I¡¯ve never looked at these signals, but to my understanding, the readout
board asserts /ROR when it wants to display dots. The display sequencer,
however, gates access to the trace through the /ROA signal. I¡¯d start by
looking at those two, comparing between good and bad boards. Note that the
readout is stealing the trace, and if this is not random to the sweep, you
may be able to observe the stealing as it occurs at the same spot during
consecutive sweeps.
If this is happening in auto trigger mode without trigger, try whether you
still see it during triggered sweeps. See if holdoff changes the problem at
all.
?ann f?s., 25. mar. 2022 kl. 18:58 skrifa?i Dr. Bernd Burfeindt via
groups.io <femtocam@...>:
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Hi,
with the time-base equal or slower than 1ms/scale I noticed "blank outs"
on the trace when I turned on the readout. The blank out are about 1mm in
length at the same horizontal position where the text would appear. I can
fix this issue when I replace the A5 board from my second scope. So the
issue must come from the A5 board.
I am requesting help to repair the A5 board - which I had fixed for leaky
capacitor. PCB traced looks Ok and I replaced corroded resistor etc.
Calibration was done as well. I read the theory of operation but I could
not come up with a good trouble shooting plan. Maybe some does not switch
fast enough.
Does anyone has a good idea to look for?
Bernd
