hybridfree/eevblog-posts huggingface dataset:
[solved] Problem With horizontal positioning on Tektronix 2235 Oscilloscope - Page 1
Forum section: electronics / repair

author: solder_boy132
author_rank: Contributor
timestamp: December 23, 2020, 06:52:15 pm
content: I have a Tektronix 2235 oscilloscope. I replaced a broken BNC connecter on the scope, and then when i power it on, the trace is move to the left. I use the horizontal positioning knob to move it to the right, but it doesn't go all the way. Here is the link of the video where i show what is wrong:https://youtu.be/vFokxxRSsS4Read description for more details.

author: bob91343
author_rank: Super Contributor
timestamp: December 23, 2020, 07:54:26 pm
content: You need to measure some voltages in the horizontal circuit.

author: KevinA
author_rank: Regular Contributor
timestamp: December 23, 2020, 10:12:15 pm
content: Step 1, turn down the brightness; you will burn the screen.Measure the voltage on P9788 and P9778, and follow it back to the horizontal section to find the wrong voltage(s)

author: solder_boy132
author_rank: Contributor
timestamp: December 23, 2020, 11:31:47 pm
content: ok, and also, its the camera, its actually dim.

author: David Hess
author_rank: Super Contributor
timestamp: December 24, 2020, 12:05:11 am
content: Is the sweep shortened to about 1/2 or is the horizontal calibration off by a factor of 2? If so, then you may have knocked one of the leads off which go to the CRT horizontal pins.

author: solder_boy132
author_rank: Contributor
timestamp: December 24, 2020, 01:59:54 am
content: Having a bit of trouble removing the volts/div board. The problem also may be that its just old. It hasn't been repaired or serviced since 1989.

author: bob91343
author_rank: Super Contributor
timestamp: December 24, 2020, 04:34:41 am
content: 1989 is old? Not for most of us. I think my granddaughter was born around then. Most of my equipment is older than that.

author: tomthepom
author_rank: Newbie
timestamp: January 12, 2021, 03:06:30 am
content: I've received one of these scopes for Christmas but just got around to testing it today. Unfortunately, it has exactly the same issue yours has.Could this be some sort of issue with the calibration of the horizontal gain etc. (section 5-14 onwards in the service manual)? Sorry if this sounds stupid, I'm a complete noob when it comes to scopes and electronics in general really.Here's the link to the service manual I found as well in case its needed:https://www.palomararc.org/Manuals/Tektronix_2235_service_manual.pdf

author: solder_boy132
author_rank: Contributor
timestamp: January 15, 2021, 07:10:08 pm
content: Did you get it on ebay?

author: solder_boy132
author_rank: Contributor
timestamp: January 16, 2021, 12:35:55 am
content: Well fixed my scope. Turns out all i had to do was lend it to my brother, have him drop it while carrying it, and immediately giving it back to me! The horizontal works just fine now. I do not know why, but I'm guessing loose connections.

author: bob91343
author_rank: Super Contributor
timestamp: January 16, 2021, 06:52:22 pm
content: I am embarrassed to admit how many times I have repaired units that way. The hammer can be your best friend.
Problem with Korad KA6005P bench supply. - Page 1
Forum section: electronics / repair

author: danielrlee
author_rank: Newbie
timestamp: December 30, 2019, 03:44:06 pm
content: Hi allHaving been a lurker on EEVblog for many years, I've just registered a user account in order to ask for help with my Korad KA6005P bench supply.I have owned the above power supply for 13 months and up until now, it has performed flawlessly. Having just gone to use it again for the first time in a week or so, it appears to be having an issue outputting a stable voltage greater than 21V. Below 21V, everything appears to be okay, but with the output set to a higher value, the voltage quickly collapses to 21V where you can hear a relay switch. The voltage returns to the setpoint for the briefest of moments, then the voltage quickly collapses to 21V again and the cycle continues until the output is turned off manually.I do not come from an EE background, but I am confident that I could repair the power supply if I knew what was at fault.So, does anyone know what might be wrong?Thanks in advance for any assistance you are able to provide.Dan

author: danielrlee
author_rank: Newbie
timestamp: December 31, 2019, 12:06:18 pm
content: Having continued my search for information about the above fault, I stumbled across the following post detailing the same problem:https://www.eevblog.com/forum/repair/korad-ka3005p-power-supply-calibration/msg1129188/#msg1129188Following some pointers from a more experienced member, the fault was identified as a faulty relay K3. I'm not sure what they did to remedy the problem, but the user then posted that their power supply was now working perfectly.Having just given the K3 relay on my faulty unit a couple of strategically placed 'taps' (always worth a try with electro-mechanical devices), the power supply is now outputting a stable voltage. I don't expect the fix to last, but at least I now know which component is at fault for replacement. If (or when) the problem returns, I will update this thread with my experience in order to help others experiencing the same issue.Dan
Problem with reading VDC extech 520 - Page 1
Forum section: electronics / repair

author: lucidivo
author_rank: Newbie
timestamp: June 07, 2020, 01:14:34 pm
content: Hello guys,Well im new here and came along this page because I have a problem with my Extech 520. When I put it in VDC it reads automatically 370mv what should be near to 0. Now I find out if I put pressure on C12 the ma reading changes, tried with a other multimeter to look if I found a issue with it, as soon I put the pins over it the extech goes directly to 0mv.Does anyone know what to do?Ps. im new in those kind of things so I don't know what c12 isWith kind regards,lucidivo

author: lucidivo
author_rank: Newbie
timestamp: June 07, 2020, 01:15:33 pm
content: here is another picture with the whole multimeter on it

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 07, 2020, 07:06:28 pm
content: C12 is a ceramic capacitor but I don't think that component is the problem itself.Hopefully a bad solder somewhere, hard to find but if it comes to the worst you just go through the lot of them, that's what I'd do considering the quality of Extech products.If you're less lucky it could be a cut track or via, much harder to find because you can't use a shotgun approach.I owned an EX530 for a very brief period, it had bad contacts too, they turned out to be on the black resistor network on the side. Still considering the equipment I'd go through the lot, sell it fast once it's working and get a decent DMM.Here's the topic on the piece of rubbish I went over:https://www.eevblog.com/forum/repair/extech-ex530-multimeter-repair-attempt/msg2959806/

author: lucidivo
author_rank: Newbie
timestamp: June 08, 2020, 07:37:21 pm
content: okey thnx! I will go take a really in depth look then. hope to find it.
Problem with Samsung HT-DB120 - Page 1
Forum section: electronics / repair

author: etet
author_rank: Newbie
timestamp: May 01, 2024, 04:39:35 pm
content: Hi,this system has mainboard HT-DB120/THA25.Display working and also i can switch modes, but thereis no audio.I noticed that resistor R100 is heating up.I found wiring in attach, but there is diferences.1. In this wiring 1st pin of resistor is attached to diode bridge andsecond pin is attached to Collector of PQ5. On PCB is not the same.2. Resistor R100 is labaled as 10ohm, but it is 22ohm. Even colourcode (red, red, black, gold) show 22 ohm.3. Emitter of PQ5 must go to PIC4 (7812), but this also is not true.So, it seems that this is not right wiring that i found.I check also other 5-6 sites, but all is the same.Can somebody help?

author: FIXITNOW2003
author_rank: Regular Contributor
timestamp: May 02, 2024, 06:12:18 am
content: these do suffer with bad caps ,have you an ESR meter , C30/31 give various problems
Problem with Scotle - HR460 - Page 1
Forum section: electronics / repair

author: tony-tid
author_rank: Contributor
timestamp: October 21, 2022, 07:28:26 am
content: Hello there.I'm looking for help to fix myScotle - HR460.HMI: mcgsTP -TPC7062KDThe problem is that:After problem with emergency stop button - which was hardware problemIn haste to try to fix it, I try to restore previous settings and restart the system via HMI menu BUT when I do the "restore" procedure - accidentally delete all backup/project data/alarms and etc. including HMI software.And after that everything is in chinese.I attached the picturefrom internetabout Operation software that was installed originally.So my question is did someone else have fight with this and if they are - how they fix it?Download a software to connecto to the HMI but without success. I can upload *.zip file later.- I already try to find and contact the seller, but because the machine was bought a long time ago - the shop/email/skype is no loger in use/online.EDIT: Sorry if the topic is not for this section.

author: geomih
author_rank: Newbie
timestamp: December 12, 2023, 09:20:21 am
content: Hi - did you ever get to the bottom of this?I am in a similar situation, i purcahsed a Scotle HR460 used and the previous owner deleted most of the built in profiles (software is thankfully still there) and i am looking for a way to reset it without running into the issues you have.Thanks!

author: tony-tid
author_rank: Contributor
timestamp: December 12, 2023, 09:38:13 am
content: Hello geomih,Nope, the machine is not used since then and only collects dust.

author: geomih
author_rank: Newbie
timestamp: December 12, 2023, 04:26:26 pm
content: Really sorry to hear thatI would not have thought it, but after scouring the internet for a couple of weeks for a copy of the software I could not find anything; can't understand how after selling so many of these machines the company simple packed up and left nothing in the way of support. ACHI which seems to be the successor also seems to be on their way out because the website hasn't been updated since 2018 and is almost completely broken. I will try to email or get in touch with them, but i don't have high hopes.These are the details i found on their website - if you want you might give it a go as well0086-755-83692414Ms Sunnyeasybga@gmail.com0086-755-89378931Sunny-scotleFailing that I am guessing its either cloning a working machine's NAND or replacing the whole MCGS control system with something like a PC410 Temperature Controller, but even thinking about it makes my head hurt.

author: tony-tid
author_rank: Contributor
timestamp: December 13, 2023, 06:22:02 am
content: Quote from: geomih on December 12, 2023, 04:26:26 pmI may give it a try.Thanks!
Problem with the backlight of the CME dt-9939 multimeter display - Page 1
Forum section: electronics / repair

author: krysjaz14
author_rank: Newbie
timestamp: April 19, 2021, 04:09:23 pm
content: HiAt the outset, I apologize for the language. I am an electronics beginner, I recently bought a used CEM DT-9939 (version DT-9939-9) multimeter and I have a problem with the display backlight and the low battery icon is still displayed despite the new battery. The voltage on the LED comes to 4.4  when the backlight is turned on. I replaced the transistors but the problem is still there. As I look, you can see it on a different layer as it would be powered directly from the battery plus but I'm not sure. In addition, this battery level constantly signals discharge.
Problema en el inicio del analizador de espectro R&S FSP 3 Ref. 1093.4495.03 - Page 1
Forum section: electronics / repair

author: pepepontevedra
author_rank: Newbie
timestamp: February 13, 2022, 12:54:23 pm
content: ¡Buenos días a toda la comunidad!Este es mi primer mensaje y para ello me presento.Me llamo Pepe, vivo cerca de Santiago de Compostela, tengo 60 años y llevo toda la vida dedicado al mantenimiento de centros emisores de FM y OM de esos de muchos KW.Me recomendaron este foro al consultar a un compañero sobre un problema que tengo con un analizador de espectro R&S FSP 3 Ref. 1093.4495.03. para lo cual necesito ayuda ya que este medidor está fuera de servicio por parte de R&S.El medidor funcionaba bien hasta que hace unos días.En el arranque cuando carga el software da dos opciones: 1 Cargar software analizador o 2 Hacer software backup.El arranque es automático en uno de los dos menús trascurridos unos segundos.Al arrancar en modo Backup hizo una serie de remplazo de ficheros y al terminar se pasó directamente a arranque en modo analizador.El problema es que al llegar al punto donde carga los archivos de Windows NT sale un error que dice: \WINNT\SYSTEM32\CONFIG\SYSTEMHardware Profile/Last Known Good menuLuego me pide un disco de arranque que no tengo ni se donde conseguirlo.Tampoco tengo claro como hacer para que vaya al disco de arranque ya que no hay forma de entrar en el menú de configuración de la BIOS.Si alguien puede aportar ideas le estaré eternamente agradecido.
Problems with Multimeter Vichy VC97 - Page 1
Forum section: electronics / repair

author: nForce
author_rank: Frequent Contributor
timestamp: October 19, 2019, 03:21:15 pm
content: When I was testing the multimeter for resistance and continuity, I notice that most of the time the multimeter does not read the value of the resistance. Also for continuity, it does not beep. Occasionally it does work, but not most of the time. When not working I get ".0L" reading. I don't understand why? I reset the meter a few times, but also the same problem.Did anyone had any similar problems?

author: PKTKS
author_rank: Super Contributor
timestamp: October 19, 2019, 04:01:30 pm
content: NoThey have fairly good qualityBut considering overall cost of similar product class ...- Check the probes - several times they are bad.they are mostly got from other supplier in chain- Open the DMM and check the solders of the probes on pcbseveral times they are bad either. Usually they are hand madeon a not very good production line- Perform overall visual inspection - cold or bad joints do happen a lotAll very easy to fix.. and very common.Mostly you will need another DMM as wellLast but not least the ROTARY POSITIONAL KEY..very frequently they have some issues.. more or less fixable.Paul

author: mzacharias
author_rank: Frequent Contributor
timestamp: October 20, 2019, 12:39:55 am
content: Bad test leads?
Problems with the AC setting of the multimeter - Page 1
Forum section: electronics / repair

author: Wu
author_rank: Newbie
timestamp: October 10, 2025, 03:42:20 am
content: I have a multimeter at hand, which is made by Taiwan Escort and model 3146A. The AC voltage setting of 750V has a problem.When I input 100V AC voltage to this device, it shows 750V. When I input 50V, it shows around 370V. This seems to be a common problem, but I'm not quite sure about it. Could it be that the resistor is broken?Are there any better measurement methods?

author: DavidAlberto
author_rank: Contributor
timestamp: October 10, 2025, 07:02:46 am
content: Hello, what condition is the multimeter in? Could it be contaminated or deteriorated? If so, I recommend cleaning the selector switch unit and, since you have it disassembled, visually checking the condition of the electronic components for possible assembly failures or damage.In my case, I regularly use the Fluke 87V and I used the Hioki MR8870-20 oscilloscope model for a while, both with great results. However, the Fluke is a bit more economical and works very well.
PROBOX2 EX+ - Page 1
Forum section: electronics / repair

author: htrv
author_rank: Newbie
timestamp: October 09, 2025, 06:03:43 am
content: Hey,I dug out an old PROBOX2 EX Plus. When I plug in the power, it shows the PROBOX logo screen and then keeps restarting itself.I assume the memory might be corrupted and needs to be reflashed, but unfortunately the PROBOX website is down and every link I found to firmware images and burning tools is broken.If anyone has working links to the IMG file and the burning software, I’d really appreciate it.Also, I’m not 100% sure this is just a firmware issue. When I connect the OTG port to my computer and pulling the reset botton on powerup, Windows keeps detecting new hardware and then disconnecting it every few seconds. Does anyone happen to have the circuit/schematics for this box?Thanks!

author: Kean
author_rank: Unknown
timestamp: October 09, 2025, 08:55:02 am
content: How hard would it have been to mention this is an Android TV box so people didn't have to do their own search?This problem sounds like a power supply issue to me. Have you tried a different external PSU?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 09, 2025, 09:39:54 am
content: look on XDA forums ...this is an old box, even recovered it was android 5 or 6 based.... wayyyy outdated, many apps wont work anymore on it
Proceed AVP  - Page 1
Forum section: electronics / repair

author: mario_nks
author_rank: Contributor
timestamp: June 18, 2025, 05:43:10 am
content: Hello at all,I have an Proceed audio video preamplifier with problem.After switching it on, it just stays on the display with "INTIALIZING," and I can press the buttons, but nothing happens.The Standby button doesn't respond either. I measuered all Voltages an Clocks in the Unit. That seems to be OK.I can measure the signal from the keypad to the "processor" as soon as a button is pressed, but nothing else happens.Has anyone here already repaired a part like this and can perhaps give me some tips?Best regardsMario

author: m k
author_rank: Super Contributor
timestamp: June 22, 2025, 07:26:57 pm
content: Seems that one part is not communicating.Maybe there are some fuses in unusual places.
Prodigit 2000MU energy meter repair - resistor value - Page 1
Forum section: electronics / repair

author: kamal
author_rank: Newbie
timestamp: January 01, 2025, 12:11:54 pm
content: One of the resistors of this Prodigit 2000MU energy meter has burned. Please see the attachment. I replaced it with a 10k but it still gets hot.It appears to be a 2 or 3W resistor. Can someone let me know the correct value of it?

author: HighVoltage
author_rank: Super Contributor
timestamp: January 01, 2025, 12:18:53 pm
content: Well, there is a good possibility that something else is wrong.You need to check the circuity after this resistor to find out what is pulling this current wrongly.

author: kamal
author_rank: Newbie
timestamp: January 01, 2025, 12:31:18 pm
content: Quote from: HighVoltage on January 01, 2025, 12:18:53 pmThanks for the suggestion. I'll keep a tab on that.At the moment my guess is that for some reason the resistance got increased and hence the larger voltage drop caused it to heat up and finally failed. I wonder if the value is like 100 ohms. 10k won't be a match then and explains why it continues to heat up. Before trying with other resistance values, I thought of seeking help.

author: kamal
author_rank: Newbie
timestamp: January 07, 2025, 06:23:11 am
content: After looking at the capacitive power supply circuit, I determined that a 100 ohms wouldn't cause a problem so replaced the resistor with a 100 ohms 3W one. No more abnormal heating of the resistor, the device is working well now.
prodigit 3320.Need repair or calibration. Need a scheme. - Page 1
Forum section: electronics / repair

author: Alex06
author_rank: Contributor
timestamp: November 05, 2019, 08:16:59 pm
content: Hello. This is still a newcomer. I decided to ask you for help, as I myself couldn’t do anything yet.I have an electronic load Akip-1301A 60V / 30A(foreign analog of Prodigit 3320 60V / 30A) copy of 100%.The malfunction lies in the inaccuracy of the readings that I submit to her voltmeter.From 0 to 19 V is not resp., But from 20 to 60 V goes.There are several tuning resistors, but so far they do not help.On the Internet I was looking for a service manual or circuit, I did not find anything.Maybe someone will help with the scheme or tell me where to go next.

author: wraper
author_rank: Unknown
timestamp: November 05, 2019, 08:28:27 pm
content: Пост на всём кроме английского могут удалить, так что советую писать на нём. Тем более что большинство местного народа не будет заморачиваться переводить. И это не копия, а он и есть. Весь акип это тупо смена шильдика.

author: dom0
author_rank: Super Contributor
timestamp: November 06, 2019, 09:11:13 pm
content: The auto-ranging of the meter may be broken.

author: Alex06
author_rank: Contributor
timestamp: November 07, 2019, 05:55:00 am
content: One person suggested that it should be calibrated for accuracy. In the service manual it is. But on the Internet, I did not find it.

author: wraper
author_rank: Unknown
timestamp: November 07, 2019, 02:19:28 pm
content: QuoteDo you mean up to 19V it does not work at all or you cannot adjust? If inaccuracy, how much. It could be a fault, not calibration problem.

author: Alex06
author_rank: Contributor
timestamp: November 07, 2019, 04:19:16 pm
content: measured the reading

author: dom0
author_rank: Super Contributor
timestamp: November 07, 2019, 08:24:59 pm
content: So it should be accurate to +- 0.05 % + 2 counts, yours is up to 0.2 V out (15 V / 15.2 V), +1.3 % error.Range switching is indeed done at 20 V. So the lower range needs adjustment, preferably to an reliable, accurate multimeter. Handheld 4 1/2 digit would probably be ok. There is probably one trimmer or 20-turn pot for each range.

author: Alex06
author_rank: Contributor
timestamp: November 08, 2019, 10:33:58 am
content: I twisted some resistance, and put in place. They did not help. Only the general adjustment range was found

author: danilnik
author_rank: Newbie
timestamp: February 11, 2022, 06:19:30 am
content: Hello everyone. Can I bring this topic up? Maybe someone got a service manual or calibration method for this device?
programming PASMO s318c ice cream machine - Page 1
Forum section: electronics / repair

author: diag7919
author_rank: Contributor
timestamp: July 17, 2020, 09:13:55 am
content: Here's a long shot but interesting repair.. This machine is about 5 years old, initially, I thought it was an electronics issue but now I believe its a programming issue.. . There's no information online and OEM / importer refuse to supply the information.. When the machine initially starts (defrosted/no load on stirrer) the viscosity reading (ice cream thickness) starts at zero and increases slowly until the set viscosity is reached whereby the freezer and paddle motor turn off and machine ready to use. Except, for whatever reason, this machine now starts at a higher level.. Does anyone in the EEVblog community know how to program one if these units.. They might be branded as Sumstar.. Cheers..
programming some old chips - Page 1
Forum section: electronics / repair

author: davest
author_rank: Newbie
timestamp: January 17, 2023, 08:05:05 am
content: I am looking for programmers for the following devices:M30627FHPGPEPM7064SLC84-10NP87C51MBA/02MC908GT8CBEC1937-01M308B8SGPAny suggestions?

author: retiredfeline
author_rank: Frequent Contributor
timestamp: January 17, 2023, 08:39:51 am
content: P87C51MBA/02Possibly of the 8051 family. If no quartz window then OTP and you're out of luck, but you might be able to replace it with flash memory 8051 model.

author: Circlotron
author_rank: Super Contributor
timestamp: January 17, 2023, 10:43:36 am
content: Quote from: davest on January 17, 2023, 08:05:05 amGT8A is listed in the Device Selection for this programmer. I've used it on several thousand S08PA, S08PT and some S08FL micros. Works great and very inexpensive. Linux version available too. Use the free software from sourceforge, not the supplied CD. More up to date.https://www.ebay.com.au/itm/304105857508https://sourceforge.net/projects/usbdm/
programming with TL866 - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: January 29, 2021, 02:24:22 pm
content: Good morning all! Today, I am in programming, and I am trying to use TL866 programmer and adapter (PLCC44 / DIP40) to retrieve the program from the integrated circuit: EE87C511 (PLCC44), to put it in: AT89C51LR (PLLC44) , and the programmer software tells me: overload or short circuit every time I try programming !? (the circuit is however completely new and has not been soldered, and I have respected the meaning with the point on the adapter). Reading from EE87C511 works well, and so does AT89C51LR. My question is therefore the following: is the correspondence between the 2 circuits good?

author: coromonadalix
author_rank: Super Contributor
timestamp: January 29, 2021, 03:27:11 pm
content: is your test socket came with the tl866 or its made for another programmer ?? some tests socket are universals and some are not, some tl866 have an eeprom on the tests socket to tell the tl866 software you're using are the genuines one for itcpu orientation in the socket ?Bad insertions ?for a 44 pins plcc socket, you have to put the test socket at the right place in the tl866 ??Normally this error mean the test socket doesn't have the needed pinout to test the ic put in it hence the overload error, something gives a short in the programmerYou have here a huge thread for the tl866 a search will help you find it.https://www.eevblog.com/forum/blog/eevblog-411-minipro-tl866-universal-programmer-review/

author: DeepLink
author_rank: Regular Contributor
timestamp: February 02, 2021, 07:22:13 am
content: The PLCC44 socket's for 27Cxxxx EPROM's and for 80C51 does not have the same pinoutYou need a PLCC 44 socket specific for 80C51See these (pinouts a bit down on the pages)http://www.mqp.com/ad44.htmhttp://www.mqp.com/ad45.htm

author: lionelkjh
author_rank: Frequent Contributor
timestamp: February 07, 2021, 09:57:21 am
content: Hello, and thank you for this info. To do even better, I am going to take a new 87C51 and program it, I am sure I have no more error messages in both reading and writing! Cdt
Proper replacement battery for this - Page 1
Forum section: electronics / repair

author: alank2
author_rank: Super Contributor
timestamp: October 15, 2022, 05:14:40 pm
content: I'm trying to fix an old Toshiba notebook computer - T4800CT. Its hardware manual mentions the RTC battery as this:RTC battery, Lithium-Vanadium, 3.0 V, 50 mAhOther parts of the manual talk about the RTC battery being a rechargeable and lasting 30 days or so if not in use.IS a ML2032 a replacement for this? Something else? I've noticed a lot of 2032 sized rechargeables talking about 3.6V and not 3V which is what is needed.

author: wasedadoc
author_rank: Super Contributor
timestamp: October 15, 2022, 05:26:25 pm
content: Panasonic VL-2330.eghttps://uk.rs-online.com/web/p/button-rechargeable-batteries/0407899
ProsKit 331 Heater Replacement - Page 1
Forum section: electronics / repair

author: Ricks_Radio
author_rank: Contributor
timestamp: March 14, 2025, 10:46:54 pm
content: I have a 110-120 VAC version of the ProsKit 331 solder sucker. It works well BUT I've heard that the heater elements are short lived and having a spare heater element might be wise. Without access to a schematic, I have been unable to determine the voltage rating on my heater tube.My model 331 operates on the standard North American 120 VAC. The heater elements that I have found for sale on-line either do not specify a voltage OR state they are for 220 VAC.Does anyone know what voltage is sent to the heater? Does anyone have the pin-out for the 7-pin connector?Thanks,Rick

author: thm_w
author_rank: Super Contributor
timestamp: March 15, 2025, 01:09:14 am
content: https://www.aliexpress.us/item/2251832758326482.htmlhttps://www.eevblog.com/forum/repair/proskit-ss-331-soldering-gun-replacement-heater/https://canada.newark.com/proskit-industries/5ss-331-h/heating-element-for-desoldering/dp/68Y6658https://www.gmelectronic.com/v/1504694/proskit-5ss-331-h-heater-for-desoldering-station-gun-ss-331bI think its a 24V heater, so 110/220 would be the same. But double check that before ordering anything.Visually appears similar to ZD917, but there is a comment here saying its different size:https://usa.banggood.com/ProsKit-SS-331H-Electric-Solder-Sucker-Desoldering-Device-Anti-static-High-Power-Strong-Suction-Desoldering-Pump-for-PCB-Circuit-Board-Repair-reviews-p1375060.html
Proskit MT-3109 AC/DC Digital Clamp Multimeter not displaying anything - Page 1
Forum section: electronics / repair

author: zillah
author_rank: Contributor
timestamp: September 21, 2025, 01:01:45 am
content: Dear ExpertsI have got very rarely used Proskit MT-3109 AC/DC Digital Clamp Multimeter, I needed to use it recently I realized nothing display in the screen I thought we need to replace the 3xAAA batteriesBut still nothing display in the screenhttps://pacific-electronics.com/pro-skit-mt-3109-ac-dc-digital-clamp-multimeteri was trying to see if any fuse blown up but I need to remove the back cover gently but not to pry it :QuoteBut I am struggling to lift it off completely ,,,,,,,,,,,,,top par I can lift it off but not bottom oneThx

author: Swake
author_rank: Frequent Contributor
timestamp: September 23, 2025, 08:49:11 am
content: That sounds like an AI generated response. Be conscience these things have never touched anything in real life....Either the case is glued shut (but then it would be unlikely to have screws) or there is some tab or something that keeps it from popping open. Or you forgot a screw, hidden under a sticker or something.

author: zillah
author_rank: Contributor
timestamp: September 24, 2025, 02:48:19 am
content: Thx Swake ,,,,yes it was AI and there is a screw under QC sticker that was holding the back coverNow issue I couldn't located any burnt fuse as I haven't see any fuse to be checked ,,,,,but still clamp multimeter is not working

author: floobydust
author_rank: Super Contributor
timestamp: September 24, 2025, 03:37:00 am
content: cross-posted with pictures that we don't gethttps://forum.allaboutcircuits.com/threads/proskit-mt-3109-ac-dc-digital-clamp-multimeter-not-displaying-anything.208142/
Proskit SS-989B Hot Air Blowing Station, CARD FAILURE. - Page 1
Forum section: electronics / repair

author: elektronikartamircisi
author_rank: Newbie
timestamp: July 19, 2025, 09:35:46 am
content: Hello, I'm new to your family. First of all, I wish everyone the best.This electronic board belongs to the "Proskit SS-989B" product.The zener diode I marked in the close-up image has blown, and I can't find its values anywhere.The more information we can gather about the board, the better.Finding the circuit diagram is the most important thing, but I can't find it anywhere.Many thanks in advance to anyone who can help me.

author: klammerj
author_rank: Newbie
timestamp: July 19, 2025, 09:46:56 am
content: 12V ? (going by the writing on the relais)

author: elektronikartamircisi
author_rank: Newbie
timestamp: July 19, 2025, 12:51:42 pm
content: Thanks. I tried 12v but it blew again, I'm looking for a short circuit in the circuit now.

author: IanJ
author_rank: Unknown
timestamp: July 19, 2025, 01:35:45 pm
content: Some quick observations from the photo:Check to see the electrolytics aren't bulging.Discoloured flux in and around some of the components, might be heat related.Lots of flux residue all over the board, it would be worth a good clean.Check the tantalums, prone to dead shorts.A 6.5digit multimeter in ohms mode will track down the dead short pretty quick.Ian.

author: elektronikartamircisi
author_rank: Newbie
timestamp: July 21, 2025, 08:38:41 am
content: Thank you very much.Despite measuring repeatedly, I couldn't find a short circuit.But the serial light is still on.Since this photo was taken immediately after the soldering process, there were some residue.But the residue was removed after the photo was taken.I'm trying to create the circuit diagram now.
Protection circuit, blown FET. But weird low side FET circuit? - Page 1
Forum section: electronics / repair

author: sw_guy
author_rank: Regular Contributor
timestamp: March 30, 2024, 10:18:04 pm
content: The circuit is a protection circuit for a device which is not a charger. One fet is blown and according to package pins I assume the order of Source and Drive pins.The M1 FET looks like a standard low-side FET protection. However, the one that is blown, does not make sense to me. This kind of arrangement is often seen in battery protection circuits. Which this is not.Based on the Gate circuit, this look like a N-type FET. If it is the same as M1, it does pretty much nothing since the internal diode lets current pass the fet (?)

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 30, 2024, 11:29:30 pm
content: M2 looks like a reverse polarity protection circuit. Instead of a diode, which has a 0.7V drop, they use a MOSFET which has a much lower voltage drop due to it's low RDS(on).

author: sw_guy
author_rank: Regular Contributor
timestamp: March 31, 2024, 05:50:57 am
content: Right, thanks. Now when you say this, reverse protection it must be. And M2 "must" be the same as the M1.

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 31, 2024, 11:07:54 am
content: Yep M2 is for reverse polarity protection, M1 does some sort of soft turn-on.

author: inse
author_rank: Super Contributor
timestamp: March 31, 2024, 11:51:30 am
content: But not with this voltage divider value…and what’s the 50mR good for?

author: sw_guy
author_rank: Regular Contributor
timestamp: March 31, 2024, 08:13:02 pm
content: R3 is clearly higher than 8k2 which I measured in-circuit. >18VDC there is 14.7V over the D1. R1 is 124k and R4 is 3 x 124kThere are several unpopulated components on the board around 50mR resistor. I think there is an option to have over-current protection. I did not analyzed that further.
Protek 3040t - Page 1
Forum section: electronics / repair

author: kolonelkadat
author_rank: Regular Contributor
timestamp: August 10, 2022, 12:17:43 pm
content: Anyone happen to have or know where I can get a schematic and or manual for a Protek 3040t Triple Output Power Supply?

author: m k
author_rank: Super Contributor
timestamp: August 17, 2022, 07:26:59 pm
content: The face of it seems to be pretty generic.Maybe there are some other names with better support.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 18, 2022, 10:19:28 am
content: I would try to find something in the Mastech brand ??
Request for Protek 3305L Service Manual / Schematics - Page 1
Forum section: electronics / repair

author: rfengg
author_rank: Regular Contributor
timestamp: April 07, 2022, 02:02:25 pm
content: May I ask for help in locating the Service Manual / Schematics of the Protek 3305L power supply?I have looked at the usual places but in vain , so any pointers to even a similar model would be most helpful.TIA.
Protek 506 resistance measurement confusion - Page 1
Forum section: electronics / repair

author: W1BCC
author_rank: Newbie
timestamp: February 26, 2021, 02:55:09 pm
content: Protek 506 - used, but new to me. Nice rubber case and leads.My Fluke 175 says a 10k resistor is 10k.Using same leads, the 506 says 11.8k. Shorting = 1.8kApplied a thorough squint to the manual. No calibration or reset options noted. Even swapped out the fuses,What happened?Thanks,--Brad W1BCC

author: retiredcaps
author_rank: Super Contributor
timestamp: February 26, 2021, 08:36:41 pm
content: I suggest checking the input protection starting with the MOVs and PTCs. A good MOV should measure 0L ohm using Fluke 175. A good PTC should measure between 500 ohm and 1500 ohm (an estimate on my part). Both can be done in circuit.

author: srb1954
author_rank: Super Contributor
timestamp: February 26, 2021, 08:51:28 pm
content: Quote from: W1BCC on February 26, 2021, 02:55:09 pmDoes the meter give correct readings on the volts and current ranges?Check the voltage drop across the meter when measuring current. Does it comply with the burden voltage specified for the meter?Try a different set of test leads.Check and clean the input jacks.

author: W1BCC
author_rank: Newbie
timestamp: March 03, 2021, 04:02:58 pm
content: Yes, tried swapping leads. Also a little DeoxIt.Appears to measures resistance accurately, just with an additional 1.7k.Otherwise, it seems to function properly.Thanks for all the suggestions,--Brad W1BCC
Protek 506 Voltage Measurement Problem - Page 1
Forum section: electronics / repair

author: mustafayilmaz
author_rank: Contributor
timestamp: November 07, 2023, 07:04:09 am
content: Hello,I don't use Protek 506 very often. There was no overload situation on the device.When I wanted to take a measurement the other day, I realized that the measurement was incorrect. I corrected the commutator and tried again. It did not measure AC voltage. It appeared as 0.000V.I disassembled the device and cleaned the comitator legs. It gave accurate measurements for a short while. Afterwards, I see extremely volatile values. The voltage, which should normally be 10.5, appears to vary around 11~13 over time. I think it changes slightly when the device shakes.It shows values around 40~45 C in the temp level.At the mV level, when the probes are short-circuited, it is 0mV. When the probes are open-circuited, the voltage increases within a few seconds and appears as OL.It makes incorrect measurements at Temp, ACV, DCV and mV levels.In addition, the diode stage is working properly, but when the probes are idle, they are close to the required values, but the voltage value on the screen is not stable.I did not see any defective material. But ZD15 shows 0.5~0.6V diode voltage in both directions.

author: mustafayilmaz
author_rank: Contributor
timestamp: November 09, 2023, 10:47:01 am
content: The measuring device now makes accurate measurements. I think there was a lack of contact somewhere.The problem at this mV level still persists. Will it be fixed if I change the reference voltage?When the probes are idle, a voltage of around 300-400 mV occurs. It's like a capacitor charging and eventually the screen says OL.
Protek 6510 Oscilloscope User and Service manuals (Attempt #2) - Page 1
Forum section: electronics / repair

author: EvgenyG
author_rank: Regular Contributor
timestamp: February 13, 2023, 04:44:59 am
content: Hi All,Does anybody have a user and/or service manual for Protek 6510 Oscilloscope? Also known as Hung Chang 6510 - 100Mhz Oscilloscope.It is a pretty nice old school analog scope. It had a fat trace fault that I've managed to fix. Would love to calibrate it now, because it is a bit off.I've searched the Internet but I could only find user/service manuals for 6502/04/06 scopes but those are completely different inside. Both horizontal and vertical units have completely different layout. I also reached out to Protek via email. Surprisingly, they did come back to me but said that the scope is too old and they have no documentation for it.

author: fzabkar
author_rank: Super Contributor
timestamp: February 13, 2023, 04:57:33 am
content: Mouser used to be an Authorized Distributor. Perhaps they have a user manual?https://www.mouser.com/datasheet/2/333/04_6510-6780.pdf

author: EvgenyG
author_rank: Regular Contributor
timestamp: February 13, 2023, 05:17:11 am
content: I've just sent a support request to Mouser. Little hope but will see. I was thinking to call scope calibration companies and see if they could calibrate it? If they do, they must have a service manual. Any thoughts on this?

author: fzabkar
author_rank: Super Contributor
timestamp: February 13, 2023, 07:11:55 am
content: I've never had anything calibrated, so I have no idea.BTW, I did try Protek's old web sites at the Wayback Machine, but they only have the same datasheet.https://web.archive.org/web/20230000000000*/www.protektest.com/
Prova AVM-07 Anemometer Wind Turbine and cable assembly needed. - Page 1
Forum section: electronics / repair

author: Paceguy
author_rank: Regular Contributor
timestamp: April 30, 2024, 11:48:25 am
content: Someone gave me this Prova AVM-07 Anemometer unit but sadly, it's missing the wind turbine and cable assembly which was cut off. Does anyone happen to have a parted out unit and would be willing to sell me what is missing on mine?
Ps-305d power supply  - Page 1
Forum section: electronics / repair

author: Abdulla544
author_rank: Newbie
timestamp: May 26, 2021, 09:45:11 am
content: HiMy ps-305d 30v 5A power supply '' FINE'' range didn't work properly so I opened it up and I just figured out that it was a 1k dual-line pot that u can adjust the voltage at about 0 to 2.5v the button of it didn't work I didn't have 1k dual-line pot instead I attach 50k then my power supply showed short-circuit on the output display nothing wrong happened like smoke or something but I no longer have the ability to control the voltage I just can control the amp section and by the way, the output polarity protection diode didn't short and I also tested the output ohmage it showed 850ohm not short-circuited.Can u please help me how to fix it?

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: May 26, 2021, 10:17:27 am
content: You already answered your own question.The fine adjustment is a potentiometer that is in series with the coarse adjustment. You replaced that with a 50k instead of 1k, so that can't work.Replace the 50k pot with two fixed 470 Ohm resistors from wiper contact to upper/lower pin and see if the coarse adjustment works again.

author: aa0cn
author_rank: Newbie
timestamp: June 22, 2021, 07:14:25 pm
content: I did a finals repair on my PS-305D, so not the same issue, but you can find schematics for this unit here:https://aa0cn.neocities.org/ps-305dm.htmlOr from PierAsia on his site here:https://www.pieraisa.it/php/myHwProjects.htmlHope this is helpful!
PS 305D  : Voltage is not going to its Max - Page 1
Forum section: electronics / repair

author: Jaival
author_rank: Newbie
timestamp: April 08, 2019, 09:18:56 am
content: HiHaving PS 305D and Previously Voltage is controlled by "Fine" and "Coarse" Knob of Supply and able to vary output from 0 to 30V .But now there is hardly any effect of "Fine" Knob . And with "Main/Coarse" Knob able to vary Volt till 12 V and not reaching to it max value .But With Current "Fine" and "Main/Coarse" Knob able to reach to 5A .Checked the following :1) Transformer output seems fineTransformer output AC1 to AC2 ~ 7vTransformer output AC1 to AC3 ~ 22vTransformer output AC1 to AC4 ~ 38v2) Both Relay is working (Manually checked)3) "Coarse/Main" And "Fine" Knob of Volt seems fine as when rotating Voltage is varying @ out (Middle point) of POT.4) Reference O/P at LM324 is -10.76 V and @ TL431A is 3.2VAnd having the same schematic and PCB which is present in below Thread .https://www.eevblog.com/forum/repair/new-power-supply-ps305d-not-regulating-and-running-over-voltage-and-current/So please can i have any suggestion what can be issue ?Regards+Jaival

author: syedhussain_alishah
author_rank: Newbie
timestamp: October 09, 2019, 07:20:52 pm
content: did you find the problem.?
PS2 PRT error on yamaha receiver - Page 1
Forum section: electronics / repair

author: Gersti24
author_rank: Newbie
timestamp: January 09, 2024, 03:43:58 pm
content: Need help on a receiver I got During startup it goes into protectionerror is PS2 PRT 084model is RX-V6Aanyone have experience with this symptom on this generation of receivers. or can share with me the diagramsthank you!
PS2 Replacement Ribbon Cable - Page 1
Forum section: electronics / repair

author: pharaoh3
author_rank: Contributor
timestamp: February 04, 2023, 03:49:07 pm
content: I have a Fat PS2 30001 and the ribbon cable for the power button is brokenI am trying to find a replacement, and I think I have found a suitable one on Digi-Key. However I have never ordered a ribbon cable before, so I am looking for some advice.Digi-Key Product #: 0151670763-NDThere are 7 and the width of the cable is 8mm. Thus the pitch is 1.Length of the exposed ends is 4mm. However the backers are of different length on the OEM cable. Please see the attached picture.The original cable is about 9" long, but I went with a 10" cable for ease of installation.Would this cable work?

author: m k
author_rank: Super Contributor
timestamp: February 07, 2023, 05:57:11 pm
content: Mechanicals are not a problem, you can always add some missing stuff.Only problems are power and stiffness.If it's only a button operation then power is irrelevant.If there are no too sharp corners then stiffness is also pretty irrelevant.Are different cable colors a camera effect?If not then what they possible are?
PS2 Slim Not Powering On - Page 1
Forum section: electronics / repair

author: pharaoh3
author_rank: Contributor
timestamp: February 09, 2023, 07:37:46 pm
content: I have a Silver PS2 Slim SCPH-79001 which has a different motherboard than most PS2 slims that I come across. When I got this PS2 it was having issues reading discs, so I started to diagnosis the disc drive. After messing around with the system for bit it suddenly stopped powering on. I didn't smell any burning or hear any noises.I checked the PSU, it is reading stable voltage and is powering on a different PS2.The power LED glows on a different system. (removable part)The power LED changed to 'green' on a different system after pressing the power button.The solder/connections were refreshed on the USB ports, AV connectors, power connector, and the controller ports.The fuse near the power connector is still intact.I have almost no experience with motherboard level repair. I am checking shorted capacitors with my multimeter, but I don't think I am finding any.Any tips or suggestions? I am determined to fix this and improve my skills!Tell me what to do!My multimeter and PS2 board.https://imgur.com/a/diZkE2B

author: MathWizard
author_rank: Super Contributor
timestamp: February 11, 2023, 11:10:33 pm
content: So is the PSU an external brick ? IDK the PS voltages, but I'd guess whatever enters the PS, would power a bunch of lower voltage rails, like 5V, 3.3V, 2.5, 1.7, stuff like that for a bunch of chips.I'd start at the input, and try and find the main power sections, there's probably a standby rail too. Go around and find big inductors, most of them would very near a controller chip, making some voltages rail. With any luck, at least the power controller chips, would be labelled and have public datasheets. I'd lookup as many chips as I could, and on the PCB's see which ones are getting power.There'd be linear regulators too, like 3 terminal ones, like for analog and digital voltages rails, on stuff, it's common to see 5V made with a DC-DC SMPS, and another 5V rail from a linear regulator.The rails should power up in a certain order too. PC motherboards and GPU's they just use a few AND gates and ENABLE pins and Power-Good pins on chips, to do that.If you were lucky, the problem is just in the power sections. I'd find that a lot easier to track down that some digital problem.Maybe it's just the switches/buttons are dirty too.I'd recommend soldering on a few wires, it's super easy to touch the wrong thing with the probes, or have them slip. But I find even that is a nightmare on mobo's, I've damaged traces just trying to get test wires on there.
PS2521/PS2520 Repair Help - Page 1
Forum section: electronics / repair

author: rfdes
author_rank: Regular Contributor
timestamp: August 14, 2024, 11:01:59 pm
content: I am experiencing a problem with one of the calibration steps with this power supply.When attempting to calibrate the 'Channel 3 offset current' step, I am getting an error -96 CALIBRATION CURRENT OFFSET ERROR.All other calibration steps pass without issue.I've found no issues such as DAC problems, etc. that are suspicious.Is there anyone on the forum that has experience with this instrument that would be willing to discuss a troubleshooting strategy?Thanks