[Findm-Keepm]

'HS5 or 'HV5 get grid current from the horizontal oscillator - make sure your oscillator tube is good. A weak one will mess with the HV regulation. Also check any pf ceramic caps around the grid circuit - part of the integrator, and a leaky one will shunt the pulse to ground, leading to reduced HV regulation, reduced HV, or even no HV.

Be careful measuring voltages - the impressed AC pulse from the flyback is much higher than the DC voltage it's riding on, and even a robust Fluke will crap out - the pulse amplitude will cause the MOV across the input terminals to shunt any excessive voltage, and you'll get squirrelly readings.

Switch to a VTVM ( i used an RCA Senior Volt Ohmyst) and it'll read the DC voltages properly. Stay off the plate(S) of the HV reg tube or you'll surely eat a meter.

Saw the wacky voltages on 20Y1C38 that initially had poor HV regulation ('twas a 220pf 3KV cap....) and later a bunch of ghosting in the video IFs that gave me a fit.