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Macintosh Classic II Questions


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Update: On the analog board, there were a few cracked solder joints. I had someone I knew re-flow those. Unfortunately, no progress has been made.

Still powers on with no chime and a blank screen. However, I did notice something really strange with the logic board:

 

Upon startup, I checked the voltages using the floppy port. They were in the correct range on the +12v, -12v, and +5v. Pretty much spot on. I check a couple minutes later with the machine still running, and the voltages had dropped significantly.

 

I'm guessing the logic board needs recapping, which is the next thing I want to do.

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Earlier in the thread, you said the tube had a faint orange glow. What makes you certain the CRT isn't powering on? On a very basic level, if the Mac doesn't boot, nothing will be drawn on the screen. One thing at a time here... Recap the logic board first. If the problem persists, only then should you focus on the analog board. The voltages you show tell me that the analog board is ok. I don't want to sound like a jerk, but I feel like a broken record. Again, recap the logic board, then worry about the other stuff only if the new caps do not resolve the current problem.

I said this before...

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Recap that logic board!!! And clean the logic board... I put it in the tub with 90% rubbing alcohol bath... toothbrush to get under the chips.. Use rubber gloves.. Those CAPS require replacing as everyone has mentioned.. It's the first thing I do when I get a machine.. I don't even power it on.. I do logic board then move to analog and power supply boards..

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I have a classic II that needed the recapping. It also happened that some electrolyte corroded a few VIAs and the board had to be lightly bent to make it temporarily work, so make extra attention to the damage BEFORE recapping, take some photos, these could come useful after. Also try to "divide et impera", the mac is composed of two boards, the analog and the digital. First you make sure that the power is good (measure it from the power cable with the logic board disconnected. Then you recap and try searching for issues until you hear the startup chime, and AFTER THAT you debug the screen.

 

And moreover, do some searches for larry pina's books. They are truly fantastic for troubleshooting.

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