Mac Classic II checkerboard and "half" brightness issue

[PWGuy]

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

 

[dochilli]

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.

 

[PWGuy]

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!

 

[dochilli]

Did you check the voltages at the floppy port? Must be near 5 and 12 Volt.

 

[PWGuy]

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!