Don,
Thanks for heads up on MSIB. After doing the caps, caps, caps mantra to no avail. I was in doubt that the ESR readings of the original caps were that far south to result in what I was seeing, and they weren't as there was no change after replacing. Still couldn't see the 70900A on the A-Map. The caps were tested at 100KHz and showed remarkably well for their age. I f you have a good ESR meter believe the instrument. I have not replaced the 2 vertical electrolytics and need to. Wondering if these have problematic failure rates?
I re-read your post and started exploring the MSIB and found that cycling the NORMAL-TEST dip switches, with power on resets, permitted recognition of the 70900A. This showed that, for whatever reason yet to be determined, the MSIB was being corrupted when in NORMAL and going to TEST freed the MSIB enough to see the 70900A.??
I then returned switches to NORMAL and the screen showed spectrum...well, kind of...errors logged and ERR LED and YTO UNLOCK on...
Doing an Error Report produced...
After running for a while (warmed up?) or switch-diddling the errors reduced and listed only these 3... I need to do a cold restart, Error Report, hands off letting warm up, do another Error Report and see if some of the errors cleared with warmup.
The switch-diddling referred to above was the result of changing start/stop/span settings...etc. Th system while allowing keypad entries was somewhat sluggish in responding. Furthermore, entries of reduced START/STOP frequencies (MHZ) required multiple tries as system would resort to GHZ previously set, which may be normal if SPAN settings were in GHZ and in effect. All this was done in an attempt to see 300MHZ onboard cal source; this failed.
?
BOTTOM LINE
Some success but believe I've still may have a PS issue as the cause for the blown fuse is unknown would not have been caused by any of the caps replaced. Looking at the Errors the UNLOCK and UNLEVELED errors may point again to power problems.?
The saga continues...
