help needed: problem with UNIBUS access on my PDP-11/70 - test-drb@ccmp.vtda.org

12 Jul 2002

Ok, many tips to check on this weekend.

...
  Did you catch your washing machine;-) Just curious
what the washing
 machine has to do with checking your power supply voltage? The
 voltages you want to check are the DC +5, +15, -15, etc. Also you
 ought to check the ACLO and DCLO signals. I had a case where the
 regulator board in my lower h7420a was asserting ACLO when in fact
 all of the voltages were fine. 
I meant the power supply voltages at the secundary side of course.
As Andreas says, when the washing machine runs, turning on any big
PDP-11 blows the fuse. I have to reset all clock radios and the clock
on the microwave oven.

I definitely will check the DCLO and ACLO signals!
I will use the scope also to check the +5V lines for any ripple.

[.. test with diagnostic PROM on M9312 ..]

...
  It's not clear to me _when_ PAUSE goes on here. Do
you mean that when
 you try to run the code from the boot ROM (i.e. when you press START)
 then the PAUSE LED goes on? Or do you mean that the code runs correctly
 but that even after running it you get a PAUSE when trying to access
 the DL11-W? 
To clear things on the question from Tony, when I push the START button
the PAUSE led goes on immediately. I will not get that far that I can
try to access to the DL11-W again.
I will swap the M9302 at the end of the backplane (it is there, I just
forgot to mention it) with an M930.

All slots that need a grant card according to the Field Maintenance
Print Set (FMPS) have one installed. The FMPS shows G727 flip chips for
one slot of the 4 slots per MASSBUS interface that not installed, and
all UNIBUS slots at the end of the backplane.
I had the same experience as Ethan did.
When I removed the TU80 interface from my 11/34C the system hung.
I inserted a double grant card G7273 and all was fine again.

Have I nice weekend,
- Henk.