Classic-Capacitor-Conundrum-Consultation

[davidg5678]

Hello all,

I have a Macintosh Classic Analog board that I am planning to recap, and I am now also the newest owner of four nonfunctional Classic logic boards.

I'm trying to put together a shopping cart to order all of the appropriate components, but I am having trouble deciding which parts to buy. I know that there are several analog board parts that commonly fail, and I would like to buy replacements for all of those preemptively. I know similar questions to this are frequently asked about the Classic, but I was not able to find any posts that answered all of my questions.

Here are the parts I want to recap:

1. One 630-0525 Analog Board (120 volts)
   
2. Two Classic I motherboards
   
3. Two Rev. B Classic II motherboards (they have two ROM chips)
   

I had little trouble finding appropriate logic board capacitors, but the analog board is proving to be a bit more difficult for me. I am hoping someone here has already recapped this model of analog board, and would be willing to share the shopping list of parts that worked for them.

It looks like I should buy some 1N148 diodes, a CNY17G-3 Opto-isolator, and a IRFBC40PBF MOSFET for the Analog board. Are there any other commonly defective analog board parts to be aware of? I'd much rather buy everything I might possibly need at once than pay $10 to ship a 30 cent component.

I'd appreciate any advice about fixing these Macintosh Classics, as they really seem to be the trickiest Compact Mac to repair. I'm looking forward to seeing this (formerly battery-damaged) Classic chassis display some Flying Toasters once again!

Thanks!

 

[dochilli]

Classic AB have most often problems with:​

TDA4605, CNY17G, IRFBC40, DP3 and DP4 (1N4148).​

Sometimes the two RIFA capacitors (CP19 & CP38) are cracked.​

 

[karrots]

Here is the parts list I used on my Classic II analog board with the same model number. Includes digikey part numbers.

https://docs.google.com/spreadsheets/d/e/2PACX-1vSV2LyGPEhFxpr9oA6FZ2DG7m42-P6yyeyOlBUpjrZJ2qcMCRyWYQzCNh56eypgUVyW4OP-M_NmQE2-/pubhtml

 

[jimbojones]

I bought caps from here recently and they worked well. May be a little more expensive than buying individually, but the kits save the hassle and aren't crazily priced:

https://console5.com/store/computer-cap-kits/mac-68k-cap-kits/mac-classic.html

 

[davidg5678]

Thanks, everyone!

I just placed my (ridiculously large) Digi-Key order. Hopefully, I will be able to bring a few Macintosh Classics back to life in the coming weeks. I'll try to keep this thread updated, as I am sure there will be some troubleshooting in my future.

 

[AndiS]

Hi!

Just writing to tell you that you are not alone. I have a Classic opened and waiting to be recapped for a few months now (Logic and Analog board). I could have used the cosole5 link a bit eralier, since I had to check all caps myself. Well at least I have something to compare notes

I hope there is some time during holidays - keep the soldering iron hot!

 

[davidg5678]

Hello,

I am working through recapping my Classic's (630-0525) analog board, and I have another question about component values. DP5 and DP7 both looked very saturated in cap goo (the metal turned green), so I decided to pull them both off of the board. Unfortunately, my Isopropyl alcohol took the labels off of them. I have some EGP30D diodes on hand, but according to schematics for a slightly different board revision, only one of the diodes would work.

Is it safe to use two EGP30D diodes, or do I need to buy some new parts?

Thanks!