Beige G3 Desktop: No Power, no light, no fan, no nothing!

[DistantStar001]

Just as the title says, I got a beige G3 desktop that won't turn on at all. I also have a mother board, RAM, PSU, and just about all the other innards from a beige G3 tower as well.

The Tower board and PSU will boot (despite a battery explosion that took out its case). I even get the little floppy icon with a question mark when connected to a monitor. However, it won't power with the desktop PSU.

I have tested the Desktop PSU's fuse and it's good, but I get no standby voltage from the connector.

Also, the Desktop motherboard will not power regardless of which PSU I try.

So far, I've transferred over the RAM, CPU, and the voltage regulator board from the desktop board over to the tower board. and all work, both individually and in combination. I also transferred over the configuration jumpers and had no problems. The only thing I haven't swopped is the ROM board as it's rather stuck in the tower board. Still, I somehow doubt that would have prevented the desktop board from powering on.

The only modification to the desktop board is the P-RAM batter holder, which was swapped for a coin cell style.

My understanding is that the two boards should be identical, so the PSUs and other components should be interchangeable, but the Desktop board won't power up and the DT-PSU appears to be dead as well. Any suggestions?

 

[Unknown_K]

Beige G3 motherboards have a jumper for Apple or ATX power supplies.

Check capacitors for leaks also.

 

[Phipli]

Sounds like the desktop PSU and logic board are dead.

The PSU type jumper on the logic board being wrong just makes the logic board power on as soon as it is plugged in.

 

[DistantStar001]

Sounds like the desktop PSU and logic board are dead.

The PSU type jumper on the logic board being wrong just makes the logic board power on as soon as it is plugged in.

Can confirm both the DT motherboard and PSU are dead. However, it appears that the jumper does have an effect beyond automatic power up. When the jumper was switched to ATX on the DT-board (and connected to the Tower PSU), the fan came on after the power button was pressed. This did not happen when it was set to Apple. Even so, the DT-motherboard would not boot.

I also tried switching the Tower board to Apple and tried the DT-PSU but there were no signs of life (same when I tried the original tower PSU). I switched it back and with the original tower PSU, it boots fine.

So now what? Near as I can tell, I have a working motherboard. However, the PSU I have doesn't fit in a desk top case. So, is there a way to fix the original Apple PSU? It's kinda the only one I got that will fit in my current case.

Also, What could have gone wrong on the DT-Motherboard? Would a simple recap fix it? I don't see any signs of leakage, but then my eyes are far from perfect. I suppose it's not strictly necessary, since I have a good board to work with, but it would be nice to get the original board going again.

 

[croissantking]

So, is there a way to fix the original Apple PSU? It's kinda the only one I got that will fit in my current case.

Also, What could have gone wrong on the DT-Motherboard? Would a simple recap fix it?

We don’t know. More investigation is needed on your part. I’ve heard stories of a recap bringing a Beige G3 logic board back from the dead so you have nothing to lose by trying.