Hi Everyone,
This is my first and only piece of sampling equipment, and I can't get it
to work. What I get is a flat trace with just some minor noise on it.
I connected the same signal (10MHz <1Vpp) to both heads inputs just for
test (let's just ignore this blasphemy for now since both inputs are 50Ohm,
and I don't have a S-6). S-53 triggers, I can see the tiny short trigger
pulses from the front connector on another scope. The trace appears only
after S-53 triggers, so I'd say that part works. DC offset also works, and
Volt/div setting increases noise on the trace with higher sensitivity, so I
figure the vertical block of the 7S12 is OK.
So the main suspect is the S-4, but I have no idea how to troubleshoot it.
I can see the tiny sampling pulses being fed to it by 7S12, but nothing
"notable" on the preamp output on pin 4. The manual says not to test the
sampling bridge diodes using an ohmmeter, but a curve tracer. How could an
ohmmeter (actually DMM, <1mA test current) be more destructive to these
diodes than a curve tracer? (provided that the test is carried out using
forward bias only). How to test the snap-diode? Is there any other
extra-sensitive component I should be aware of?
Best Regards and thanks,
Nenad
