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afaiello
August 10th, 2010, 07:32 PM
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?

vwestlife
August 10th, 2010, 07:50 PM
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

afaiello
August 10th, 2010, 07:52 PM
All the capacitors are good!

afaiello
August 10th, 2010, 07:54 PM
Does it need that onboard battery to function? I know it holds system settings, but is it required to boot?

afaiello
August 10th, 2010, 08:21 PM
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.

afaiello
August 10th, 2010, 08:23 PM
screwdriver points to it

Unknown_K
August 10th, 2010, 11:51 PM
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.

Anonymous Freak
August 11th, 2010, 12:10 AM
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?

This is a common problem with the old compact Macs.

See here (http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#CheckerFlag) for repair info.

afaiello
August 11th, 2010, 02:15 PM
I don't have any SIMMS installed, just the expansion card. And yes, something was installed there. Here is a picture of what it should look like in a better picture (took it from phone, sorry haha). http://blog.computime.it/wp-content/uploads/2007/11/mac_classic-board-t-r.jpg

vwestlife
August 11th, 2010, 02:24 PM
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.

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[
August 11th, 2010, 02:32 PM
whats that big brown splotch just above the audio jack under 2 capacitors?

glitch
August 11th, 2010, 02:47 PM
whats that big brown splotch just above the audio jack under 2 capacitors?

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.

afaiello
August 11th, 2010, 02:48 PM
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?

Unknown_K
August 11th, 2010, 03:35 PM
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.

afaiello
August 26th, 2010, 08:47 PM
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.

james1095
September 16th, 2010, 01:24 PM
All the capacitors are good!

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.

tezza
September 16th, 2010, 05:59 PM
Some have actually reported success at using a dishwasher to clean off the leaked-out chemicals:

Yes, certainly worked for me!
http://www.classic-computers.org.nz/blog/2009-04-13-mac-classic-2-dishwasher-fix.htm