1967 Admiral Horizontal Section Troubles

[N9ZQA]

Hi all -

Looking for some help on my 1967 Admiral - the one with the arcing damper tube. The tube snapped once or twice and the picture returned to normal. As soon as I saw that, I turned the power off and unplugged the set. I've since ordered a tube and have finally gotten back around to messing with the set.

I replaced the damper, fired it up, and although I didn't get any arcing, I also didn't get any high voltage - but I did get a nice red glow from the plate of the 6KD6! Pulled the plug immediately and have been doing some troubleshooting with the horizontal output tube removed.

My determination so far is that the horizontal oscillator isn't running; I'm seeing .3 to .4VDC at pin 5 of the 6KD6 rather than the -60VDC the service manual mentions. I've attached a scan from the service manual detailing the horizontal section - maybe this will help.

I replaced a few of the resistors in the oscillator section; most were at the high end of +10% if not a little over; a couple were 1.5x their rated value. I only replaced 1/2 watt resistors as that was all I had on hand.

I haven't replaced any capacitors yet (except for the 20uF electrolytic) and I'm trying to learn from this rather than just shotgunning the whole thing.

Measuring voltages at the pins of the horizontal oscillator gave me the following values:

Pin 1- control plate +240 VDC
Pin 2- oscillator grid -28VDC
Pin 3- oscillator screen +233VDC
Pin 4- heater +6.3VDC
pin 5- heater 0VDC
pin 6- oscillator plate +174VDC
pin 7- oscillator cathode 0VDC
pin 8- control cathode +8.2VDC
pin 9- control grid -10mVDC

I'd like to puzzle this out and ensure that the circuit is functioning correctly before popping another HO tube in and trying it out.

Now for the questions:

1) I'm assuming that the two plate voltages are elevated over what's on the schematic since the tube isn't conducting (oscillator grid is at -28V and the control cathode is 8V above the control grid) - correct?

2) Can somebody shed some light on how this circuit works? I understand so far that it's a free-running oscillator that locks to the pulses from the sync separator, but what acts as the feedback path - is it the horizontal hold control?

2a) In light of question 1, is there something that would 'kick' this circuit to get it started?

3) Are there any areas that I should focus on especially - and if so, what would I be looking for?

Thanks in advance,

Jim