Delay Line Issues

[Jon1967us]

This CTC16 has recently displayed symptoms of delay line failure. The even spaced ringing is a sure sign of ringing in the line, as verified by shorting the line (and disconnecting its ground lead)

Schematic




Shorted:



I've since replaced the original DL with one from a spare CTC10 chassis, but to no avail. The ringing is still there. Very odd.

Now, I'm thinking an out of tolerance resistor could be the cause of the issue.

I measure 45-48V on the plate of V4B (should be 35), so I'm wondering if this excess voltage is driving the DL too hard. The excess voltage perhaps being a symptom of R62 dropping out of tolerance? Or could it be R63, 64 drifting? Hmm