Mac Classic II - Blank Screen Upon Startup

[steelphantom]

As some of you may recall, I won a Mac Classic II on eBay several months ago. It worked fine when I first got it. I messed around with it for a few days and then put it on a shelf on my desk. I took it down just now to start it up again, and while everything sounded good, no video came up on the screen! I waited for a few minutes, and still nothing! I'm really at a loss as to what could have happened. Any ideas?

 

[aquajet]

I can recall fixing a Mac Plus some time ago with the exact same problem. Turned out to be a cracked solder joint on the analog board, on the connector for the logic board cable. I discovered it by manipulating the cables around and noticed the image would flash on and off the screen and confirmed it with a magnifying glass. If you're brave enough, you could try that. Or maybe just give it a swift slap on the left side.

 

[steelphantom]

I can recall fixing a Mac Plus some time ago with the exact same problem. Turned out to be a cracked solder joint on the analog board, on the connector for the logic board cable. I discovered it by manipulating the cables around and noticed the image would flash on and off the screen and confirmed it with a magnifying glass. If you're brave enough, you could try that. Or maybe just give it a swift slap on the left side.

Well, I tried the swift slap technique to no avail. I also opened it up to check everything out inside and couldn't really see any cracked solder joints. I'm no expert, but everything looked pretty good to me. Could it be possible that I have a dead CRT? If so, I'm not so sure I want to go through the trouble to replace it.

 

[macEfan]

its highly unlikely that the entire CRT would die. Most likely, its bad solder joints, or a bad analog( video) board..

 

[aquajet]

As mac mentioned, it's extremely unlikely that the CRT is dead.

Bad solder joints are difficult to see without close examination, preferably with a magnifying glass. If you haven't done that, I would suggest doing so. Otherwise, it's probably a bad component on the board, in which case I would just try to locate a replacement on ebay or something.

Good luck. I hope you can figure it out.

 

[steelphantom]

As mac mentioned, it's extremely unlikely that the CRT is dead.

Bad solder joints are difficult to see without close examination, preferably with a magnifying glass. If you haven't done that, I would suggest doing so. Otherwise, it's probably a bad component on the board, in which case I would just try to locate a replacement on ebay or something.

Good luck. I hope you can figure it out.

Ok, so we've ruled out the CRT. I'll open it up tomorrow and check everything out again. I'll wiggle the wires around too and see if I can get any video. When I open it and fiddle around in there, are there any safety issues (e.g. having an electrical charge held by the CRT shock me )? I just want to make sure nothing goes wrong while I'm messing around with electrical components. Thanks for your help, aquajet and macEfan!

 

[FullmetalZ26]

Definitely excercise caution around the CRT, as it can hold enough residual current, even after being turned off for a little while, to throw you across the room. Particular areas of interest are the suction cup on the top-right side of the monitor, the thickly-insulated cable running to it, and the back end of the tube where the elecctron gun and its associated circuitry is.

I'd also recommend giving the SE Support Pages a look. While much of the information on the site is fairly machine-specific, the analog side of things should be pretty much the same, and at the very least you could get some ideas from reading over the page.

 

[steelphantom]

Thanks for the link! I'll read it over and see if I can come up with anything. Oh, and I'll be very careful around the CRT if I decide to go in there again for a look.