Dead SCSI bus anomaly on old Mac's

[Outlander]

Ok, so, I'd like to bring this subject back up again. So far now, my Macintosh Plus, SE, Macintosh II, and now my Macintosh IIx are affected. What's happening is that one day these macs just start refusing to boot from an external SCSI HD or CD-ROM. Re-capping the logicboard does not help with this issue either. There has got to be another component on the logicboard that ages like capacitors do and fails in time, I just havent figured out what it is yet. Have any of you out there been effected by this problem?

 

[techknight]

I assume your using the same SCSI devices between all the machines? Maybe its the SCSI devices you have. Cables, Terminator, Etc? 

Usually in the state of troubleshooting, its rare that many devices fail at the same time doing the same thing, and the single device used between them is fine...