Power Ripple in DEC BA11-K

Hi. I try to get my "new" PDP-11/34a back to live. I did a quick PSU test today with dummy loads. All voltages, LTCL, DCLO and ACLO where OK so I pluged in the logic boards. But the machine does not respond to the knobs on the programmers console. Pressing HLT + CNTRL brings the machine not to halt, but the "Bus Error" LED of the console lights up. Grant continuity cards and NPR jumpers are in place. It looks like I have the wrong bus terminator: There is a M9301-YF at the CPU side and a M930 at the other bus end. It seems I need a M9302 in place of the M930? This would explain the bus error. I took my scope to have a look at the ripple of the voltages. Here is what I got on the second +5 V PSU: X = 0.2 V / div ; Y = 2 ms / div http://www.unixag-kl.fh-kl.de/~jkunz/tmp/5_Volt_Ripple__y=0.2V__x=2ms.jpg X = 0.2 V / div ; Y = 10 us / div http://www.unixag-kl.fh-kl.de/~jkunz/tmp/5_Volt_Ripple__y=0.2V__x=10us.jpg I get similar pictures on all voltages. Both +5 V power bricks (H7441) show similar ripple as well as +15 V and -15 V. There are spikes with up to 1.2 Vpp and it is clearly related to the 50 Hz lines frequency. This doesn't look that healthy. I had a look at the BA11-K power distribution schematic. The two +5 V PSUs are independent and run of different windings of the mains transformer. I am a bit surprised to see about the same fault on all PSUs. I am no SM-PSU expert, so I am now at the point where I have to ask for advice. -- \end{Jochen} \ref{http://www.unixag-kl.fh-kl.de/~jkunz/}