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@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 >
