On 3/6/2021 5:21 PM, Thierry Delaitre via groups.io wrote:
When using beam finder, I can see a single vertical bar of 3cm height on the two thirds of the right hand side of the screenWhich points back at the plugin, saying that the trace is deflected all the way to the right. Normal location for an inactive trace is the left side of the screen.
It would have been nice to feed in a signal and bypass the sweep generator.
Not sure that you should be seeing a horizontal bar, but that's more or less moot for now.
Ok, what I suspect is that one of two things can be going on.
1) the sweep is still active, but the driver transistor that couples to the horizontal amplifier is open/leaky, or you have a capacitor that is making that transistor behave like that, thermally related. Upsets the bias on that output stage and I think it will be turning off.
if the sweep pickoff is in the plugin, then look at that. If not, then use a separate scope to see what is hung up. A can of freeze spray may reverse the symptoms long enough for you to figure out what part is bad.
2) the sweep itself is not working, however, the triggered light indicates (to me) that the sweep is working, since I think it's frequently driven by the sweep gate itself.
suggestion: remove side panel from scope, remove cover from plugin, insert into far right slot, and use another scope to see what's going on.
Now, given that you do have a 7000 series scope (you'll like this part), instead of a separate scope:
put your working sweep plugin in slot #3, put the scope on chopped horizontal mode, and use the working vertical channel and sweep to debug the faulty one.