Old XBox no power

[edy]

Hi folks,

I'm working on a repair for a friend. His old original xbox is dead. I opened it up and most obvious thing I see is lots of leaking caps on the motherboard (see photos). I don't see anything on the main power supply... Does anyone know the pin outs of the power cable to the motherboard? is it the same as an ATX CPU power supply cable? Do I need to short some sense pins and have it drive a load like when you are testing a CPU PSU or is there an easier method? My main instinct is just to go out and replace all those leaky caps and hope for the best. If that doesn't work I can go in deeper but I don't really want to waste too much time on this one.

[SeanB]

PSU secondary caps are bad as well, and the higher ripple current has helped off the motherboard capacitors as well. change them first and see if you get voltage out of the PSU first.

[edy]

Here are more photos of the motherboard. Notice the 5 identical nichicon 3300 uF 6.3v caps which look crusty right at the main power input for the MB. The smaller caps look ok.

[edy]

Here is the PSU. I see no obvious physical damage. No bloated caps. Fuse intact. Can I test voltages on the cable running to the motherboard and that's it? Or do I need to be more thorough? Not sure where to start first.

[SeanB]

Plug in a standard PC power supply to the mainboard, or test the PSU to see if it works. I suspect those caps there, they are a cheap brand and might just have not popped on top but vented out of the bottom. You should get 5V and 12V out of the PSU.

[edy]

I plugged in a standard PC supply and no boot. The fan or at least drives should have made some noise, and there should be a light.

For sure those motherboard caps are gone... I'll have to change those no matter what. Then if it still doesn't work I can try my PC PSU... If it works then I know the Xbox PSU is also bad. But if it works ok then I will know the xbox PSU is functioning but I won't know how bad the ripple is and whether it will eventually fry the motherboard caps as well.

Can I use 3300 uF caps of higher voltage? My local supplier doesn't seem to stock 6.3v. They have 10, 15, 25v and so on.... radial electrolytics 105c. When I fixed my old TV I used 25V caps where they had 10v, no problem... that ok?

[AKM]

If they physically fit and don`t interfere with anything, there won`t be any problems. After almost 15 years of service, it`s a good idea to replace the output filter capacitors on the PSU.

[edy]

Ok I will have to take more photos of the PSU so I can figure out exactly which caps you mean.

[Rasz]

do NOT plug atx ps

http://home.comcast.net/~admiral_powerslave/atxpsu2xbox.html
http://s250.photobucket.com/user/malfeitorXVII/media/atxxbox15va2.gif.html

oh, you already did, oops, might of fried something

[AKM]

Output filter capacitors are obviously on the output (low voltage) side of the PSU board near the connectors going to the main board.

[edy]

Success!!!    

I was lucky and didn't blow the motherboard when I tried the ATX power supply. I changed those crusty nichicon 3300 uF 6.3v caps with some new nichicon 3300 uF 16v caps. Put it back together and powered it up, works a charm!

I didn't bother with the power supply board. I'm sure there are likely more issues but I don't have the time to invest in this and would become economically not worth it. The drive sounds a bit dodgy too.