has one board with the switching Power Supply and also the amplifier for the Sub on it.I don't know much about switching power supplies, but found a shorted diode on the secondary side and the controller chip (the big one with the heat sink) seems to have a problem. A resistor (120k), which is connected to it, gets quite hot (>70°C), and on one leg of this chip the solder melted.Unfortunately they removed all markings from that chip. So I don't know what it exactly is and where to get it.I isolated the power supply from the rest by removing the secondary diodes and injected +-20V to the board and everything works fine. My plan is now to disable the original PS and install another PS with +-20V. The question is, how many watts the new PS should have (when testing the board it needed less than 500mA to drive the sub at a quite high level) and what kind of PS I should use. As it is for audio, is there anything I should care about? Also I have not found a PS with +-20V, so I plan to use two 24V supplies, turn the output voltage down as much as possible (around 21V) and connect them together. Any ideas what I else should think about?Many thanks for your help. The sub is quite good and costs around EUR 400,- so I would like to make that (cheap) repair.Magnus

author: Audiorepair
author_rank: Frequent Contributor
timestamp: September 12, 2021, 01:48:28 pm
content: That black gunk all over the PCB is the type that goes conductive and corrosive, so you may want to remove any on the parts of the circuitry you are keeping.It's possibly what killed the PSU in the first place.

author: Magnum
author_rank: Regular Contributor
timestamp: September 15, 2021, 12:16:23 pm
content: Thank you for the info, I will remove that stuff.I am still wondering about the 20V power supplies I should use. I found two 12V voltage regulators on the board, they are rated with 700mA (positive) and 1,8A (negative). So I assume, that output ripple won't affect the quality too much, as it will be regulated again anyway. And 1,2A at 20V should be enough. Or am I wrong?
Power supply Rigol 1052E - Page 1
Forum section: electronics / repair

author: GGMM
author_rank: Frequent Contributor
timestamp: October 03, 2023, 07:43:29 am
content: Hello,Can someone inform me of the usefulness of the presence of a 50Htz or 60 Htz signal depending on the region, on the motherboard of the 1052E.see schématic of the power supply.Do you have the schematic about that on the motherboard?Is this some sort of watchdog from a voltage drop? Is there a link to a permanent reset command of the processor? (As if pressing permanent the reset button of a tower???)I ask you the question, because I still made many tests by pressing each time on a different button and necessarily I have each time a different menu. So it seems to go through the various loops of the program before it freezes.Thank you for your answers

author: Psi
author_rank: Super Contributor
timestamp: October 03, 2023, 07:47:58 am
content: It's used for the AC/Line trigger mode.When in AC/Line trigger mode you can display AC mains waveforms and it locks to the frequency.What else it might be used for as well i dunno.

author: 2N3055
author_rank: Super Contributor
timestamp: October 03, 2023, 01:10:46 pm
content: Quote from: Psi on October 03, 2023, 07:47:58 amLine trigger. That's it.

author: Zenith
author_rank: Frequent Contributor
timestamp: October 03, 2023, 01:21:16 pm
content: Quote from: Psi on October 03, 2023, 07:47:58 amThings based on mains frequency, such as 100 or 120 Hz ripple. Maybe mains hum pickup.It's a feature added to almost all scopes, but not something I've found particularly useful. I suppose it's easy and cheap to add, and it's expected.
[SOLVED] Power Supply swap between Tektronix B version and Non B version? - Page 1
Forum section: electronics / repair

author: charlyd
author_rank: Frequent Contributor
timestamp: March 31, 2022, 03:46:26 pm
content: hi i have this question about power supplies for the B version scopes. the number on the PSU is 2251-YE 05-02 where the non B-version have a a slightly different code 2251-25-4-001for the non B model i can find figure and codes in the service manual. but in the B version Service Manual nothing. the last thing i want is that there is a small difference and i blow boardsfor those who have broken psu look in the TLA71x series these are for sure equal to the non B version. even same part number according the SM from both TLA and Non-B scopesdoes someone know a tek code or order code for the B version series or did swap a psu between non-B version and B version tektronix 7000 series without any problems so they are 100% compatible.

author: alm
author_rank: Super Contributor
timestamp: April 01, 2022, 09:26:02 am
content: Maybe putting the model number (TLA71x) in the subject would give you a better chance of getting the attention of people familiar with them?

author: charlyd
author_rank: Frequent Contributor
timestamp: April 01, 2022, 05:36:03 pm
content: hi but i am not looking if the TLA71X psu fits in a non B versionscope. in both SM you find the same part number so yes these are interchangable.but now to the B version scope....Who can tell me about that supply.

author: charlyd
author_rank: Frequent Contributor
timestamp: April 02, 2022, 10:19:34 am
content: i did some looking arround on the web and here on the forum and @TiN did some swapping before he wrote. so he used a B version psu in a Non B verion scope i want to swap out opposite.as i think this will work too.

author: alm
author_rank: Super Contributor
timestamp: April 02, 2022, 10:56:21 am
content: You really should be more specific about which scope you're talking about, especially for a brand like Tektronix that has been making scopes for decades. Are you talking about a Tek465vs 465B?7912ADvs7192HD?TDS3000vs TDS3000B? Or specifically about the TDS7704B and CSA7404? It really helps to give people as much relevant information as you have, rather than them having to ask for it. I'd take TiN's word for it and guess you could swap power supplies between those two specific models, and likely models from the same series. But I would not generalize this to for example the TDS5000 vs TDS5000B. That would require checking the power supply (pinout, voltages and currents mostly) from both models, like TiN probably did.

author: charlyd
author_rank: Frequent Contributor
timestamp: April 03, 2022, 10:22:14 am
content: @alm, look at my first post last sentence, i am clearly pointing to the 7000 series for my feeling.i gues nobody really have the experience and the onces who have, just share the essentials ......................but i can confirm: that a psu of the non B model fits in a B model also. so it works both ways for people having psu problems and that means it also works to use a TLA71x psu in a tekscope 7000 series.
Power supply URMET Sch. 786/11 - Page 1
Forum section: electronics / repair

author: fant
author_rank: Contributor
timestamp: December 29, 2023, 11:07:59 am
content: A fiend of mine has three of such power supplies for the home entrance bell all the three not working, seems with the same failure.Opening it there is no sign of burning, the transformer is working and one output is working ( 15 Vac ), the other no, stable to 0 V.Anybody has the schematic diagram?Thank you in advanceMandi