Mystery IIsi that chimes, but has no video, and won't boot!

[franklyn]

I also had the problem that the start sound was fine but the computer didn't bring up a picture onto the monitor and didn't boot. The reason was bad contacts (oxidized) on the video controller chip. New/re-soldered and now everything is good ...


On other computer systems there are diagnostic modules and a null modem serial connection to another computer with a terminal program. Is there something like this for the Macintosh 68k series?

 

[Garrett B]

I see some corrosion near the power connector as well.

Checked this as well - good continuity just missing some solder mask is all.

 

[Garrett B]

I also had the problem that the start sound was fine but the computer didn't bring up a picture onto the monitor and didn't boot. The reason was bad contacts (oxidized) on the video controller chip. New/re-soldered and now everything is good ...


On other computer systems there are diagnostic modules and a null modem serial connection to another computer with a terminal program. Is there something like this for the Macintosh 68k series?

When you say "video controller chip" you're talking about the RBV chip at UA3?

 

[franklyn]

Video are UA2 (RamDAC) and UA3 (Video Chip) I think ...

 

[Garrett B]

On other computer systems there are diagnostic modules and a null modem serial connection to another computer with a terminal program. Is there something like this for the Macintosh 68k series?

You bring up a good point here. I've done some serial diagnostic work on a Portable but didn't even think to try the IIsi. I know it's supported - just need to figure out syntax for the right tests to run. Unfortunately a lot of this isn't super well documented. I'll post back though when I have a chance to get serial set up. That is, if serial is working. Fingers crossed!

 

[corbinq27]

I've got a IIsi that just started doing this after I recapped it. ugh. Honestly I did also do an isopropyl bath as well. I wonder if I got some corrosion slurry to form under a chip in the process.

Curious how this is going for you?