Power Ripple in DEC BA11-K

On Wed, 27 Jul 2011 21:55:37 +0100 Pete Turnbull <pete at dunnington.plus.com> wrote: I scoped the voltages again with the probe grond clip connected today. I still get some noise, but this may be related to the ground problems of the scope and to the GND wires carrying current. So I am tempted to say the supply voltages are OK. Same for DCLO and ACLO. All empty slots have G727A grant cards. BRn / BGn connections facing away from the CPU. The NPR / NPG wires are still in place on the backplane, but in slot 8. This slot has a double with, non-DEC grant card that connets NPR and NPG in addition to BRn / BGn. I measured all NPR / NPG connections and they are shortened as expected. This is the Unibus configuration: 1: ABCDFE: M8266 2: ABCDEF: M8265 3: AB: M9301-YF CDEF: M7859 4: ABCDEF: RAM, 256 kB 5: ABC: empty D: M727A EF: empty 6: AB: empty CDEF: M7856 7: ABC: empty D: M727A EF: empty 8: AB: empty CD: Grant Card EF: empty 9: AB: M930 C: empty D: M727A EF: empty Still: Pressing CNTRL + HLT at the programmers console lights up the "Bus Error" LED a second later while the "Run" LED is still lit. I reconfigured the DL11-W for 9600 8n1 and soldered a new console cable. But I don't get anything from the serial console. Any ideas what to check next? -- \end{Jochen} \ref{http://www.unixag-kl.fh-kl.de/~jkunz/}