Macintosh TV C195 pad ripped off

[wottle]

I was replacing the last capacitor on my Mac TV logic board (C195) and because it was a larger one, I tried to desolder it instead of using my usual push and twist method. Turns out there was a decent amount of leakage under the cap and the pad ripped clean off. The other one lifted a bit, but is still connected.

The problem is I can't see what the pad was actually attached to. I don't see any trace or connection point, so I'm not sure what I can even try to run a bodge wire to to fix.

Does anyone have a Mac TV logic board or schematic that will tell me what it should connect to? I thought maybe I saw some metal showing through underfeed, and scraped it a bit, but I didn't want to make things worse so I stopped. I was also trying to see if there was a trace connecting it to the via directly above the path, but I don't believe there is.

Any help y'all can provide would be greatly appreciated!

 

[Androda]

I don't own a Mac TV, but to my eye that capacitor pad probably goes to this via. It's the positive side of the capacitor (based on the curved silkscreen marking). If you check from that via to various other capacitors and chips, it will probably be connected to a power rail.

 

[wottle]

I don't own a Mac TV, but to my eye that capacitor pad probably goes to this via. It's the positive side of the capacitor (based on the curved silkscreen marking). If you check from that via to various other capacitors and chips, it will probably be connected to a power rail.

View attachment 6977

Yeah, that was the only one that seemed to make sense. Unfortunately, I couldn't get a wire soldered into that via , but I did find where the VIA is connected to pin 1 on the U26 IC to the left of it. I was able to get a bodge wire from that to the new capacitor. Unfortunately, I am unable to get the machine to boot.

Thanks for the suggestion. Anything else to try?

I might have to ship this board off to someone with better diagnostic skills / tools / knowledge. I think I can swap in boards from some of the other LCs in this time period (LC575, 520, etc). But I really would love to keep the original board's video / analog TV input.

 

[Androda]

Thanks for the suggestion. Anything else to try?

Unfortunately I don't know anything about the 520-like machines. Would be nice to have one for poking around at.

 

[wottle]

Unfortunately I don't know anything about the 520-like machines. Would be nice to have one for poking around at.

Fortunately, I spoke too soon. These Macs (for reasons I don't understand) sometimes need to be plugged in a bit before they'll boot. I left it plugged in and powered on (without pressing the soft power button) for a bit and went back and it booted up. My bodge wire work is horrendous, but it appears you were correct about that via being the connection for the positive leg of that cap.

Hopefully no one does what I did, but at least we have confirmation of the fix if it does. Appreciate the help!

 

[Garrett]

A completely healthy system shouldn't need to sit with power for very long in order to boot. To me this indicates some other power issue, probably with the analog board. Has that been recapped? If your bodge wire is making contact and you've tested with a multimeter, I wouldn't think the logic board caps are the issue.

 

[wottle]

A completely healthy system shouldn't need to sit with power for very long in order to boot. To me this indicates some other power issue, probably with the analog board. Has that been recapped? If your bodge wire is making contact and you've tested with a multimeter, I wouldn't think the logic board caps are the issue.

I did recap the analog board. I also swapped an analog board / CRT from a Performa 575 that was working last time I had the logic board in it and the behavior was the same. Also, the issue seemed to start (inconsistent ability to power on) when I recapped the first set of capacitor I had on hand. Over time, it seems to get more reliable (e.g. I had the machine unplugged overnight and I plugged it in and it powered right up after plugging in).

Is it possible the coda / egret chip has bad contacts or is going bad? I believe they are responsible for the soft power capabilities on these Macs.

Also, I've seen similar issues with the two color classics I picked up as "non-working". Both refused to power on, but after sitting overnight with the power switched on, would boot with the soft power button in the morning.

 

[This Does Not Compute]

Also, I've seen similar issues with the two color classics I picked up as "non-working". Both refused to power on, but after sitting overnight with the power switched on, would boot with the soft power button in the morning.

I had that problem with my first Color Classic, but the behavior went away when I recapped the logic board. It got better immediately afterwards, though, not gradually as your Mac TV board seems to be doing.

 

[wottle]

I had that problem with my first Color Classic, but the behavior went away when I recapped the logic board. It got better immediately afterwards, though, not gradually as your Mac TV board seems to be doing.

Yeah, I'm going to maybe try some more targeted documentation of the behavior to see if I can see a pattern.

On the plus side, it seems to be running well now. Newly painted mouse and ADB cable to match the keyboard and case, working TV tuner card, and a replacement Sony remote to control the TV functionality. Going to be setting up an in-home analog transmitter to send signals to channel 3 on it.

I'm not thrilled with my bodge wire capacitor fix, and will probably throw some hot clue onto it to stabilize it (It's held in place with a partially lifted pad on one side and a bodge wire on the other)