HP27 Restoration (Lots of Corrosion)

[calc-calcs]

Here are some scope screen shots of the data lines: clocks Ø1 and Ø2, ISA and DATA. Also the signal at the timing inductor of the ACT, frequency seems to be 707KHz, which kind of rings a bell from when I was working on the HP25, so it should be correct. ISA buss is basically at the same frequency of the LC oscillator, only higher in amplitude, but exactly the same waveform shape.

I did verify that all data was present on all IC pins where it should be, and previously also tested continuity between all those points.

As can be seen there is a 1.4uS shift between the Ø1 and Ø2 which I assume to be on spec.

I did not see much if any activity on the SYNC or RCD lines. Should there be continuous activity on these lines?

Anything else I should be looking at?