Quote:
Originally Posted by old_coot88
Umm.. considering the rarity and irreplacibility of that flyback, and since you haven't already run it for more than a few seconds in the fault state, please hold off on this test.
Rather (after replacing C61), do the 'air arc' test again. It will confirm whether the fly's putting out without loading it down.
Now, if the fly's putting out, install the 1X2 with the plate cap connected, and remove the doorknob. This will avoid loading the flyback (in case the tube is gassy). If the tube is good, the HV should come up and light the CRT. If the 1X2 is gassy, it may fry the 470K resistor (R89) in series with the HV lead. R89 is thus "sacrificial" and takes the load otherwise borne by the flyback with a gassy 1X2. Much easier to replace a resistor than the flyback.
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Ok tests ran, here are the results. Fly is air arcing away. Door knob removed and HV going right to the picture tube. I want to rewind a bit to before. Miniman82 first suggested removing the doorknob cap and firing the set up to see if that solved the problem. The doorknob cap is secured to the base of the rectifier through a screw in the base to the top of the cap. On my first test I removed the screw. On this test I removed the screw and MADE SURE that the base was not in contact with the cap at all. Different result. The tube did not glow or crackle at all this time. Unfortunately a new arc has developed. It is between the flyback and the filament winding for the rectifier. I've indicated where it is with the white arrows below. It is not constant, and only happened 8 or so times total with all the tests I have done tonight. It seems that Miniman82 might have put his money in the right place and the doorknob is toast. It is not shorted to ground but it could be toast. A new doorknob might be the answer. I don't know what to do about the sparking flyback though.
