ssj152 at charter.net
Sat Oct 14 21:14:07 CDT 2006
Well, this is my first post to the list in quite a while; most of you may
not even remember me... but I have been lurking.
Now I have a problem I need help with. I have a PDT-11/150HC, the dual drive
model with 32KW and the 3 extra serial ports. It had been working fine, up
through last year, when I stored it.
I was working on another project, building a PDP-11/53 from a DECServer 550
(like Jonathan Engdahl's) when I needed to copy some floppies. I brought out
the trusty old PDT, and of course, it wouldn't work.
I am using a VT420 with DECConnect wire and shells to talk to the PDT. The
VT and wires are all known good, tested with other equipment.
What happens is that when I turn the PDT on and type the 2 "@" characters to
set the baud rate (4800), the #2 led properly goes out, the RUN led comes
on, but NOTHING comes back to the terminal. Thinking that I needed a NULL
MODEM in the cable, I put a MMJ crossover connector block between the
terminal and the PDT. Strangely, I had exactly the same results - nothing
out on the monitor - with TX and RX swapped how the heck does this happen?
As I recall, the usual response is something like "Press B to Boot". In any
event, pressing "B" does nothing either.
I have performed the self test with the lid off and modules elevated and the
result was that the first 4 LED's on the Intelligence Module came on.
This is result #17, indicating that either the DISK Controller Module or
Cable G1 has failed and need to be replaced - impossible, at least in the
case of the Disk Module. Besides, what does this have to do with no response
on the terminal?
My next step is to test the power supply and trace power to the various
modules, as per the Mini-Maintenance manual. I'm hoping that someone on the
list is more familiar with the PDT and can offer useful suggestions that
might shorten an exhaustive troubleshooting effort - I'm not really up to
I have as resources 3 books, 1) The PDT 11/150 User Guide (EK-PT150UG-001),
2) The PDT 11/150 Installation Guide (EK-PT150-IN-002), and 3) The PDT
11/150 Mini-Maintenance Hardware Guide (EK-PT150-J1-002). I would very much
like to get a copy of EK-PT150-TM, the Technical manual, in print or PDF
I also have the usual DVM, a Tektronix 2215 dual channel scope, and the
memories of being an electronics technician (with a radiotelephone license)
during my late 20's, a lifetime ago. I spent the last 20 years of my
so-called career as a systems programmer and am now retired.
Can someone that knows about the PDT assist me? All useful input
Ssj152 AT charter DOT net
Old man, Old hobby
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