Oscilloscope Calibration or Repair?

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Gold

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Jun 23, 2004
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I have a Tek TAS 465.  It was an evil bay special. The display has always had a blinking quality to it. In the photo you can see it’s not a crisp trace.  There are light and dark parts.

Then today I got that superimposed low frequency wave. The tone is 10K. I was driving myself nuts trying to figure out what i was seeing. I then removed the DUT and it was still there. I power cycled the scope and it went away.

The text on the display also looks wobbly.

Do you think if I get the scope calibrated it will take care of these display issues or does it need to be looked at in more detail. The calibration houses don’t do “restoration “.
 

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Gold

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Thanks! It looks like he is dealing with the same sort of display problems I'm having.
 

Whoops

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Hi Paul,
try out the EEV blog forum, a lot of Oscilloscope gurus out there and also a lot of threads on that specific model.
I think you will find the solution there or can get good help in solving it
 

Gold

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I’m a little embarrassed to say but power cycling  the scope fixed the problem.
 

cyrano

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Sep 6, 2010
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I had a very similar situation a while ago. 125 kHz, not 10 kHz. Spent days looking for the culprit.

It wasn't until I moved the equipment that I realised it was only present in that one spot in the room. Turned out the culprit was a VFD driving the big sewer pumps under the road.

I've moved my equipment to another spot in the room. No more problems.

It made me curious and I found two other spots in the house where the same interference is present. Both are 3-phase circuits that are no longer used. The first one, however, has not 3-phase circuit near. At least, as far as I can tell.

Even my Fluke DMM behaved strange in that spot. Showing up to 6-7 volts on the DC range, with the leads attached to nothing.
 
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