Power Mac G4 MDD "Mirror-Door" won't power up

[AtariMan]

Re: Power Mac G4 MDD "Mirror-Door" won't power up

Thanks everybody. I managed to fix my MDD G4

[falcontech]

Re: Power Mac G4 MDD "Mirror-Door" won't power up

Hello
I also have the same problem with two power supplies of these samsung, I am changing all the components that are attached to the main heat sink for safety, I am also changing the large capacitor and I would also like to change the rectifier bridge, but with the number that is there above I can not find anything, someone can tell me the characteristics to put one like it thanks

[falcontech]

Re: Power Mac G4 MDD "Mirror-Door" won't power up

These are a fun fix. I haven't read this thread but used to work for a company doing these. The ACBEL was always caps, the 1000uf was the main prob not allowing it to start up, but good to do the others while you're in there, and the samsung ones were a little more difficult. it was always a diode or two and the mosfets. you have to remove the heatsinks.

Hello
I have a problem with an acbel, I can't start it, I have changed almost all the capacitors including the 100uf 400v, but it doesn't want to start, you can tell me what I have to change since you know this power supply thanks. (on the other hand I managed to repair two samsung) now it has become a challenge between me and him

[cheeky2]

Re: Power Mac G4 MDD "Mirror-Door" won't power up

Here are the photos as promised. Hopefully this will be helpful in the future.

I know it's an old thread but thanks for the picture It ensured a quicker removal of the heatsink without any extra points being unsoldered.
Found this thread very useful and aiding the quicker diagnosis of the failed PSU.
Just parts to order now

[cheeky2]

Re: Power Mac G4 MDD "Mirror-Door" won't power up

I know it's an old thread but thanks for the picture It ensured a quicker removal of the heatsink without any extra points being unsoldered.
Found this thread very useful and aiding the quicker diagnosis of the failed PSU.
Just parts to order now

A successful repair was carried out with the help of this information contained within this thread.
Just some advice the thermistor that is mounted on the heatsink is a right pain to solder in place. So I soldered some 3Amp fuse wire to both of the legs which is far thinner than the thermistor wire and used them as guides to pull the legs through the two holes to make the assembly of the heatsink far easier. This saved me a lot of time in trying to line up the wires of the thermistor. As if you don't both legs are near impossible to line up correctly blind and will just bend over as the heatsink is lowered into place.

[bzyzny]

Re: Power Mac G4 MDD "Mirror-Door" won't power up

Just wanted to say thanks to everyone in this thread, and the other related threads on here. Recently I repaired one of these power supplies thanks to the info on here and the capacitor list found on thehouseofmoth dot com. I had to do some digging to find suitable replacements for some of the parts, since I couldn't find them in stock from a reputable source. Here's a list to hopefully help the next person. The bridge rectifier and mosfets have slightly different specifications but they worked for me. Please verify for yourself that they are correct replacement parts for your PSU.

Digikey part numbers
Fuse: 486-1767-ND
Bridge Rectifier: GBU8JFS-ND
Mosfets: 497-3263-5-ND
Main cap (390uF 450V): 493-3238-ND