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| Mac Classic II checkerboard and "half" brightness issue |
Posted by: PWGuy on 2019-10-19 13:27:33
I just bought a Mac Classic II that had a checkerboard pattern, so understand there is some re-capping work ahead of me. I inspected the logic board so far and it seems fine - will be reviewing the analog board soon. Is the checkerboard pattern a result of bad caps on the analog board or is that more the logic board? Both will need to be re-capped but I was hoping to focus on the analog board first because the caps are bigger/easier to replace, so am hoping the checkerboard issue is resolved by that - can someone confirm?
Also, I tried turning the computer on/off a few times to test it overall and it seems the monitor will exhibit "half" brightness levels as shown in the two screenshots below - one screenshot seems to be "full" brightness and the other is half - the checkerboard pattern, though, is the exact same. Same issue here with old caps that will be resolved with re-capping?
Having trouble with screenshots - will try again later
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Posted by: dochilli on 2019-10-21 08:44:08
I would recap the logic board first. Often the caps on the LB cause the checkerboard. Low voltages on the AB can be a result of leaking caps and can result in a checkerboard. Start with cleaning and recapping the LB. Take the battery out of LB especially if it is Maxwell!
For cleaning the LB isopropylalcohol is the best.
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Posted by: PWGuy on 2019-10-24 20:56:26
I would recap the logic board first. Often the caps on the LB cause the checkerboard. Low voltages on the AB can be a result of leaking caps and can result in a checkerboard. Start with cleaning and recapping the LB. Take the battery out of LB especially if it is Maxwell!
For cleaning the LB isopropylalcohol is the best. Thx!
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Posted by: dochilli on 2019-10-26 04:58:23
Did you check the voltages at the floppy port? Must be near 5 and 12 Volt.
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Posted by: PWGuy on 2019-11-02 14:04:43
Did you check the voltages at the floppy port? Must be near 5 and 12 Volt. No I will try that if the re-capped LB doesn’t address. More to come soon!
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