Tektronix plugin 7A26 injured

[Opcom]

Unfortunately a 7A26 plugin got damaged or just died today. The scope frame is a 7904. (pics show what these look like)

We were working on a high voltage DC coupled tube circuit - and I really believe the signal was within the plugin's spec.
A 15 meg resistor was attached in series at the end of the X10 probe on the 5V scale (50V/cm) to give X5 multiplier adjustable to 250V/cm.
The plugin is rated  500V p-p, 250VDC.
A 78KHz sine wave of 100V p-p was being measured on a DC rail of about +200V.

so what happened? I hope it's minor, but also have no extender card to work on these.

The channel in question quit and no longer passes the sync, so maybe an early stage or on the attenuator board. The other CH works. I think the V position still works as the traces stayed where they were but I ought go back and recheck everything.

It's an old system but it is sure useful in every way, and there's another just like it (7904A) and a stack of other plugins so I would like to fix it. Anyone have a extension card or maybe had worked on this kind of thing?

[n2bc]

Great group of very knowledgeable folks on this YAHOO reflector:

https://beta.groups.yahoo.com/neo/groups/TekScopes/info

[Opcom]

Thanks!