superjer2000
Well-known member
I recently revived my Mac 128k analog board by replacing all of the capacitors, doing the upgrades noted in Macintosh Repairs and Upgrade Secrets and replacing Q1 and Q2 transistors as well as U3 Optoisolator. I'm not sure what part(s) were bad, but the board fired right up after replacing these components.
I'm attaching the list of Mouser Part #s I used to complete this work in the attached spreadsheet (which also includes an inventory of the pre-existing capacitors on my board. I'm attaching a few pictures as well for how I changed out CR20 and CR21. Thanks to JDW for his list as well - I referenced it when going through my board to see if I was missing anything.
I couldn’t perfectly match lead spacing for some of the capacitors and I used some hot glue to ensure stability. There seems to be various schools of thought on hot glue for this type of work and I guess I’ll see if it causes any problems in the future.
One change I made after this was for C5 - I had to use a radial cap as I couldn't find an axial with the right specs. I had it sticking up (as in these pictures below) and that worked great for my 512kE test unit with a Clinton CRT but it wouldn't clear my 128k's Samsung CRT so I had to remove it and resolder it laying on its side.
I ordered replacement pins for the J4 connector as well so I could replace the 22 gauge wire with 18 gauge. I tried to order replacement J4 connectors but ended up with 4 pin versions so I just ended up using the pre existing connectors. I've got some new 11 pin J4 connectors.
I'm working on my Classics now - I have only found one list of capacitor parts but it didn't have diameters or lead spacing so I'm measuring those out for my A and B boards and will post once they are successfully recapped. A list of Color Classic analog board capacitors would be nice if someone had but I haven't come across one so that will be an eventual project.
View attachment Pre SE Capacitor and Upgrades.xlsx
I'm attaching the list of Mouser Part #s I used to complete this work in the attached spreadsheet (which also includes an inventory of the pre-existing capacitors on my board. I'm attaching a few pictures as well for how I changed out CR20 and CR21. Thanks to JDW for his list as well - I referenced it when going through my board to see if I was missing anything.
I couldn’t perfectly match lead spacing for some of the capacitors and I used some hot glue to ensure stability. There seems to be various schools of thought on hot glue for this type of work and I guess I’ll see if it causes any problems in the future.
One change I made after this was for C5 - I had to use a radial cap as I couldn't find an axial with the right specs. I had it sticking up (as in these pictures below) and that worked great for my 512kE test unit with a Clinton CRT but it wouldn't clear my 128k's Samsung CRT so I had to remove it and resolder it laying on its side.
I ordered replacement pins for the J4 connector as well so I could replace the 22 gauge wire with 18 gauge. I tried to order replacement J4 connectors but ended up with 4 pin versions so I just ended up using the pre existing connectors. I've got some new 11 pin J4 connectors.
I'm working on my Classics now - I have only found one list of capacitor parts but it didn't have diameters or lead spacing so I'm measuring those out for my A and B boards and will post once they are successfully recapped. A list of Color Classic analog board capacitors would be nice if someone had but I haven't come across one so that will be an eventual project.
View attachment Pre SE Capacitor and Upgrades.xlsx
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