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Old 29th Feb 2020, 8:20 pm   #7
Sideband
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Join Date: Oct 2003
Location: Croydon, Surrey, UK.
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Default Re: Pye VT4 - no EHT

Quote:
Originally Posted by Vectamart View Post
I have a few of these in my collection and decided earlier today to have another go at getting this particular one working.
You don't say if the others in your collection are working. If at least one is, why not do a side by side comparison. You can check voltages and scope waveforms between the non-working and working sets.

I used to do that when I was in the trade and had an odd set and wasn't sure what was going on.

If you have a healthy spark at the input but no output, it suggests to me that there is plenty of line drive but the output is being damped. Try unplugging the EHT lead from the tube, insulate it and place it well out of the way of anything else and see if you then get a healthy spark from the cathode. Does the TV have an EHT smoothing cap (visconol) or does the CRT have an aquadag coating? If the former, it could be the visconol.

However John (HCS) has a good point about the scan coils. If the line scan coils are O/C this can cause the exact effect you have.
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Last edited by Sideband; 29th Feb 2020 at 8:29 pm.
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