Motorola 9T1, TS-18 chassis HV supply

[rj26220]

Hello,
Trying to restore above TV have sound but no picture because HV is about 800
volts. 1b3 is ok so is HV osc. 25l6. All components and voltages in HV osc. and HV rect. section check within specs. 1b3 fil. does glow. Adjusted feedback spring on 1b3 but still can't get HV above 800 volts. What am I overlooking?

Rich

[compucat]

I have a Motorola 9VT1 with the same chassis. It is best to replace all the resistors in the HV circuit as well as the wax paper caps. It has been a while since I worked on mine but I believe there are some 1 Meg plus resistors in the HV oscillator and rectifier circuits. These need to be changed. The proper HV for this set should be around 6000V.

[rj26220]

Hello,
Compucat thank you for the response. I have changed quite a few caps and resistors in other parts of the set and replaced the selenium rectifiers with diodes. The horz. osc. output caps. have been changed and it's output seems ok. The parts for the HV section (HV osc. and HV rectifier) have been changed or are ok. I tried to sub the 1b3 with a 1b3/1g3 but discovered, with the lights out, that with the 1g3 the HV section was squegging as I could see the 1g3 filament glowing in tune with the squegging!!!! I'm trying to get another 1b3 just
to see if there's a difference. I know I'm overlooking something but not sure what.

Rich

[Eric H]

Hi Rich, there are something like 4 .005@6000v tubular caps under the chassis and another inside the HV cage I think.

These will have to be changed, I'd bet that's where your HV is going.

These are available through Allied Electronics http://www.alliedelec.com/ or Antique Electronic Supply http://www.tubesandmore.com/

Ultimatly Compucat is right, you'll have to replace every paper and electrolytic cap in this set to make it work right, a pretty easy task on that chassis.

[rj26220]

Hello Eric,
Well I've replaced all of the HV caps and all but 2 in the audio section and have also replaced resistors. My HV probe still shows less than 1kv although since replacing the last few caps I can get a little light on the crt (very little). The hv probe is a Pomona and is good. I can draw maybe an 1/8th inch spark from the plate of the 1b3 but that's all. One thing I've noticed is that I can't use 1b3/1g3 tubes in it as the tv seems to sqegg no matter where I put the feedback spring.
Is that telling me something? Any ideas?

Rich

[rj26220]

Gentlemen,

HV now good enough for raster. Found one last cap that looked real good ohm wise but put a couple thousand volts on it and it was junk. Now going to fight a
vertical linearity issue. Thanks for your help.

Rich