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[spirantho]

Can anyone help with this? I've recapped the board as it was having trouble.. but it's still having trouble. Used two different new ATX PSUs via an AmigaKit adaptor.. but it's only 4.7V on the +5V line, which means it most of the time doesn't boot up.

This is with any hardware on board, by the way (not even a CPU card sometimes!).

Does anyone have any suggestions? I'm just recapping the board... again....

[mechy]

Originally Posted by spirantho

Can anyone help with this? I've recapped the board as it was having trouble.. but it's still having trouble. Used two different new ATX PSUs via an AmigaKit adaptor.. but it's only 4.7V on the +5V line, which means it most of the time doesn't boot up.

This is with any hardware on board, by the way (not even a CPU card sometimes!).

Does anyone have any suggestions? I'm just recapping the board... again....

Where are you checking for voltage?

Did you check the motherboard plug and socket? these are notorious for corroding on the 5v pins and or the pins spreading apart and making bad contact( i stock these connectors if you need them). Assuming thats not it, i have found a trend in atx psu's that seem the 5v line is set low from the factory,since they concentrate on 3.3v these days i dont know if this is sloppy adjustment of the 5v side or they just dont care or?. I have had several new ones out of the box that barely make 4.8v on the 5v rail when checked loaded. Some older 200-300w psu's i find regulate the 5v rail better imho. the 4000 will happily run on a 200W psu in most cases.

[spirantho]

I've checked three PSUs now - the Corsair CX430, the Powercool 450W modular one (not a cheap one), and a little Atlas 350W one from my Peg-II. All of them run low, and there's large ripple on the 5V line and, I believe, on the -12V line. The voltage isn't constant, it tends to bounce around a lot on the -12V line especially. On the +5V line there's a large ripple and the voltage slowly decreases. It was at 4.58V at one point.

I'm measuring on the end of one of the caps (C188, by the SIMM sockets) and on one of the ICs.

Edit: the +5V wire on the ATX adaptor was getting hot before, as the AmigaKit adaptor only has one wire for the +5V and I think it was too much when loaded with the CSPPC etc.. I therefore soldered one of the other +5V wires from the ATX socket on the adaptor directly to the +5V pin on the underside of the socket, so I know it's a good connection.

[matt3k]

If you want an original power supply.

http://www.amibay.com/showthread.php?t=31837

Originally Posted by spirantho

Can anyone help with this? I've recapped the board as it was having trouble.. but it's still having trouble. Used two different new ATX PSUs via an AmigaKit adaptor.. but it's only 4.7V on the +5V line, which means it most of the time doesn't boot up.

This is with any hardware on board, by the way (not even a CPU card sometimes!).

Does anyone have any suggestions? I'm just recapping the board... again....

[spirantho]

Thanks for the link but I can't see that 3 PSUs can be bad with it! I haven't used my original 4000 PSU for years as I towered it, wonder if I still have the 200W PSU I used for ages... but I think that may have died.

[danbeaver]

I've opened up power supplies in the past to check them and found a few that have "trim pots" for adjusting the voltage. You may want to check; while you are in there check the quality of the cooling fan (some are rubbish and ought to be replaced), and clean out any dust that tends to allow overheating and power issues