Starting a Restoration on a 1951 RCA 7T111B

[Notimetolooz]

The HV probe could be somewhat inaccurate. None the less it is a good bet the HV in the set is too low.

Could be that the HV is being loaded down by leakage.
However the other voltages in the horizontal sweep circuit should be checked.

Try disconnecting the HV lead at the CRT and insulate it by putting the end in a jar. Then measure the voltage on the doorknob cap.

[Aperna1985]

Originally Posted by Notimetolooz

The HV probe could be somewhat inaccurate. None the less it is a good bet the HV in the set is too low.

Could be that the HV is being loaded down by leakage.
However the other voltages in the horizontal sweep circuit should be checked.

Try disconnecting the HV lead at the CRT and insulate it by putting the end in a jar. Then measure the voltage on the doorknob cap.

That's actually what I did and got my 4k volts

[Notimetolooz]

OK.
Well the doorknob might be bad, it happens. They are a little tough to find so it would be good to find the problem was somewhere else.
It could be the HV rectifier. The filament glow is hard to see.
Do you know if the horizontal frequency is right?
Did you measure what voltages that you can around the horizontal sweep circuit?
If you have a compact fluorescent bulb?
If you hold one near the horizontal output tube or flyback it should glow.

[Aperna1985]

I might have a CFL bulb I have to look.

The 6GB6G rectifier tube tests good on my tube tester and shows no leakage. It's not super strong just in the middle and does have a little bit of a blue glow. The TV is off in the picture.

I don't know how to check frequency, is there a way without a scope?

I have those tube adapters that have tabs to check voltage so I will try to run through the horizontal circuit this weekend.

[init4fun]

Originally Posted by Aperna1985

I might have a CFL bulb I have to look.

The 6GB6G rectifier tube tests good on my tube tester and shows no leakage. It's not super strong just in the middle and does have a little bit of a blue glow. The TV is off in the picture.

I don't know how to check frequency, is there a way without a scope?

I have those tube adapters that have tabs to check voltage so I will try to run through the horizontal circuit this weekend.

Hi Aperna1985,

Not scolding or playing Tube Nazi* here, but the 6GB6G is not a rectifier, it's the Horizontal Output

* Think Seinfeld's "Soup Nazi", , , but for tubes......

[Aperna1985]

Originally Posted by init4fun

Hi Aperna1985,

Not scolding or playing Tube Nazi* here, but the 6GB6G is not a rectifier, it's the Horizontal Output

* Think Seinfeld's "Soup Nazi", , , but for tubes......

You're 100% right thank you. It's a 1B3GT which test strong actually. I could always buy another one in case.

[Notimetolooz]

Originally Posted by Aperna1985

I don't know how to check frequency, is there a way without a scope?

Without something on the TV screen it is hard to estimate the horizontal frequency. A scope would also show the wave shape which is useful.
You don't need a scope for AM radios but working with TVs they are handy.

I don't suppose you have a frequency counter. I've never used a counter for that purpose but there may be a way to use it.

The fact that you got flashes of light on the screen when you changed a switch suggests the HV doorknob cap is OK. Also didn't you say you got a zap when you got to close to the side of the CRT? That would also suggest the cap is OK and there isn't too much leakage at any place else.