Mac classic help

[Challenger 1983]

I got a new motherboard for my Mac classic it has no battery leakage

But I still get a checkerboard pattern on the screen

Please help

Thanks in advance

 

[bibilit]

Are you sure the Analog Board is ok ?

Low voltages can produce a checkerboard pattern. 

Can you advise what outputs the AB is delivering (at the HD Molex cable), if those are lower than expected (around 9/10 volts for the 12 V and 3/4 volts for the 5 V one) you have got a problem there.

You can try to use an hair dryer to heat the board, probably boosting voltages a bit.

http://appletothecore.me/files/leaky_caps.php

Analog Boards are known for leaky caps also.

 

[Challenger 1983]

Should I use the hair dryer while the computer is plugged in

 

[bibilit]

of course, but check before outputs.

If outputs are low, chances are heating the board on the lower right side will creep up voltages enough to get a working Classic... for a while.

IIRC 8 capacitors at least should been replaced (1100 uf/16v - 2200 uf/16v- 2200 uf 35v - 450 uf/16v) 

 

[Cory5412]

Moved to Compact Mac subforum.

 

[Challenger 1983]

I do not have the tools to measure voltage

 

[Compgeke]

Hit up harbor freight and grab a $5 mulitmeter. For testing PSU voltages it'll work fine.

 

[bibilit]

I do not have the tools to measure voltage

As a collector, this  kind of tools is a must have.

Hit up harbor freight and grab a $5 mulitmeter. For testing PSU voltages it'll work fine.

I agree.

 

[Challenger 1983]

Can I use an ATX power supply to test

 

[Compgeke]

I'm not trying to be rude, but one thing I will say is if you're asking I'd strongly advise against it. Multimeters are cheap and the first thing I'd grab before making custom stuff.

 

[Challenger 1983]

 

[Compgeke]

That rust isn't a good sign, looks a lot like battery damage, it's even in the battery location on the Classic. Are you sure there's no battery damage either from a leaking battery or exploded battery? Can we get pics of both the front side of the analog board, logic board and rest of the chassis?