1979 GTE Sylvania GT Matic CX9164W chassis E24-3

[JohnCT]

Originally Posted by pac.attack76

Ok I pulled one leg loose and put a lead on each end and got what you see on meter at that setting.

I believe that means the diode is not shorted on your meter.

Install the diode back into the circuit, remount the horiz output, and retest the metal case of the transistor to ground to make sure the short is still there. Sometimes it's best to backtrack and start over.

If the short is there between chassis ground and the metal case of the output, the two most likely culprits at this point are the retrace capacitor or a puncture in the mica insulator between the horiz output and the chassis (we tested the output before so we'll assume for the moment it's OK).

If the short is now gone, remove and inspect the mica insulator under the horiz output transistor - these were very thin and prone to cracking or puncturing. Sometimes just resetting them with new heat sink compound clears a short, but because there's a 1500 volt pulse on it, it will arc through if you attempt to run it. If the mica insulator is damaged, replace it and you should be good to go.

But if you install the output and get a low ohm short to chassis ground again, remove the two mounting screws of the horiz output and retest. If the short is still there, either the output or the mica insulator is bad. If the short disappears when the screws are removed, the output and mica are good.

*Anything* that is connected to the B+ line and goes to ground is a suspect, including the main B+ filter, but since the tripler had what appears to be a puncture, we start closest to the HV and work back.

Report back what you find with your meter.

John