1950s or '60s vintage Zenith TVs, Need some info

[Kevin Kuehn]

Primarily a vertical linearity issue. Could be linearity and/or height control or a cap. I don't have any service info so I'm not of much help.

[damen]

If your tuner has this switch on the back, it's purpose is to switch on the UHF B+ and dial light. The 3 back connections are for the lights. The left terminal is the common one, usually has a brown wire connected to it, and the VHF light connects to the right terminal, UHF light connects to the middle terminal. On channels 2-13 the two outside terminals have continuity, when the UHF position is selected, the right terminal disconnects from the left and the center terminal is now connected to the left one. Your switch needs cleaning. It can be opened up and fixed, just be careful parts don't spring out!

[old_coot88]

I wouldn't open the switch up. Just give it a shot of Deoxit or similar. Then let it work a few cycles.

[vortalexfan]

Originally Posted by Kevin Kuehn

Primarily a vertical linearity issue. Could be linearity and/or height control or a cap. I don't have any service info so I'm not of much help.

well that's what I was thinking as well, and I was trying to adjust the height adjustment (called Vertical Size on this TV) but that control is inset within the Peak Picture control and I can't seem to adjust it because none of my screwdrivers I have are long enough to go inside that Peak Picture contol knob to adjust the Vertical Size Adjustment.

[vortalexfan]

Originally Posted by old_coot88

I wouldn't open the switch up. Just give it a shot of Deoxit or similar. Then let it work a few cycles.

I'll give it a shot.

[vortalexfan]

I'm just curious, but can missing centering rings cause the issues my TV is having with the weird linearity issues?

[ronl]

Hi Vortalexfan.in the past,if I needed a long skinny adjustment slot screwdriver,I would take a piece of coathanger and hammer one end flat.then take a file and clean up the end.then bend a 90 deg at the other end for a handle..has worked well for me. RonL

[vortalexfan]

I actually did end up finding a screwdriver that worked.

[vortalexfan]

OK, so I had a really weird issue just come up on my 23" Zenith TV, C61 which is apparently a bypass cap of some sort for the Horizontal Output Tube just went up in flames literally, which I was able to extinguish the flame by blowing it out like a candle (it was burning like a candle would.)

any ideas as to what would cause that to happen?

Do you think that this issue might have something to do with the weird linearity issues that I was having?

I posted a screenshot of the schematic showing the part of the circuit where the strange failure took place.

[old_coot88]

Looks like the cap just randomly decided to short. No doubt the resistor supplying B+ cooked also.

[vortalexfan]

Originally Posted by old_coot88

Looks like the cap just randomly decided to short. No doubt the resistor supplying B+ cooked also.

OK, well it was a modern replacement cap (the yellow film variety) and it was one i had salvaged out of a radio I had recapped a couple of years ago that I ended up having to scrap out because I wasn't able find some parts to fix the rest of the radio.

That B+ Supply Resistor was an 8.2kOhm 3W resistor so not a very common value...

[vortalexfan]

OK so here's a picture of the burned up capacitor, has anyone seen a capacitor fail like this before, especially one that's only a couple years old?

[Electronic M]

Originally Posted by vortalexfan

OK so here's a picture of the burned up capacitor, has anyone seen a capacitor fail like this before, especially one that's only a couple years old?

You probably ruined it when you salvaged it...the plastic sides and dielectric/foil roll melt easily. If you accidentally touched your iron to the side of the cap and melted it a bit you could have shorted together the 2 capacitor metalized plastic plates, or damaged the dielectric enough to make failure easier.

I've ruined a few yellow caps with my iron myself....I don't like that they can melt easily so I only use them if I'm restuff paper caps or dealing with a situation where I need extra long leads and I don't want to Western Union splice longer leads on.

[Yamamaya42]

Also, that thing is always being hammered by high freq AC by the horz circuits,I always go for something at least 100v higher than the original rating.

[vortalexfan]

Originally Posted by Yamamaya42

Also, that thing is always being hammered by high freq AC by the horz circuits,I always go for something at least 100v higher than the original rating.

The original cap was a .047 uF 200V and the replacement I installed was a .047 uF 630V capacitor...