ax man cap run

also a TOPS LocalTalk card for a PC

gonna pass that to a friend for #marchintosh shenanigans 🫡

switcher silicon sanity check: rectifier bridge not shorted, main switching transistor not shorted, no shorts on the output rails 👍

#retrocomputing #macintosh

welp i'ma pull all the caps anywhere near the corrosion and check 'em, then see about cleaning up the mess

big bulk caps look clean and measure bang on spec on my cap meter

these will go back in ✅

#retrocomputing #macintosh #marchintosh

dead center of the corrosion is little ol' C19, lets pull that out and... ewww that's crusty not even going to test it STRAIGHT IN THE BIN WITH YOU ❌😵

think we found our culprit

of course this is the one i couldn't find a good match for at ax man

today i learned it may be one of the littlest electrolytics on the board that may betray you 🗡️

hope i got something in my stash

#retrocomputing #macintosh #marchintosh

also in the kill zone:

C62 looks clean and meters good ✅

C63 meters good, hope this is flux on it, don't have great replacements for these so i guess i'll let it fly ❓

#retrocomputing
#macintosh
#marchintosh

oh boy C67 on this sub-board is another 27uf 35v making a mess of things

TO THE BIN WITH YOU ❌

#retrocomputing #macintosh #marchintosh

C60 is right on the edge of the corrosion zone, lets pull that and check it

that's... 5.5% low? Nichicon PL(M) is 20% precision so i guess its in spec but it seems Nichicon PL are notorious for alkali contents corroding the leads and leaking so i should very much replace all these ☠️

really wanted to take this out and hose it down with QD electronics cleaner today but the weather is not cooperating

#retrocomputing #macintosh #marchintosh

this is turning into more of a detail job than i expected, i thought i could just replace some caps but nooo 😮‍💨

here's a trick i learned from watching clips of canon factory workers

got a pile of vintage Pentax 50mm F2.0 kit lenses collecting dust because you have way cooler lenses to use?

they make very nice hand lenses!

guess i spend some hours scraping at it with a dental tool until i get bored

#retrocomputing #macintosh #marchintosh

lot of nasty black corrosion bubbling up under the solder mask but it hasn't penetrated and the copper is still lookin' good

painstakingly scraped all the dodgy solder mask off

a good q-tip scrub with IPA to clear the flux, a vinegar scrub and rinse to maybe neutralize whatever alkaline cap juice is left, and a water rinse to clear the vinegar

and let it dry in front of a fan all night

#retrocomputing #macintosh #marchintosh

yup it's a good day to stay inside 🥶

#marchintosh