Another dead Color Classic, where to start troubleshooting?

[einarmr]

Hi all,
I have acquired a Color Classic. According to the seller it “used to work reliably up until just a few months ago”, but now it’s completely dead. In a nutshell, my question is: How do I go about fixing it?

I’ve pulled out the logic board, and it looks just fine (but not recapped, yet). I haven’t looked closely on any of the other components yet. Any ideas?

 

[cheesestraws]

Colour Classics are ... fragile, moody, and not easy to work on. Welcome to hair-tearing exercises!

Recapping should be your first call. Especially recapping the analogue board: they're all stuffed these days, they were built down to a cost and it shows. Recapping the AB is a task that may cost you your sanity, but it's the price one pays for having these machines, I'm afraid. The AB in the CC.

You absolutely need to recap the logic board before any cap goo gets to the Egret chip. That said, I'd do one thing at once - recap the AB, test it, recap the LB, test it.

In case you didn't have enough headaches, the logic board has little metal loops on the back that make contact with the chassis to provide grounds for some of the bits of the logic board. But they don't make contact very well after the LB has been reseated several times. If you look at the bottom of the shielding, you can see the tabs that the little loops make contact with. I've had to bend those in a bit so they make better contact with the loops on basically all of my CCs.

That's the easy bits to start with. If it really worked reliably until recently, you may be lucky...

 

[einarmr]

Thanks! Do you have a link to a list of capacitors to buy, in order to recap the AB and LB?

 

[cheesestraws]

I used the list of capacitors for the AB here: https://amigaofrochester.com/recap-services/capacitor-list/

And the LB list here: https://recapamac.com.au/macintosh-colour-classic/

Side notes:

• I had to get the next case size down of tantalums compared to the ones that the recapamac page recommends, because my soldering is much worse than his. It's worth getting decent capacitors from a reputable company, firstly because tantalum capacitors get a bit incendiary if you offend them, and also because tantalum is a conflict mineral so you want to make sure you're getting them from a company that has as good a grip on their supply chain as is possible.
  
  
• From my experience, the analogue board list on recapamac is optimistic, and doesn't replace all the ones that have been knackered on some of my boards. You're better off using the list from Amiga of Rochester that I linked above, in my experience.

 

[superjer2000]

Agreed on all of @cheesestraws comments regarding the CC. I have recapped two CC analog board and its cousin the LC575. I recall somewhere near 50 caps plus a couple of diodes known to overheat. They are still tempermental. One great piece of advice from someone here is to watch the grounding tabs under the logic board…. Make sure they make good contact or else weird things, including colour issues on the CRT can occur.

 

[68kPlus]

Any updates?

 

[einarmr]

Nothing, essentially. I've spent the little time I have on my 660AV the past six weeks. That one works great, though.