Pilot TV-37 Restoration

[Crist Rigott]

Fixed it. Ready for this. I adjusted the H. Hold and the severe bending at the top of the picture was gone.

However, the picture was still very dim. You see, I recapped my second TV-37 and that one had a lot brighter picture. Then I remembered that L17 has a 1N34 video diode that I never replaced. I pulled L17 and changed out the diode with a 1N34A, 2 resistors, and a 250pf mica cap. Reinstalled L17 and the picture was a lot brighter. I put my crosshatch generator on it and adjusted the vertical size, horizontal size and linearity, and picture centering. All is well.

Thanks to all for your suggestions.

Here are some pictures of the before and after L17.

[Kevin Kuehn]

That's very interesting. Those old germanium diodes seem to develop internal resistance over time and apparently yours was leaking some DC offset onto the video amp grid, messing with sync and brightness. Anyhow good fix.

[Dave A]

Do I see a third resistor changed? To the left of the mica on pix 4 and 8 from the top.

[Jeffhs]

Originally Posted by Popester

Interesting way that you tune the channels. Much like a radio. Obviously there was no detent for the channels. Would this be a split sound design for the sound and video IF?

DuMont made a console TV in the early 1950s with the same type of tuner this set has. These tuners would receive all 13 VHF TV channels at the time (including now obsolete channel 1), and also the FM broadcast band between channels 6 and 7.

[Crist Rigott]

Originally Posted by Dave A

Do I see a third resistor changed? To the left of the mica on pix 4 and 8 from the top.

Just saw this. Yes on the third resistor.

[JohnCT]

Originally Posted by Jeffhs

DuMont made a console TV in the early 1950s with the same type of tuner this set has. These tuners would receive all 13 VHF TV channels at the time (including now obsolete channel 1), and also the FM broadcast band between channels 6 and 7.

Maybe a Mallory Inductuner? My Andrea has one and it works perfectly with zero attention paid to it.

John

[bandersen]

Yes, Dumont, Stromberg Carlson, Andrea and others used a Mallory Inductuner in the late 40s. They phased them out in the early 1950s.

This set uses less complex and expensive variable capacitor.

[Electronic M]

Some SC sets and Crosleys were actually Dumonts in cabinets made to the spec of the badge being slapped on.