Repairing a 12 dc power supply.

[bustedparts]

I do alot of RC car racing. This is just a part of my hobbies. Anyway one evening I hear someone started cursing and I watched this person toss this power supply in the garbage. Well being the curious person  am I took it home to see what was wrong with it. Hoping it is something simple like a blown mains fuse. I opened it up and found the fuse blown and I replaced it. When I power it back up and turn it on it quickly blows the fuse. No I have been sitting on this unit for about a year because I knew I was going to study more on the electronics and this would make a great repair project. So I contacted the manufacture and I asked if i could get a diagram of the unit. I could not get one due to they dont manufacture them . So getting a schematic is out of the question. So now I need to reverse engineer it in order to properly test the circuits to find out what isn't working . So I am looking for pointers on how to draw out a schematic in reverse order.  Or maybe a guide on a proper work flow. It is something I have never tackled and any advise would be awesome.

[jeroen79]

Brand and type?
Can you post some good pictures of PCB?

[CJay]

Have paper, pencils, a multimeter, a bright light and the 'net to hand.

Draw small sections of the circuit first, find the controller chips and datasheets, they'll probably have an application circuit in there which can make your life a lot simpler, most manufacturers don't stray too far from the application notes for commodity items.

The bright light can help if it's a fibreglass board as some are translucent and you can trce tracks on a double sided board by holding it up to the light.

The multimeter because you can use the continuity function to trace connections and 'buzz out' transformers, chokes etc.