I’m Back! Pilot TV37 - Videokarma.org TV - Video

Chris K · #1 11-09-2022, 10:22 PM

Hi guys… asking you stand by once again for another all hands on deck. Got the infamous 3” Pilot TV37 on the bench. Of course the first question…anybody got a line on a fresh 3KP4? I think I’ll find some hen’s teeth before I come across one of them!

Electronic M · #2 11-10-2022, 09:31 AM

I did one earlier this year. I need to get a set of the ships wheel knobs, and add the CRT heater protection diode (been variacing it as a protection).

If yours is like mine you'll need to change about %90 of the resistors along with the caps to get good stable operation.

Tube TV · #3 11-10-2022, 01:16 PM

Lucky you. I still want to get a Pilot.

Chris K · #4 11-10-2022, 06:52 PM

I'm a joyful recapper but 5000pf 6000V caps in the HV circuit? Jeeze...it only makes 2.5K in the HV circuit for the CRT! IDK if I can even find something like that. These are waxies. Can I sub ceramic caps?

Electronic M · #5 11-10-2022, 08:08 PM

Quote:

Originally Posted by Chris K

I'm a joyful recapper but 5000pf 6000V caps in the HV circuit? Jeeze...it only makes 2.5K in the HV circuit for the CRT! IDK if I can even find something like that. These are waxies. Can I sub ceramic caps?

You can only use ceramics if you double the capacitance, otherwise you'll have incurable non-linearity in the sweep.

I just go on mouser and get Wima brand red rectangular film caps of that voltage and .0047uF/4700pF they work great in all the various brands of electrostatic sets I've tried them in including my TV-37, and they're the cheapest new cap I know of... Only downside is this leads are short so I have to solder extensions on... Besides that I can't complain. I keep a certain number of them in stock so I can buy and start on an electrostatic deflection set any day I feel like it.

Chris K · #6 11-10-2022, 08:14 PM

Quote:

Originally Posted by Electronic M

You can only use ceramics if you double the capacitance, otherwise you'll have incurable non-linearity in the sweep.

I just go on mouser and get Wima brand red rectangular film caps of that voltage and .0047uF/4700pF they work great in various brands of electrostatic sets. I keep a certain number of them in stock so I can buy and start on an electrostatic deflection set any day I feel like it.

Thanks Tom...I went through DK and didn't find anything appropriate but I did search Mouser and got the exact cap you described...in fact 3 of them. Before I replaced anything, I brought this up very slowly on a Variac and a succession of bulbs. I have static out of the speaker, all the tubes are lit and the CRT filament is lit. No light on the screen though. How do you check the HV on one of these 3KP4 tubes?

Chris K · #7 11-10-2022, 08:22 PM

Also, I picked up a 1948 Motorola VT71 today. It's in beautiful condition...outside. IDK anything about the CRT or the functionality but I had to grab it. Busy winter coming!

Chris K · #8 11-10-2022, 08:26 PM

Quote:

Originally Posted by Chris K

Also, I picked up a 1948 Motorola VT71 today. It's in beautiful condition...outside. IDK anything about the CRT or the functionality but I had to grab it. Busy winter coming!

This is a picture of one on eBay...same model as I purchased.

Electronic M · #9 11-10-2022, 08:45 PM

Quote:

Originally Posted by Chris K

Thanks Tom...I went through DK and didn't find anything appropriate but I did search Mouser and got the exact cap you described...in fact 3 of them. Before I replaced anything, I brought this up very slowly on a Variac and a succession of bulbs. I have static out of the speaker, all the tubes are lit and the CRT filament is lit. No light on the screen though. How do you check the HV on one of these 3KP4 tubes?

I think I just used my 30KV HV probe and looked for a little on the bottom end.y fluke only does 1KV, and my older meters only do 1600V...

Chris K · #10 11-10-2022, 10:53 PM

Quote:

Originally Posted by Electronic M

I think I just used my 30KV HV probe and looked for a little on the bottom end.y fluke only does 1KV, and my older meters only do 1600V...

Any of the crt base pins, except for the filament, will show HV? According to the schematic the HV is 2.5K. There’s no traditional donut shaped flyback on the tv. It’s like a large adjustment coil winding

Electronic M · #11 11-11-2022, 08:50 AM

The grid and cathode shouldn't have HV. The deflection plates should. I think I measured HV off the point where the focus divider string under chassis ties in to HV box output.

Chris K · #12 11-11-2022, 09:01 AM

Got it. Thanks so much

Chris K · #13 11-17-2022, 07:16 PM

Quote:

Originally Posted by chris k

got it. Thanks so much

first light!!!!

Electronic M · #14 11-17-2022, 09:02 PM

Quote:

Originally Posted by Chris K

first light!!!!

Good progress.

Chris K · #15 11-18-2022, 08:58 AM

Thanks Tom...replaced the HV caps and the electrolytics. Surprised as hell and that picture shows the tube at reduced current...I had a 150 watt bulb in the dim bulb setup. I wanted to go to straight 117 volts and start fiddling with controls but I walked away. I was tired and excited at the same time at 8pm after a long day. That's a bad place to start fiddling with a 75 year old piece of vintage electronics that just woke up after 50 years!