Pilot tv brightness problem

[old_coot88]

Well, I'm gonna hafta bail on this one and leave it to the experts. With 106V positive on the grid relative to cathode, and still be showing an in-focus (albeit dim) raster is beyond credulity. Maybe a quirk of electrostatic jugs? I may learn sumpthln new here.

[old_tv_nut]

Originally Posted by old_coot88

Well, I'm gonna hafta bail on this one and leave it to the experts. With 106V positive on the grid relative to cathode, and still be showing an in-focus (albeit dim) raster is beyond credulity. Maybe a quirk of electrostatic jugs? I may learn sumpthln new here.

You missed the minus sign

Pin 2, G1 is -120, pin 3, K is -50 to +67

So G1 to K is -70 to -187, Sams says -172, so that's within range of the SAMS.

[old_coot88]

Originally Posted by old_tv_nut

You missed the minus sign

Thanks. Geriatric brain fart.

[jr_tech]

Originally Posted by old_tv_nut

You missed the minus sign

Pin 2, G1 is -120, pin 3, K is -50 to +67

So G1 to K is -70 to -187, Sams says -172, so that's within range of the SAMS.

These voltages don’t seem correct... according to the 3kp4 data sheet, typical grid cut off is at most -90 volts not -172

https://frank.pocnet.net/sheets/168/3/3KP1.pdf

jr

[old_tv_nut]

Originally Posted by jr_tech

These voltages don’t seem correct... according to the 3kp4 data sheet, typical grid cut off is at most -90 volts not -172

https://frank.pocnet.net/sheets/168/3/3KP1.pdf

jr

Thanks, 172 seemed high, but I had no knowledge of the tube spec, so kept my mouth shut.
Still need to hear the results of resistance readings and voltage readings with a good signal to try to figure this out.