Flaky SE FDHD

[IIfx]

Well, I could never figure out why this mac never liked to work right. It enjoys crashing.

The symptoms are locking up at random, or if you leave it idle it and move the mouse the system will crash with a bomb error or total lock up.

Sometimes I can install Mac OS in time before it freezes, sometimes it crashes curring setup. Its not the hard drive or floppy drive, I tested those in a different mac and they are fine. After a quick inspection of the logic board, I saw no capacitors leaking, no PRAM battery leaking, and no IC damage.

There are no expansion cards installed in the mac, and I tried pulling out 1/2 of the RAM just to make sure.

:?: Any help would be appreciated.

 

[IIfx]

Anyone? I cant figure this out :?:

 

[beachycove]

I can think of two immediate possibilities:

1. "SCSI Voodoo" or hard drive termination sounds likely. In what machine did you test the drive and how was termination set when it was in there? Was it, for instance, the only drive in the machine in question or was it in a chain on the same SCSI bus when tested working?

2. Bad RAM. Replace with spares if possible for diagnostic purposes.

 

[IIfx]

Ok. I started it up to begin fixing, and I notice 2 faint jumping lines on the display. I refer to the dead mac scrolls, and aparently its the analog board being out of adjustment. Before I was going to do any tinkering, I decide to try to boot from a System 6 disk, and the instant I put the disk in the drive, the mac resets. The good disk is rejected by the SE each time.

I think I am going to remove the SCSI hard disk and see what happens.

News: On the removal of the HD, it boots from the System 6.0.8 floppy. However while typing in TeachText, I heard faint noises coming from the mac each time I pressed a key. I think this indicates a larger overall problem, but I am not sure.

Some other details: It was MFD in 1989 in the Fremont Factory. Its a pretty young SE.

 

[IIfx]

Ok, I left it idle for 5 minutes with TeachText open. I come back to type and the mac is 100% locked up. So its not the SCSI HD that tests fine in other macs. (As the only drive in a IIcx)

Edit: I left it idle once again, moved the mouse, and the screen went all garbled and the mac emitted a horrifying buzzing noise, then promptly reset itself as if nothing even happened.