Looking for DEC M7264-CB Troubleshooting Documentation

Mister PDP vintagecomputersmn at gmail.com
Thu May 9 13:35:51 CDT 2019

I was referring to both the ODT prompt and the run light. I get nothing on
the console and the “Run” light does not come on when the switch is toggled.

On Thu, May 9, 2019 at 12:41 PM Noel Chiappa via cctalk <
cctalk at classiccmp.org> wrote:

>     > From: Mister PDP
>     > I was wondering if any in depth troubleshooting material existed
> online
> I am not aware of any; I would be glad to be corrected. Unlike the early
> gneration of UNIBUS CPU's, these generally weren't intended for internal
> fault analysis and repair - module swapping and replacement was the
> intended approach.
> The LSI-11 manual (EK-LSI11-TM-003) has a tiny bit of detail on how the
> CPU board works (pp. 4-3 - 4-13), it's probably worth reading that before
> diving into the CPU board internals.
> Things I'd check to start with - all the power voltages, and then the
> clocks.
> If those are all OK... BTW, for any serious fault analysis on these things,
> you'll need a 'scope/logic analyzer.
>     > When powered on, the CPU does not respond to the Run/Halt switch
> either
>     > on the front panel or via the console.
> When you say 'does not respond', what's the symptom? Is the console ODT not
> running (which could have any number of causes)? The whole system has to be
> more or less running for ODT to work. I'd start elsewhere - e.g. does your
> mounting box have the 'run' light? (It's driven by an output of the CPU
> card.) Does that display any activity?
> Time to look at e.g. BSYNC, etc to see if the CPU is trying to read/write
> the
> console registers.
>         Noel

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