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Hey Gary,

I've never been inside one of those, so I don't know much about them -
alas. Your problems do sound very much like what one gentleman went through
on the EEVBlog <
>
and apparently fixed by replacing the acquisition RAM.
Unfortunately there isn't much information available about these that I'm
aware of. From reading between the lines of the service manual <
>, my guess would
be that these scopes are CCD based like the 2430/2440 scopes, so you may be
able to glean a lot of background from their service manuals.

The CCD-based scopes have two acquisition modes, where "fast" one stores
the entire acquisition in the CCD, and reads it out on a trigger event. The
"slow" mode is only used in roll (IIRC), and it's possible that the
acquisition memory is out of the loop there. Have you tried the roll mode
with a suitably slow signal?

Do you have a second scope to diagnose the sick one?
When you say "won't trigger", you mean that the trigger light does not turn
on, or the "signal" rolls?
Note that if the acquisition system is out, then autoset won't work, so
you'll have to fiddle with the triggering controls to get sensible
settings. Also if the sample memory is out, the "signal" will roll at most
or all time base settings...
Have you tried the ext trigger input, does that work?

Note that by your description, this very much could be dodgy acquisition
RAM, except that the triggering is analog, and should be working even if
the acquisition RAM is barfed - hence the suggestion to give the triggering
controls a really through fiddle.
AC coupled input, with NORMAL trigger at mid-level should work, if any
triggering works.

Siggi