I have rebuilt an HP 180D oscilloscope (rack version) into a bench
version. Everything seems to be working ok, except that now the
back sweep is also visible. I did not have this scope for a very
long time, but I believe that in its original layout (wide) the
back sweep not visible and thus suppressed.

It might be that because the plug to the plug-ins was moved and
twisted (but no wire was actually unsoldered), there is somewhere
a bad or broken connection, although I checked most relevant ones.
I am not an expert in electronics at all, but would like to know
which part of the scope is actually responsible for suppressing this
back sweep. I suppose it is somewhere in the gate amplifier and
that it may be to do with the "unblanking" or "blanking" signals.

Any help or suggestion would be appreciated.

--
Charles Stroom
email: charles at no-spam.stremen.xs4all.nl (remove the "no-spam.")