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ATX Power supply repair

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Advanced Member level 4
Dec 2, 2010
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I need for my tests some good quality power supply. I have 12v 2amp, 3amp etc. and few boost converters.

I recently found my old ATX power supply , Odeyssey 400watt ATX power supply (dated OCT 2005).
I thought may be if I could repair it without much effort it is worth keeping as an additional power supply. ( I have plans to take 5-8 amps if possible to charge my SLA battery).

(images are attached below)
it is one with 2 x 13007 at the primary and one more (5vsb) installed on the same heat sink.

I took out the STD 13007 and checked it, seems okay. but I have an additional 13007 which when checked I saw DVM reading between Collector and emitter ( like what we get with TIP122 -Epitaxial Darlington). is it normal?

The third one in the row I think is burned (see pic) , I cant read the no on it. when tried with dvm , diode mode - no reading at all.

I tried online to find part and found this page
the package and name is different but the inside is atleast 90% the same. it has a mention of C2057S transistor for 5Vsb. I searched online and found nothing. is it 2SC2057 ? I cant find that too. any idea about a possible replacement?


Look at this.


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Thanks for the reply. I found 5027 transistor and inserted. A 4148 diode next to it also was short. I turned on the power and the fan started and stopped (I only had it 'on' for a few seconds). The transistor was hell hot. Then again I turn on . transistor gets hot. doing this a few times, then I left in on for few minutes and I heard a blast, think the transistor is gone. what could be the possible reasons, something short? the two 13007 next to it , is not at all hot.

Ok, I replaced 4x RL207 rectifier diodes, Transistor J5027 with 13007. a shorted fuse, shorted c945 next to the third transformer (5vsb) and .
I turned it on ,, initially the fan started running and turned off. , I turned off the supply , I can feel something burning.
I touched, transistors are not hot, but 494 IC is getting hot. I turned it on again, 2-5 seconds , fan is running and blast, fuse gone. all turned off. The point to note is that usually when the PS is connected to the mains supply and turned on, nothing happens. Then we ground the green wire and if the PS is working okay then the fan starts running. Here I didn't ground the green wire. when I switched it on the fan started running (green wire is not grounded) . what could be short ?

/* I am trying to repair this becoz I needed a PS to charge my 100amp battery. yesterday I took PS from my desktop (which I don't use much nowadays and connected it to a boost converter, and successfully charged the battery. The battery is hooked to a solar panel, but now it is raining and sun is seldom seen bright. so I thought to charge it manually. new PS is not expensive nowadays but I thought I should try to repair this damaged one, if it doesn't cost me much(more than that it is fun to work on things like this). But it looks like it is not worth it if more components are to be replaced. I will try once more and then will stop */

better you go for new one , repairing smps is not so easy. and here is the schematic for smps


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