Color Classic, once was working, now does not boot; mobo interface repair?

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Color Classic, once was working, now does not boot; mobo interface repair?

I picked up a Color Classic a few years back and had it running but with an error screen. I decided to give repair another whirl with a more deliberate diagnostic mindset, and can no longer get the machine to power on. I've ensured the power switch is up/on, the computer is plugged in, and the power button on the keyboard (should still be) working. I removed the PRAM battery, on the off-chance that was the issue, but still no joy. I took a closer look at the board and my caps look good to my eye. However, after flipping over the board, I did notice this:

It looks like the interface indicated has corroded away (the plating seems to be flaking off?). Would this cause issues powering on, and assuming it does, are there any pragmatic options for remediation? I was planning to go over the corroded bits with some solder, but thought I'd get some opinions here, first.

 

Just for throughness sake, here's the top of the board: top of board

It's not exactly in pristine condition, but I didn't notice anything too egregious, either. ¯\_(ツ)_/¯

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The PRAM battery in the

The PRAM battery in the topside photo shows a 1993 date code, so removing it was a good move regardless as they have the tendency to burst (yes, burst, not slow leak) and destroy the board.

Those contacts are indeed for the power rails to the board, so the corrosion you're seeing *may* be part of the problem. Testing each for continuity from the end of the contact to the through-hole on the board that it goes to should help you narrow down if that's the issue. Otherwise, investigating the analog board may be in order as it has many capacitors that are probably not in the best of shape if they've never been replaced.

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After letting the machine

After leaving the machine plugged in for a few hours, it now starts up fine ><

 

I did end up putting the battery back in to keep the internal clock working, but it sounds like I should take it out until I can get a new/modern replacement (thanks for the tip; "burst, not slow leak" was not the failure state I was expecting).

 

I'm now faced with the dreaded "disk with blinking question mark", so I guess my next task is figuring out how I'm going to get the OS on the drive (I don't have any installation disks at this point). On the upside, I did check the interrupt code and got `0000000F 0000000D`, which my duckduckgo-fu tells me means all hardware checks passed.

 

Thanks for the help; apologies for the premature forum post!

 

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Progress! (and setback!)

Progress! (and setback!) In my attempts to build a usuable/bootable floppy disc and get it recognized, I managed to get the first install disc for System 7.5.0 to run. Sadly, the install process mentioned a missing file issue (I think the floppies I'm using have passed the point of reliability) and gave me options to reboot or shutdown. I reboot, and now my CC powers on to the grey screen, but won't eject the floppy (even manual eject fails; paperclip button + restart with mouse down) or even do the boot chime. The interrupt key yields the tune playing, but the screen doesn't change, much less show the code.

 

It started doing this before I removed the PRAM battery, but has continued even after it's removal.

 

I'm kinda stuck on where to go with this next, and concerned I inadvertedly messed something up that I'm not going to be able to easily fix. Any ideas?

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I had the exact same

I had the exact same experience with a Color Classic recently. Pulled it out of storage, stone dead. However, others on the Internet said to leave it plugged in over night and try again.  Well, it worked and turns on every time after that. I don't know why it happens, but it does.

 

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rittwage wrote:... Pulled it
rittwage wrote:

... Pulled it out of storage, stone dead. However, others on the Internet said to leave it plugged in over night and try again.  Well, it worked and turns on every time after that...

 

I've encountered that in the past as well (easy thing to forget to try!). In this case, the power light on the front comes on and the screen displays the grey desktop as well, but no mouse cursor, no startup chime, no read from either floppy or harddrive, as far as I can tell. Will let it still for a bit and try again tomorrow, nonetheless.

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That's a classic symptom of

That's a classic symptom of failing motherboard capacitors. My own machine did the same thing. The electrolyte they leak doesn't have much of a tint to it, and they don't always leak when they fail, so sometimes it can be difficult to visually tell if they're still good. But at almost 30 years old, pretty much every Color Classic is going to need new caps in short order.

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Time to decide if I'm up to a

Time to decide if I'm up to a bunch of soldering, I guess ^_^;

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If you're not, I've heard

If you're not, I've heard good things about Amiga of Rochester in New York (https://amigaofrochester.com). Despite their name they've also got experience with Mac motherboard repairs.

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