Author Topic: Testing CRT from scope ?  (Read 232 times)

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Offline lordvader88

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Testing CRT from scope ?
« on: July 09, 2019, 01:44:24 am »
I bought a broken vacuum tube oscilloscope scope that was dropped, (turns out the transformer is burnt out too). The CRT was knocked when it dropped, and there's even a little bit of debris of something loose inside.

 Actually the whole PCB cracked in have and 2-3 resistors. I fixed all that, then discovered the trans was shorting.

I have DMM, LCR/ESR meter, scopes. Is there any low voltage tests I can try to determine the state of it ? I have various HV sources, but I'm not messing with any of that yet
« Last Edit: July 09, 2019, 01:47:53 am by lordvader88 »

Offline Ian.M

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Re: Testing CRT from scope ?
« Reply #1 on: July 09, 2019, 02:25:42 am »
Not really.  The only things you can check for with low voltage testing is if the filament is intact or if there are any obvious inter-electrode shorts.  It wont pick up if the electron gun has been knocked out of alignment, or damage or distortion affecting to the deflection plates or to the acceleration gauze if the tube is a high sensitivity deflection one.  Even if you were prepared to apply the correct voltages to the gun and final anode, to check it produces a focusable beam, unless you have a full deflection system + something to drive it to produce a grid pattern, you wouldn't be able to test for geometry errors.

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