Macintosh IIsi Power Supply Repair

D

DontGetHit

New Tinkerer
May 23, 2022
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Trying to make a long story short I recapped a IIsi power supply, it worked for about a week then started blowing fuses all the sudden when I plugged it in. Replaced D101, still blowing, replaced TH101 with a 0A one, fuse still blew, replaced it with a 2A one and this time nothing blows but computer not turning on. Am very inexperienced with testing different components so other than those two parts does anything else come to mind that should be replaced? I've heard moving onto the diodes is a good step. I know this is kind of vague but just trying to get an idea of if I should look into it further myself or just send it off to someone. Also at one point I put the PSU in the system and plugged it in, is there any chance I could've fried the board. Also also, I don't need a battery right? I am 99.9999% sure I was running it for a week without a battery but should I put one in?
Thanks!
 
Last edited:
SteveHere

SteveHere

Tinkerer
Oct 29, 2021
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St. Paul, MN
writtenoutput.blogspot.com
D

DontGetHit

New Tinkerer
May 23, 2022
8
1
3
SteveHere said:
I've struggled with a IIsi Power Supply also. When you do the recap, pay special attention to cleaning the boards (it's not too late to go back and clean some more). If the capacitor leakage was too bad, it can wreak havoc on the board itself. One of the gurus @techknight posted some good advice here...
https://web.archive.org/web/2021041...intosh-iisi-power-supply-diodes/?tab=comments
Good luck to you, I hope you are able to bring this one back!
Click to expand...
I've cleaned it as best as I can. I made sure to scrub the areas under the caps while I was recapping. In order to do a better job I would need to either ultrasonic clean it (which I don't have) or desolder everything and scrub it. I understand that some fluid would cause damage in the long run but could it really make it go from completely functional to dead in a week? I think it is just beyond me. Haha I know I posted here asking for advice but looking at the thing again I just have no idea where to start. Trying to get in contact with Joe's computer museum to see if he wants a crack at it, but if that falls through I might just buy a replacement. I'm pretty sure there is one on ebay that is still functional even without a recap so it should be squeaky clean, of course I will still recap it when it arrives.
 
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