Re: Help for fixing PSU
My friend gave me a very old PSU, G-tech (P) Model: LC-B350ATX, which even have no ATX12V 4Pins connector. He had replaced all the power transistors for main outputs and +5Vsb. +5Vsb is back. While shorting green wire to ground, it has main o/p but with hisssssss sound, furthermore, the main o/p is vanished when loading with an DVDRom. He give up and give it to me.
I further study it. I found the diodes and resistors connected to the two pull-push power transistors of the main supply is damaged. After replacing them, it can load with...
hkqq2010
Member
Last Activity: 12-02-2012, 11:21 PM
Joined: 09-30-2012
Location: HONG KONG
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Last edited by hkqq2010; 12-02-2012, 11:19 PM. -
Re: Help for fixing PSU
Sorry for late reply .... I am too busy ....
Yes, 2 is smaller, and the other is louder. now I use the louder one.
Besides, because of my interest, my friend give me another PSU with hisssss sound coming from the main o/p which he give up to fix it.
I will get the 222pF cap and 18V Zener from the shop ... maybe today.
Furthermore, I will go to see if I can get an 2nd-hand PSU but useful from the shop with the same model of my PSU and my friend's PSU, so that maybe I can fix them by replacing...Leave a comment:
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Re: Help for fixing PSU
Yes, with IC mod, it is better.
Recently, I fix another PSU, Bestec ATX300P5WB, which used TNY276PN for its +5Bsb. Thanks for "[B]everell [/B]" who provide me the similar circuit, I can easily found out TNY276PN was defective.Re: Help for fixing PSU
Yes, with IC mod, it is better.
Recently, I fix another PSU, Bestec ATX300P5WB, which used TNY276PN for its +5Bsb. Thanks for "[B]everell [/B]" who provide me the similar circuit, I can easily found out TNY276PN was...Leave a comment:
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Re: Help for fixing PSU
Thanks for your patience and useful info. But I have no 222pf cap on hand. I need to get one with the 18V zener soon.
I see ... thanks for useful info.
I had already mixed with other AZ431, and can't identify it now.
Thanks for your suggestion, but I get one good PSU from my friend which has the same EE-19. I used it to test all my 3 EE-19, they are all good with no single sound and keep +5Vsb at +5.0V.
Besides, I had tested all my AZ431, C945...Last edited by hkqq2010; 10-25-2012, 12:31 PM.Leave a comment:
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Re: Help for fixing PSU
Sorry that I haven't any RMS meter. Besides, I am also wondering the ability of my multimeter dealing with AC reading. When I checked the AC Voltage or DC Voltage before D502 and D503, it gives out 1.9V.
1. Vow, you are really expert, you even know the design of T3.
The resistance of T3 (isolated) is 4, 0.6 and 0.1/0.2 ohm.
2. I haven't any 18V zener, I will get one next time I visit the shop. Is it really 18V? Can I get 16V or 20V or something? It will be more easy.
3. I...Leave a comment:
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Re: Help for fixing PSU
Temporarily no. I want to dedicate with +5Vsb first. Maybe later .......Leave a comment:
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Re: Help for fixing PSU
I will extract an EE-19 from a good PSU to have a trial later.
Thanks for your great info again....Leave a comment:
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Re: Help for fixing PSU
Thanks for your reply. Yes, the bridge, 2 push-pull power transistors and MOSFET of +5Vsb are all burnt, and they are all replace.
Ah, luckily, the primary caps are ok, caused I had replaced them for test. I think they are ok because the duration is too short. Besides, it is 200V vs 230V anyway, it is not exceed too much.
Thanks for your reply.
Haha ... he has another new PSU, he don't want it back. It is totally on my hobby now.
Yes, I use...Last edited by hkqq2010; 10-23-2012, 09:48 PM.Leave a comment:
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Re: Help for fixing PSU
Thanks for your suggestion. I had replaced C503 but with no luck, there is still little hum sound. Any further suggestion??
BTW, the PSU is EnerPlus PE380 which was dumped by my neighbour who said it is damaged by his little son by setting the switch to 110V. There are many components damaged. I am very interested to know whether I can fix it and how many efforts and $$ to fix it.
Thanks for your suggestions. I had replaced C503, C507 & C508, but there is still a little hisses sound. I even...Leave a comment:
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Re: Help for fixing PSU
Thanks for your reply.
I am sorry that I made a terrible mistake. I found that it is caused by offload of 12V. After I re-connected TL494, exciting transistors and some other components, it abruptly drop to 2.5V. After replacing C506, it back to 11V. But it still can't provide any output. I will continue to try to fix it when I am available.
About hum sound and primary caps, I will keep them in mind. When I try it next time, I will deal with it.
Many thanks again....Leave a comment:
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Re: Help for fixing PSU
Some info I want to add, it is an atx PSU, and there is "hum" noise from T3.Leave a comment:
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Help for fixing PSU
Hi guys,
I have a dead PSU with no output at all and fuse burnt. After replacing power transistors and some resistors, the +5Vsb is back now. But I found the Vcc of PWM TL494 is over +30V which should be around +12V. Here is the diagram of the related circuit.
[ATTACH]49420[/ATTACH]
Is there anyone could give me some hints which part I should check it first?
Many thanks in advance.Hi guys,
I have a dead PSU with no output at all and fuse burnt. After replacing power transistors and some resistors, the +5Vsb is back now.... -
Re: Looking for a Bestec ATX-300-12E circuit Diagram
Thanks for your help, after I replaced the TNY276 chip, it back to work now. I am using it to drive the PC which I type this reply.
Many thanks once again....Leave a comment:
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Re: Question about Varistor
Ooooo ... too bad to hear " ... not ... easy ..."
Anyway, I will try to fix this problem for my hobby.
Thanks for the suggestion. I will test them one by one.
I use a PC with AMD Athlon 64x2 and no graphic card to test it.
Thanks for your reply. I will try to fix this cheap PSU when I have time....Leave a comment:
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Re: Question about Varistor
Sorry, typing eroor.
It has intermittently noise....Leave a comment:
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Re: thermaltake tr2 430w
Vow ... it is really a good info ...
Althounght I do not fully understand all of it, I had copy it down. I will re-read ... re-read and re-read it later.
Thanks for your explanation and teaching.
Many thanks....Leave a comment:
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Re: Question about Varistor
Yes, I intend to replace all of them.
Btw, I had another PSU which stop to work. After I fixed, it now turn to work, but with some intermittently. Any suggetion which part I should check of it?...Last edited by hkqq2010; 10-08-2012, 08:31 AM.Leave a comment:
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Re: Leadman LP-6100E problems
This really is a very good practice.
In the past, when I first to repair PSU, it burn me so many fuse. Besides of fuse, it is also full of scare caused it always accompanied with some flash and a little flame. With a light bulb, it is safer.
I would use a 40W light bulb rather than 25W, caused it provides sufficient current to drive the PSU 12V fan when testing....Leave a comment:
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Re: Question about Varistor
I see ... Many Thanks.
...
Leave a comment:
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Re: Question about Varistor
Thanks for your reminding, I will go to choose 130V AC varistor.
BTW, althought I know varistor is use to protect device from surge, I don't know its exact mechanism. Please forgive my foolish, I want to know how the varistor protect the electronic device. Does it work like fuse?
When there is surge exceed a specific voltage, it becomes an electrical crowbar to let the current go throught it to ground, instead of going inside the device. Is it correct? Does it burn out like fuse? One of my varistors becomes several K ohm,...Leave a comment:
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