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Macintosh Classic problem

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afaiello

Experienced Member
Joined
Mar 21, 2009
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I recently acquired a Mac Classic. When it turns on, a black and white checkerboard fills the screen. It had a bad battery on the logic board, so I removed it. I still get the problem. It has the internal hard drive as well. Any ideas?
 

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Unfortunately, Mac Classics are notorious for motherboard failures due to leaking capacitors. Over time, the electrolyte leaks out of the capacitors and corrodes the circuitry. Hopefully that is not the case with yours, but it is a common problem.

Some have actually reported success at using a dishwasher to clean off the leaked-out chemicals:

http://www.youtube.com/watch?v=zx_wllHbEOU

Steps taken to Fix the Classic:
1. Remove Chassies, disconnect cables and slide out motherboard
2. Remove the ROMs, these are four removable chips.
3. Ensure your dishwasher is empty.
4. Put motherboard in, and wash for 20 mins.
5. Put in oven at 50c (122 degrees F) for 20 mins
6. Put back in Classic
7. Put the machine back together.
8. Switch on and with a bit of luck it'll be working
Click to expand...
 
I may have found the problem. What is the type of component located at Y1 to the left of the onboard battery if the battery is positioned closest to you? It lays next to 2 small capacitors. It is missing off my board.
 
Y's are resonators Ithink, can't tell if something was soldered there since the picture sucks.

Anyway for checkerboard screen remove the RAM SIMMs (clean edge if needed) and reseat.
 
afaiello said:
I recently acquired a Mac Classic. When it turns on, a black and white checkerboard fills the screen. It had a bad battery on the logic board, so I removed it. I still get the problem. It has the internal hard drive as well. Any ideas?
Click to expand...

This is a common problem with the old compact Macs.

See here for repair info.
 
afaiello said:
I may have found the problem. What is the type of component located at Y1 to the left of the onboard battery if the battery is positioned closest to you? It lays next to 2 small capacitors. It is missing off my board.
Click to expand...

I can see no residue or outline of a component which used to be there, so most likely Apple didn't put anything in that spot to begin with. In any kind of electronic equipment, you will often see blank spaces on the circuit board which were marked out for a component but never had anything installed there, due to a design change or revision after the board layout was sent to production.
 
k2x4b524[ said:
whats that big brown splotch just above the audio jack under 2 capacitors?
Click to expand...

That would be dried up electrolyte from cheap, leaking surface mount capacitors.

I've repaired numerous Classic/Classic II machines with exactly your problem. It's always the capacitors.
 
I had to remove the battery because it went bad, and I also took out the battery housing from the board so I could clean everything. It should still work without the battery right?
 
I had a classic 2, those had RAM SIMMs. Anyway remove the socketed ROM chip and put it back in to see if that helps anything. You do have major capacitor leakage, not a good sign.
 
Ordered a new board for it. I'll post some pictures. It'll be added to my collection of an IBM AT and a Kaypro New 2. I even have the Apple Imagewriter II for the Classic.
 
afaiello said:
All the capacitors are good!
Click to expand...

Surface mount electrolytic capacitors are notorious for failing, usually they're only rated 2000-5000 hours and that drops with increased temperatures. If you don't have an ESR meter, the next best test is to give it a whiff. If it smells like fish, you've got some bad capacitors. Sometimes they fail electrically before leaking, but leaked electrolyte corroding things is very common. The PiP board in 90s Mitsubishi TV sets were infamous for bulk failures of these caps.
 
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