Recapped PowerMac 8100 PSU and now unstable

[LaPorta]

Re: Recapped PowerMac 8100 PSU and now unstable

Thank you for the reply. Please forgive me, as I do not know the difference between series and would appreciate being tought these differences. What would cause the instability? And, which one is it that is? If you can tell me from the list that I posted, I can figure out which capacitor on the board it was and post the requested photo...and possibly get a new part if required.

EDIT: Is that the 100µf, 50V ones? I can find them this evening per my notes on the board.

[sam_sam_sam]

Re: Recapped PowerMac 8100 PSU and now unstable

Ok I have a question for you about the capacitors that were chosen what criteria did you use

I checked one of them and you used EB series I would have use FR unless that series that you select was on the board originally there if use the wrong series it possible to have stability issues please show a picture of the the capacitor that you used a different series than what was originally on the board


Panasonic Electronic Component FR FC
Rubycon
United Chemi-Con KY KZE

[LaPorta]

Re: Recapped PowerMac 8100 PSU and now unstable

Attached are the photos. There is the small 120VAC in/out repeater board. The rest of the supply is two main boards at 90 degrees to each other. There are also two small daughter boards, one that had two caps that I replaced (the photo that looks like a cave). The other has what looks like small control circuitry. The undersides of the boards are very clean as well. Again, this worked fine until after the recap. Now it just shuts off after a few minutes.

[LaPorta]

Re: Recapped PowerMac 8100 PSU and now unstable

All were replaced - including the large filter ones. Will have to take more photos now to show the whole thing.

[sam_sam_sam]

Re: Recapped PowerMac 8100 PSU and now unstable

Can please post some pictures of the front and back of the board now after you recap it

Did you recap the daughter board or boards if it had more than one

Did you replace all the capacitors except the main filtering capacitor

If you did not replace all of the capacitors why not

Thanks

[LaPorta]

Re: Recapped PowerMac 8100 PSU and now unstable

Attached are three photos of the supply prior to recapping. They were not the best photos, mostly for my reference while I was working. There is a horizontal board, vertical board, and also a tiny board that is sandwiched in there that I had to remove to replace two or three more.

I'll also attach a list of the caps I used to replace the ones on it with.

[stj]

Re: Recapped PowerMac 8100 PSU and now unstable

pictures?
what caps did you fit?

[LaPorta]

Hello everyone,

This is my first thread, and I am new here. I am part of the 68kMLA forum, and I was referred over here by one of the members there who is a member here as well.

I have a power supply from a Power Mac 8100 (Delta Electronics, Model # DPS-225AB Rev: A0, Apple Part Number 614-0040). It worked fine prior but, being close to thirty years old, it was time to recap. I have done a lot of capacitor replacement, but am by no means an expert at all. I looked up the replacement parts and ordered on Mouser. All electrolytics were replaced with same capacitance and voltage rating (or higher voltage if the identical could not be found). After reinstalling, all seemed to be well: machine starts normally, everything runs. However, after about five minutes, the entire PSU shuts down all of a sudden. Dead. This is a soft power on power supply: it has no on/off switch, and it supplies a +5V trickle current to the motherboard for soft power on/off signaling. If I try to start it right when it dies, I hear a switch/relay click inside and then right off again. I can do it about three times till it won't do anything else. Only if I unplug the supply, let it sit for 15-20 minutes, then try again will it restart again, only to last for five minutes.

I checked output voltages, and all grounds are connected properly, all +5V read 5, all +12V read around 12, and all -12 are around that too. They all are consistent: the output is dead on until the supply suddenly shuts off.

At this point, I do not know enough to troubleshoot further. Anything else to try, and any more information I can supply to assist in figuring this out?