Oscilloscope - Tektronix 2336 YA - Strange ringing (between 100-200 MHz) problem

[felixd]

Hello.

I'm seeing strange thing on my Tektronix 2336 YA. Since I've bought it oscilloscope is triggered by a pulse that is coming from "nowhere". It appears randomly in every 30s - 2 minutes.

This pulse is seen on each channel (on AC/DC/GND mode), probes connected/disconnected. This pulse is also seen on probe compensation signal. This is how I've managed to record it using 2nd oscilloscope. Pulse/ ringing  frequency is between 100-200 MHz.

This pulse runs trigger.

I've also accidentally recorder it on below video (0:36 second)

Wiertolot - Silnik EMAX GT2215

I've recorder this pulse also on probe compensation signal:






Any ideas why this pulse appears? How can it be fixed? What to check ? ;]

Thanks for replaying

[Niklas]

Perhaps it is not related to the oscilloscope at all. It might be something in the same building that draws a lot of power and is switched on or off periodically. Perhaps try another power outlet and see if the problem disappears?

[felixd]

I've connected it to UPS.
Same thing.

My digital scope is not affected.
Can it be dirt inside old scope + very high voltage? Maybe that's a problem.

[PA0PBZ]

It almost looks like a burst of RF, but it seems a bit short to be useful. Any RF transmitters near that could do this?

[xygor]

It looks like there might be an intermittent arc inside the scope.  Open the case, turn off the lights, look, listen.

[felixd]

It looks like there might be an intermittent arc inside the scope.  Open the case, turn off the lights, look, listen.

I was talking yesterday with people from Poland. They told me that this might be the problem.
I'll check that tomorrow.

[felixd]

Lot of time since my last post. The problem is with arc's. I can hear them, but I'm not able to see them

Today I have some time to dig inside my oscilloscope.