13 Nov
2006
13 Nov
'06
11:43 a.m.
Gooijen, Henk wrote:
Don wrote:
I was thinking
more along the lines of excess noise/ripple on a
supply, not that it had completely failed. If the supplies (+/-15V,
+/-12V, +5V) are out of whack the DC OK led will go off, but if one
of them (like 5V) is noisy, it could result in intermittent logic
operation but still indicate DC OK.
What I'd do at this point is verify all the
P/S voltages are
within spec, and then pull all the boards that are not
necessary (FPU, CACHE, and any UNIBUS I/O) for basic system
operation. Run with just the base CPU and a memory card.
Regarding reason #3, the System Tech manual says on page 3-10
that the CPU only needs the +5.1V power supply. I was thinking
that if I get anything on the VT100, that +5.1V must be present.
So, I did not check that! BTW, I wonder if the table 3-7 is
correct. Doesn't the CIM (M7090) need +/- 12 or 15 V. for the
RS-232 signals? Or the MFM, I'd need to check the schematics. I did try with FPU removed, and I did read that you
can run the
11/44 without CACHE. I will try that too this evening.
And running without UBI didn't even occur to me! The memory has
dedicated slots, so it is not accessed through the UBI module?
Maybe I should have
been clearer; I meant UNIBUS I/O modules (like
a disk controller) not the UBI module. AFAIK you can only remove the
CIS set, the FPP, and the CACHE module and still have the CPU be in
a runnable condition. The UBI module (M7098?) is not optional.
Don