AAACK (blush) HELP HELP (was: HD2 upgrade...) and power supply question

Kevin O'Gorman kevin at kosman.UUCP
Thu Mar 28 13:56:27 AEST 1991

I got impatient about some info on the HD2 upgrade, and tried running as just
a P5.1 upgrade (replaced the PAL into the socket).  This machine now appears
pretty dead.

The symptom is what I have come to call the "rectangular spiderweb" on the
screen, no disk activity, no marching blocks, no evidence of CPU activity
at all.  The screen has a repetetive pattern probably caused by alternating
32-bit words of all 1's and all 0's -- fine rectangular tracery.  Either this
is the pattern that the video ram defaults to, or is caused by an early step
in the boot roms and the fact that a video raster is an odd number of 32-bit
words.  The green LED is on solid, the others off.

Well, I probably did it to myself, but I could sure use some help figuring
out just exactly what I did....

I have tried looking at the power supply, which was the culprit the last time
I saw this pattern.  I had -12.03, +5.25 and +12.03.  I have read that 12.40
is a bit more like it and tried tweaking.  On two different supplies I can
tweak +12 and +5, but -12 is rock solid no matter what I do to the pot.
Is that pot for real?  Should I be able to adjust -12?

Anyway, this is not solving my problem.  Please, anyone have advice for
debugging a HD2 upgrade when your tools are a soldering station and a digital
multimeter and a couple of space power supplies?

Fortunately, this machine is my (very) old 7300 Attilla, who has been through
the wars since I bought him in April of '85 (yeah, just two weeks after the
product announcement) with 512K and a 10-MB disk (what good was that, you ask?
I used it as a word processor (to make money), and to teach me UNIX and C).
I still have Ghengis, a fire-sale 3b1, which I will upgrade if I ever get
back my confidence.
fire-sale 3b1.
Kevin O'Gorman ( kevin at kosman.UUCP, kevin%kosman.uucp at )
voice: 805-984-8042 Vital Computer Systems, 5115 Beachcomber, Oxnard, CA  93035
Non-Disclaimer: my boss is me, and he stands behind everything I say.

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