Macintosh LC III Bodge-Laden PCB

macoslove

macoslove

New Tinkerer
May 14, 2026
13
15
3
Missouri
I am not sure about these bodge wires but I assume they are first revision last minute fixes, or at least that is the hope.

No chime or video output joy so lets see what some tasty new caps will do for it. Will there be gremlins hidden like with my Quadra 605? I certainly do not want to have green garbled video...

I need friends that have greater skills to teach me to be more capable on the diagnostic realm.

Anyone have info on these LC III's and potential things to look out for?
 

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macoslove

macoslove

New Tinkerer
May 14, 2026
13
15
3
Missouri
Well, here's to the next step! No destruction found from the fishy caps and for that I am thankful.
 

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speakers

speakers

Tinkerer
Nov 5, 2021
160
100
43
San Jose, CA
peak-weber.net
David Cook said:
Nice job.

C22 is reversed. That is, although you installed it in the way Apple marked it, Apple made a mistake. You need to flip it the other direction.

See https://recapamac.com.au/macintosh-lciii/
Click to expand...
I got caught by this a few years back. It's a decoupling capacitor on the -5V rail. The original aluminum cap didn't care but if you replace it with a tantalum that'll draw a large current under the reverse polarity. The LCIII PSU won't complain, but the -5V line will droop to perhaps less than -2V. The machine will still boot but, in particular, the serial ports won't work. Note: if you use a different PSU, as I did, it'll detect the overcurrent and refuse to run.
 
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