Screen Cuts Out on my Macintosh Plus.

[DistantStar001]

Just as the title says. The screen goes black after about 5 to 10 minutes of use. Hitting it on the side with the analog board will bring it back for a few seconds at best but with diminishing returns every time.

The good news is that the computer boots and loads an operating system. SCSI port works. Mouse works, The new floppy drive reads disks and ejects without a problem. All keys on the keyboard work, and I've tested several keyboards on this machine. But the screen still cuts out.

So far, I've recapped the entire motherboard, reflowed all the solder joints (as well as on the motherboard connector for good measure), and replaced the flyback transformer, with no success. Any ideas?

 

[Nixontheknight]

Just as the title says. The screen goes black after about 5 to 10 minutes of use. Hitting it on the side with the analog board will bring it back for a few seconds at best but with diminishing returns every time.

The good news is that the computer boots and loads an operating system. SCSI port works. Mouse works, The new floppy drive reads disks and ejects without a problem. All keys on the keyboard work, and I've tested several keyboards on this machine. But the screen still cuts out.

So far, I've recapped the entire motherboard, reflowed all the solder joints (as well as on the motherboard connector for good measure), and replaced the flyback transformer, with no success. Any ideas?

if you can, buy a plastic poker and poke around the analog board to see if poking at a certain spot causes the video to come back then out, and try reflowing the component that causes it

 

[cheesestraws]

Just as the title says. The screen goes black after about 5 to 10 minutes of use. Hitting it on the side with the analog board will bring it back for a few seconds at best but with diminishing returns every time.

This is almost certainly a cracked solder joint on one of the connectors on the analogue board, probably the one between the analogue board and logic board. Two of my pluses had this, and both of them it was this connector. They are known to crack because of the heat/cool cycles they are subject to.

You may well find that reflowing the solder on that connector will help.

 

[DistantStar001]

Yup! Cracked joints.... Or so I'm guessing. I've reflowed these connections at least five times, but ended up desoldering and resoldering the connector to the motherboard and it seems to be holding. Fingers crossed.

Thanks all!!