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Author Topic: Lisa 2/5 power supply (1.2 A)  (Read 146 times)

turbodiesel75

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Lisa 2/5 power supply (1.2 A)
« on: November 09, 2022, 10:56:55 am »

Anyone here willing to do a refurb/recap on my 1.2A power supply for Lisa 2/5 (for a fee, obvi)?
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Apple IIe, Apple IIc, Apple IIc+, Macintosh SE/30, Apple Lisa 2

stepleton

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Re: Lisa 2/5 power supply (1.2 A)
« Reply #1 on: November 09, 2022, 11:19:57 am »

Your profile says you're in Orlando, so people in the USA only I assume?  :)
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sigma7

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Re: Lisa 2/5 power supply (1.2 A)
« Reply #2 on: November 11, 2022, 03:52:46 pm »

Anyone here willing to do a refurb/recap on my 1.2A power supply for Lisa 2/5 (for a fee, obvi)?
I'm in western Canada so not a very economical option.

Since recapping is pretty common now for a variety of old electronic bits, presumably there are local folk with experience (other than the Lisa) that would just need the few details about the Lisa PSU capacitor substitutes.

There are some parts lists here somewhere.... searching....
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sigma7

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Re: Lisa 2/5 power supply (1.2 A)
« Reply #3 on: November 17, 2022, 02:36:16 am »

Quote
There are some parts lists here somewhere.... searching....
I haven't found anything with relatively recent 1.2A PSU cap substitutes... anyone have something at hand?

IIRC, the urgency is to replace:
  • the "across the line / line to ground" X/Y safety rated capacitors C1, C2, C3, C4 (especially if they are in a translucent package as they typically crack and then explode making a mess).
  • the primary switcher capacitors C12, C13 (as these are under the most stress and are the primary point of failure) .. use the best quality available with high hour and ripple current ratings and derate by using a higher voltage than the original (as long as it fits, which shouldn't be a problem as a modern capacitor is much smaller than a 1980s cap of the same rating)
In addition, one may choose to replace (or test and replace if not good):
  • the output filter capacitors C9, C10, C14, C15, C18, C19, C20, C21 (and perhaps C24, C27, C28)
  • any other aluminum electrolytics
Schematic is here: https://lisalist2.com/index.php/topic,292.0.html

The prolific Tom Stepleton started a census for the capacitors here: https://github.com/stepleton-xx/lisacapcensus/blob/master/620-0120_Power_Supply.txt

While you've got it apart, my preference is to add a small quiet fan to the top-inside of the PSU case as they run a bit warm otherwise.

I hope others will add further advice / comments / corrections ...
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fri0701

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Re: Lisa 2/5 power supply (1.2 A)
« Reply #4 on: November 17, 2022, 07:35:31 pm »

Sorry for the cross-forum linking - but a couple years ago, I recapped a number of Lisa 1.2A PSUs. I posted a list of caps that I ordered on 68kmla that I imagine are still mostly available: https://68kmla.org/bb/index.php?threads/lisa-ac-interference-coupling.35554/#post-383552

Please note, however, that I realized that I ordered some capacitors with less-than-ideal specs (hence the whole post about AC interference coupling). I swapped out the six 16V 2200uf capacitors with a different type, and all worked out great. There are notes on that, including what I ordered instead, further down in the linked thread.
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