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Old 09-12-2017, 01:06 PM
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DavGoodlin DavGoodlin is offline
Motorola Minion
 
Join Date: Aug 2011
Location: near Strasburg PA
Posts: 3,400
Quote:
Originally Posted by old_coot88 View Post
What voltage do you get on G2 with the tube removed?
I got the full 405 vdc on G2 when HOT is pulled. It turns out the HO tube was dead, when my tester merely showed it to be slightly weak I need a good tester BUT I do have plenty of tubes.

I put a slightly-used GE 6LQ6 in and got no HV but the plate got full red as the cathode current climbed rapidly to 430 ma!! I quick measured the screen G2, and it was up to 175, normally 145.

Pulled plate cap and disconnected screen resistor again, measured the horizontal drive, -55 vdc and a 200 voly p-p sawtooth on the grid G1. No issue there.

I'm fixing to condemn the flyback*, seeing this dreadful symptom on old color RCA's before, and using a flyback ring-tester should confirm. The fly's DC resistance may also give a clue.
Ideas?

* Owner has a spare fly, no hunting needed
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