Pilot tv brightness problem
 

What would cause the loss of brightness in the pilot tv the hv is up ok but the brightness is 90% gone and the crt is fine.

Hi Timmy,

Main question:
Do you have both schematics (Sams and Riders)?
I should not start any work without them!

Re-cap-job done?

There is some safety work to safe the life of the CRT to do, too.

I have collected many reports about this little Pilot TV.

I like to send you this literature by email if wanted.:yes:
To anybody else who likes that stuff (print-friendly), too.......

It will give you a perfect overview about issues and how to fix them!

Regards,
TV-collector:stupid:

Hi Timmy,

If you dig into the material I just sent to you, you will be traced to that video-diode 1N34!
This will be your first job to check.:yes:

We have to realize, that because of aging these old diodes becoming more and more the status of troublemakers, like the old ugly caps and resistors, which are often out of tolerance.:thumbsdn:

Good luck and happy weekend,
TV-collector:stupid:

Picture is ok hv is good all tubes check ok b+ is also good. If the 1n34 was bad I would think the picture quality would suffer not the brightness. The brightness problem came out of nowhere. There is no mention in the rider’s about the 1n34 and the loss of brightness only the loss of picture and probably sound.

Sure would luv to see the circuitry by which brightness would be affected by the diode.

:saywhat::headscrat

What is the heater voltage on the CRT?

jr

low!
If i recall, he is using some odd rare tube with a very low heater v.

Yes I’m using a d100 crt but it’s not that I unplugged that crt and plugged the 3kp1 in and same thing heater voltage is good.

Which CRT was in the set when you first noticed the brightness drop?

jr

D5-100 crt

It’s odd pin 1 of v9 if I use the meter on resistance from ground to pin 1 I get full brightness and when I take it off the brightness slowly fades back to dim almost like depleting a cap. No bad resistors that I found yet.

So what is V9? Is it the CRT or something else? Any chance of posting a (hopefully legible) print of the video and CRT region?

V9 is dc restore and sync tube

Sams here:

http://www.earlytelevision.org/pdf/p...sams_62-16.pdf

jr

Yes that’s the one and I also checked the 1n34 for laughs and it’s good. And also checked all the power supply electrolytics all good. I’m lost at this point. The resistors at the bright pot are spot on.