11/70 problems...

From: Johnny Billquist <bqt_at_update.uu.se>
Date: Fri Jul 12 12:41:01 2002

[...]

> Unfortunately, this installed PSU does not solve the problem.
> I still have the PAUSE led on with any access to 1777756x (read/write).

[...]

> 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.

Time for a reality check now! The machine runs! DCLO and ACLO is not the
problem.
What is the problem is a total hang when trying to access the DL11. The
question is if he can access the I/O page at all. I haven't heard any
confirmation if it is possible to read from the bootstrap code
locations. They are also in the I/O page, and thus is a very interesting
test.

PAUSE goes on when you start boot, but that don't tell us enough. The boot
roms don't access the console, so we atleast know that the DL11 isn't the
only problem. I suspect you have problems accessing the I/O page in
general. But can you access the MMU registers, and other processor
registers at the I/O page?

And still, NPR might be the problem. If I remember correctly, a broken NPR
might show up just like this. The same goes for the BG lines. Remove and
reinsert the grant cards, check the I/O page more.
You have access to memory, and can run programs, so let's skip the stuff
that we know is working correctly.

        Johnny

Johnny Billquist || "I'm on a bus
                                  || on a psychedelic trip
email: bqt_at_update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
Received on Fri Jul 12 2002 - 12:41:01 BST