Dead Mac IIsi Power Supply

[CC_333]

Hi,

I just got my IIsi logic board recapped by uniserver (thank you!), but I seem to have had a stroke of bad luck .

I eagerly reassembled the machine, only to find that the P/S is now dead (I think). Nothing happens when I plug it in and press the power button.

There is some odd looking corrosion on several of the pins at the main connector, so maybe that has something to do with it?

Help!

c

 

[Trash80toHP_Mini]

Been there . . .

IIsi PSU: Catastrophic Failure! = 8-o

 

[uniserver]

i love this!

jt u are the man!

 

[CC_333]

Hi,

It wasn't like that, fortunately. It just isn't working.

I'm wondering If I can repair it, or if I should just go find a new one.

Suggestions?

c

 

[uniserver]

well you could take your PSU apart, and check this cap as in this thread:

http://68kmla.org/forums/viewtopic.php?f=8&t=20074&p=191365

Hey, how did the IIsi work before you sent the board to me?

When I tested it after the re-cap, it worked outstanding. - I had to scrape some flux off the bottom pads for the

Power Light / Speaker Combo, I started always reflowing those pads after mcdermd's run in with a sound chip IC issue, with a IIsi

Charles

 

[uniserver]

corrosion on several of the pins at the main connector,

That might be leaking electrolyte, after all gravity would take electrolyte in that direction (connector)

 

[CC_333]

Hi,

It worked perfectly before all this. I noticed this morning that the roof of the storage shed I've been keeping it in leaked, so that could've done something to it.

I thought maybe electrolyte too, when I saw what looked like a little bit running along the inside of a seam, not far from the connector.

It looks like I need a new one (or have this one recapped somehow, if it's not beyond repair).

How about a little "fingers crossed" or "good luck" smilie thing?

c

 

[uniserver]

take the PSU apart and let us know what you see…

also pull your Quadra 700 PSU and pull out the IIsi motherboard, use a couple books and see if it powers up that way.

 

[uniserver]

I have a LC575 power/analog board, I am messing with right now… there was a pair of 5500uf 10v Caps that looked to be slightly leaking the leads were turning green.

Not sure what the common problems are with these LC575 power boards. This one also does the same as yours, dead, will not power up.

I even RE-Capped the LC575 Logic board, It works now… tested it in the Color Classic.

Now I just have to figure out what is wrong with this power board.

 

[CC_333]

Now I just have to figure out what is wrong with this power board.

Yeah, troubleshooting can be quite a process, that's for sure .
I'll try the Q700 power supply and see what happens. I'm certain the logic board is OK, so I expect it'll work fine.

All the various drives should be OK as well, but I'll have to test them out once I get power to the machine.

Thank you for the help!

I really appreciate it!

c

 

[CC_333]

Hi,

I opened it up, and I found a little board with those little SMD capacitors, an IC with a bunch of small surface mounted stuff. The IC pins are corroded all over the place, and it smells slightly burnt (I think?). I don't see much corrosion anywhere else, but there are a couple capacitors which look slightly bulged, around the same area as this other piece.

I'm not sure if it's fixable :'( .

I can take some pictures of it upon request.

c

 

[uniserver]

sure take a few pictures... i am sure you can fix it good buddy!

If you don't have any luck, you can send it to me, I could probably fix it .

 

[CC_333]

Hi,

Well, no pictures yet, but I have discovered the likely problem: capacitors .

So it looks like the whole secondary section will have to be recapped, and probably the primary section for good measure

Those @!@##@!@! capacitors > .

If you don't have any luck, you can send it to me, I could probably fix it .

I might take you up on that. How much?
c

Edit: I tried the Q700 PSU, and it worked, so the logic board must be OK. The hard drive worked as well, which is excellent.

 

[uniserver]

i have no idea buddy.

Why don't you try first, I have faith you can do it

 

[CC_333]

Hi,

OK, I'll give it a try. Maybe I'll use the opportunity to recap a few other things I've been meaning to do (Color Classic, M-Audio Studiophile AV-40 speakers, etc.)

Thank you for your words of encouragement!

c

 

[uniserver]

Your welcome!

However if you have issues I can fix it for you.

 

[Trash80toHP_Mini]

If the recap doesn't work, there's always the hide the skinny lil' ATX PSU Hack! }

 

[CC_333]

If the recap doesn't work, there's always the hide the skinny lil' ATX PSU Hack! }

Yeah, I thought of that, but, with some work, I don't see why a recap wouldn't work (unless, of course, some unobtainable, important part has fried itself or something; if that were the case, I'd probably just get another IIsi PSU).
If I were to do that ATX conversion, I would be more inclined to do it to a IIcx/IIci/Q700, mainly because the PSU enclosure is more or less the same size as a standard ATX part, which would make it more or less* a drop-in replacement.

I just looked at it again, and the corrosion isn't too bad, actually. It's mostly on that IC.

c

*Aside from wiring it up so that it interfaces with the logic board properly.