Re: Dell DA2 12V 18A PSU repair P/N M8811
Which Zener do you mean? There are 2, ZD201 and ZD202
There are no components on the secondary side of the little board, only 2 pins from the transformer.
Which SOT23 is marked NGV1? There are two SOT23 transistors, Q201 and Q202. Which one do you mean?
Ive got a scrap board with some 4N50's in a TO-251 package on it. 4N50 are rated 500V 4A.
One of those will fit in place of the 2SK2845 TO-92. Of course I will check they're ok first. Ive got a transistor tester.
...
technicalspecialist
Senior Member
Last Activity: 10-04-2023, 09:42 PM
Joined: 06-04-2010
Location:
-
Re: Dell DA2 12V 18A PSU repair P/N M8811
Thank you Antronics. Its been 9 years since I posted this. I thought no one would ever reply.
I still have the power supply and the daughter board. What version is yours? Is it M8811?
Looking at my original photos, all I need to know is what R201, ZD201, ZD202, Q201, Q202, and Q203 are supposed to be.
The rest of the power supply looks ok. Nothing burnt. But i'll check the rest of diodes and transistors for shorts anyway.Leave a comment:
-
Re: Vintage fan repair, copper wire question
I forgot to include the link to the calculator website that i used, here it is: [url]https://www.omnicalculator.com/physics/wire-resistance[/url]Re: Vintage fan repair, copper wire ...sistance[/url]Leave a comment:
-
Vintage fan repair, copper wire question
I currently have a customer's vintage fan on the work bench to repair.
It uses an induction motor with 4 poles. One of the poles is open.
I couldn't find the break so i cut off the original wire.
I have measured the other poles and the resistance is about 28 ohms per pole and I measured the diameter of the wire with my digital calipers and it is 0.35mm in diameter.
I need to work out how much 0.35mm diameter enamelled copper wire i need to order for it to be 28 ohms. I have used this calculator and it says i need 160.35 metres.
The enamelled copper... -
Re: Saitek Corona electronic chess computer repair
Ok, i will scope the CPU, RAM and ROM. The 1000uF cap and the black cap are the new ones i put on.
The originals were 100uF 16V so 30V definitely would have poped them whether the polality was reversed or not.
The BD438 is the main regulating transistor. At least some if not all of the TO-92s next to it along with the resistors and small blue capacitors (10uF) form some sort of latching power on circuit i think. There is no 5V output from the BD438 until i press the 2 buttons mentioned above.
I...Leave a comment:
-
Saitek Corona electronic chess computer repair
I am currently trying to repair a customer's Saitek Corona electronic chess computer originally from 1987.
More info: [url]https://translate.google.co.uk/translate?hl=en&sl=de&u=https://www.schach-computer.info/wiki/index.php/Saitek_Corona[/url]
It requires 9VDC from 6 C size batteries or a 9V transformer via the 2.1mm barrel connector. He told me that he accidentally connected 30VDC to it and 2 electrolytic caps exploded.
It no longer works properly but its not completely dead though. I can turn it on by pressing Play and Go buttons together, which is the normal...Last edited by technicalspecialist; 12-06-2018, 09:57 PM. -
Re: EZ-Cool ATX-650JSP ATX PSU recap.
Yeah, I really laughed a lot as well when I saw that 18A -5V rating. Its ridiculous!
its obviously a typo.
No motherboard in history ever drew 18A at -5V. Modern ones don't use -5 at all.
What did old boards even actually use -5V for? Did some ISA cards need -5V?
-12V can easily be regulated to -5V with a LM7905 anyway.
This PSU was taken out of a customers computer and I have already replaced it with a better quality delta PSU, which they have paid me for.
I will replace the GI...Leave a comment:
-
EZ-Cool ATX-650JSP ATX PSU recap.
I have been given this EZ-Cool ATX-650 JSP. I don't believe that it is actually capable of 650W but it seems reasonably well built with a decently sized transformer and heatsinks.
Please see photos before reading further.
I have removed all the output caps and labeled where they go and some other things in the photos.
The 5V and 3.3V output caps were all 2200uF 10V fukyuu's and were visibly bulging. I intend to replace these with 10mm 2200uF 10V panasonic FRs.
It has 2 12V rails each with its own pi coil and output capacitor, which are 10mm 2200uF...Last edited by technicalspecialist; 07-11-2018, 11:07 PM. -
Toshiba 32AV636D LTA320AP08 panel replacement
Hello,
I have a Toshiba Regza 32AV636D 32 inch TV which has a faulty panel.
The model number of the original panel is LTA320AP08.
I have found a panel on eBay that is model number LTA320AP05.
I have compared both models on panellook.com:
[url]http://www.panelook.com/LTA320AP08_Samsung_31.5_LCM_parameter_7502.html[/url]
and
[url]http://www.panelook.com/LTA320AP05_Samsung_31.5_LCM_parameter_7500.html[/url]
and they are very similar.
Before i buy the ebay item, i want to make sure it will be compatible.
... -
Re: Bestec ATX-1523F
No, those SME caps are not original but they have lower ESR than the originals and lowest ESR (about 0.8ohm if i remember correctly) of any of the 10uF caps I could find in my capacitor drawer or on scrap PCBs. They are from the CPU board of an old UPS with fried MOSFETs and bloated battery's. It wasn't worth fixing.
Other 10uF caps i tested had at least 1.2 ohms or higher ESR.
I have moved that power resistor away from the caps with pieces of wire and hot glued it in place on top of the optos. It doesn't actually get too hot, only slightly warm....Last edited by technicalspecialist; 11-13-2016, 10:19 PM.Leave a comment:
-
Re: Bestec ATX-1523F
Photos.
I have thoroughly cleaned the board with an old tooth brush and isopropyl alcohol since taking these pics. I'm have edited the photos to show where components are. Best viewed full screen in a separate tab....Leave a comment:
-
Re: Bestec ATX-1523F
I managed to get it working successfully. One of the four opto-couplers was open, specifically the one that signals the UC3842 to turn on. There was 4.98V across the secondary side LED when the PS-ON wire was shorted to GND. Since LEDs work on about 2V, I figured that it might be open so I unsoldered it and measured the resistance with my DMM and sure enough it was open. I replaced it with one from an old scrap Antec TruePower 550 thats in my box of scrap boards that I use for parts. That uses the same topology (single transistor forward) and similar PWM chip...Leave a comment:
-
Re: Bestec ATX-1523F
I have a bestec ATX-1523F on the bench at the moment that I am trying to repair.
The problem is that the main supply just won't start. 5VSB supply is working, but it is a bit low at 4.85V unloaded. It drops when i apply a 33ohm load resistor.
When I short PS-ON to GND, the green LED goes out but there is no voltage at all on any of the main rails.
Its not even trying to start, no clicking or pulsing. 5VSB stays the same. It is drawing about 9W from the mains.
I have replaced the following electrolytics:
All replacement...Last edited by technicalspecialist; 10-26-2016, 08:45 PM.Leave a comment:
-
Re: Dell DA2 12V 18A PSU repair P/N M8811
I think it does matter. There are 100s of transistor types out there all with different specs.
The side with the 4 pins and the burnt transistors is on the primary high voltage side. They're not likely to be just any 2SC, 2N or BC548/558 type. They probably need to be high voltage ones. Q201, Q202, Q203, R201 and ZD201 are what is burnt. R201 is completely black. The value of that resistor matters.
I couldn't find any schematics on the web of this PSU. OEM is Delta.
The model number of this little board is STDC-003....Last edited by technicalspecialist; 08-23-2014, 03:14 PM.Leave a comment:
-
Dell DA2 12V 18A PSU repair P/N M8811
I have aquired a Dell SX280 from a friend that wasn't working.
I opened the external PSU (part number: M8811) and found that some SMD transistors on a small daughter board are fried.
Its part of the feedback circuit. I think some pins on it got shorted to the metal shield/heatsink.
They're so badly burned I can't identify the part numbers.
I bought a replacement DA2 on eBay for £10 with the intention of looking inside to try and identify the components so I could fix the other PSU but the little daughter board in it is different.
The part number on the... -
Re: Samsung Syncmaster 245BW
Is your mains supply 120V US or 240V europe.Leave a comment:
-
Alpha Technologies Pinnacle Plus UPS repair
I run my own electronics repair business and I have a customer's Alpha Technologies Pinnacle Plus 1000RM Double conversion UPS on the bench.
It uses 3 12 7.2Ah Lead acid batteries and they are fully charged (36V).
I have contacted Alpha Technologies for the service manual/schematic but they are refusing to give/sell me a copy. They don't have it in europe.
I'm thinking that Alphla Technologies is not the real manufacturer and its actually made by some OEM in China.
Does anyone have any experience with one of these units? Maybe someone has a service... -
Re: Roland SP-303 problem, service manual needed
Its ok now, I emailed Roland and they sent me the service manual.Leave a comment:
-
Roland SP-303 problem, service manual needed
I run my own electronics repair business and I have a customer's Boss SP-303 Dr. Sample on the bench.
I've been playing samples and playing around with the effects for a while.
The problem is that it randomly freezes/crashes, can take a few seconds after power on or many minutes. Doesn't matter what I do, its completely random.
I have to switch it off/on to recover it. I have looked over both PCBs and they're ok. Can't see any cracks. None of the capacitors are bulging, no diodes, transistors overheated or shorted.
I am powering it from my variable bench PSU at exactly... -
Canon UC200 camcorder mod
I have a Canon UC200 camcorder that a friend gave to repair. I took it apart to work on the tape mechanism and noticed that the small PCB at the back with the AV output and a few buttons on
has a place for an S-video output connector and what I think is the place for a 6V DC power supply connector but neither are soldered on.
Also some associated surface mount ferrite beads, diodes and ceramic coupling caps are missing. I want to mod it to include these but can't without knowing what the values should be.
Does anyone have the service manual for this model or a similar...
No activity results to display
Leave a comment: