Amiga PSU headache

First ill try and explain the situation, Ive got a working Amiga currently at TC's awaiting a board from kipper to be fitted when it arrives, obviously I didnt need to send the working psu so that stayed here, just the other day another A500 arrived with a non working psu, opened that up and saw the fuse had blown, changed that and behold, much smoke! Never actually tried it on the Amiga though which is probably a good thing!

Anyway, plugged my working psu into the Amiga and turned on, red led steady along with the caps lock light, then after a few seconds both start to blink, and faster, dimming in and out. The psu was making a noise in time with the blinking lights.

Reseated all the chips and tested the psu, some very odd voltages going on there, 3v on the -12v line?

Next step was I took apart a PC psu and recabled it Amiga stylee making sure I had all the wires in the proper place and grounding the green wire in the psu for "always on", turn it on and away goes the fan, plug it into the Amiga and it shuts the psu down.

Im a bit stuck now guys! Any ideas?

Maybe there is a short somewhere in the Amiga ? Did you check the power connector and also the insulation between the motherboard and the bottom plate ?

Also try it with the disk drive unplugged as that might be shorting.

http://img.tapatalk.com/d/14/04/24/yva2uta3.jpg
tried without drive attached, still the same and i cant find any shorts around the power socket. Tried with the whole plate removed too. In the psu i noticed a different 5v, its in the picture as 5vsb, the one i have it in is just 5v, wouldnt make any difference would it?


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Well I just checked the voltages on the Amiga plug side and they are correct, +12v top left, -12v middle, +5v bottom right and 0v/GND on the rest, stumped!

mate could you take a wider shot?

that dont look like an amiga supply.


if you look at the picture closely there is a place for pg(power good) 5 volt vsb is normally for pc motherboards to power the reset/power circuit for the psu to turn it on.its only rated at about 2 amps max.

probably a good idea to look for any other connector spots on the board.

Roy's right that's not Amiga PSU. It looks like a PC PSU and if it is. The PG should go to the +5v line, why is the red wire in J2. It should be soldered where the other red wires are. I have a PC PSU and it works great..

Mike..

Quote:

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Originally Posted by roy_bates

5 volt vsb is normally for pc motherboards to power the reset/power circuit for the psu to turn it on.its only rated at about 2 amps max.

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If that - earlier ATX specs go as low as 0.1A, and I wouldn't be surprised if a random brand PSU with a 2A rating on 5VSB doesn't live up to the spec but is more like in the 1A range (sufficient for power-on from the PS/2 ports and Wake-on-LAN events).

Yep its a pc psu, that red wire in j2 goes to the fan, ill take a pic of the specs


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http://img.tapatalk.com/d/14/04/25/a5esuhe5.jpg


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its the board we need to see bud,its just to see what to wire where.

http://img.tapatalk.com/d/14/04/25/4uhu6epy.jpghttp://img.tapatalk.com/d/14/04/25/e6uzuze2.jpghttp://img.tapatalk.com/d/14/04/25/a7a4aty2.jpg the green wire is being grounded from underneath btw.


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