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

[vortalexfan]

Originally Posted by Electronic M

Measure the voltage on the grid and screen grid of the horizontal output tube.
The grid will tell you if you're horizontal oscillator lives and the screen can give info on whether there's issues on the flyback side.

The entire horizontal system has to work for there to be HV. It's typically much faster to troubleshoot that system than it is to shotgun parts (though replacement of paper and lytic caps is probably wise).

OK, so the Control-Grid (Pin 3) was 125 VDC and the Screen-Grid (Pin 2) was -0.5 VDC when I measured them, and the Horizontal Output Tube is a 6GE5 12-Pin Compactron Tube, so I'm not sure what that means in regards to the condition of the Horizontal/High Voltage Circuitry goes.

[Electronic M]

Measure voltage on pins 2 and 3.

Do NOT measure pin 7.

Generally a penthouse tube's elements go: heater, cathode, control grid, screen grid, suppressor grid, plate (pin mapping is often random). And if grid is used without screen or suppressor in the sentence then control grid is meant. If you looked at the tubes pinout/datasheet you shouldn't need an explanation of which pin is which. The first datasheet hit on Google has a plenty good explanation.

[vortalexfan]

Originally Posted by Electronic M

Measure voltage on pins 2 and 3.

Do NOT measure pin 7.

Generally a penthouse tube's elements go: heater, cathode, control grid, screen grid, suppressor grid, plate (pin mapping is often random). And if grid is used without screen or suppressor in the sentence then control grid is meant. If you looked at the tubes pinout/datasheet you shouldn't need an explanation of which pin is which. The first datasheet hit on Google has a plenty good explanation.

See my updated comment in post 107.

[Electronic M]

Control grid should be negative (usually in the -50V to -75V range). Refer to the schematic for correct value. If control grid isn't sufficiently negative the osc is dead or it's signal isn't getting to the output tube.

Screen grid should be positive in the 75 to 200V range. Again refer to schematic.

Part of me wonders if you have the two mixed up.... regardless it looks like you're missing horizontal oscillator signal and or the osc isn't working.

If the screen grid is truly negative like that it means that the damper, flyback fuse or flyback is open. The screen grid voltage drops below spec when the plate isn't drawing current and the screen acts as a stand in plate...If it has dropped that low then the screen current is dangerously high and the tube may already be damaged. It could possibly get that low if there's no osc signal at the grid and the plate is not drawing current from an open circuit.

[vortalexfan]

Originally Posted by Electronic M

Control grid should be negative (usually in the -50V to -75V range). Refer to the schematic for correct value. If control grid isn't sufficiently negative the osc is dead or it's signal isn't getting to the output tube.

Screen grid should be positive in the 75 to 200V range. Again refer to schematic.

Part of me wonders if you have the two mixed up.... regardless it looks like you're missing horizontal oscillator signal and or the osc isn't working.

If the screen grid is truly negative like that it means that the damper, flyback fuse or flyback is open. The screen grid voltage drops below spec when the plate isn't drawing current and the screen acts as a stand in plate...If it has dropped that low then the screen current is dangerously high and the tube may already be damaged. It could possibly get that low if there's no osc signal at the grid and the plate is not drawing current from an open circuit.

Well I've just about got this TV recapped I've replaced all of the paper caps except for 2 of them, and then I've replaced all of the electrolytics except for 2 of them, and its because they were values I didn't have on hand, but I have them on order right now.

One thing I noticed is that one of the electrolytic caps was in the Boost circuitry and that was one of the caps that measured bad when I measured it with my ESR meter, and also the main filter cap (which consists of 3 80 mfd 450V caps in series) also all measured bad which are part of the B+ voltage circuitry which might of explained the low voltages on the Horizontal Output Tube.

Also I noticed there's a neon bulb under the TV Chassis near the Horizontal circuitry, what is the purpose of that neon bulb?

[Electronic M]

Without the schematic Infront of me I can't tell you for sure what the neon does. Zenith did use them as spark gaps on some monochrome sets. It could also be a voltage reference or a couple of other things.

[vortalexfan]

I got a screenshot of the schematic for my Zenith 23" TV showing where the Neon glowbulb is in the circuit, and from what I can see, it seems to be in the Vertical Deflection Circuit, but what purpose it's serving there I'm not sure, but I do know its not serving the purpose of spark-gap service because there's a couple of wires on the picture tube socket serving that purpose, as can be seen on the schematic.

See the schematic excerpt below.

[vortalexfan]

Well I finished recapping the TV and went to power it on and I heard the sound of what sounded like the high voltage coming up but instead of it being only for a few seconds it was for the whole duration of the warmup time and there was no audio, and then I saw smoke.

That's when realized that I installed the wrong value of capacitor in place of C3B which is the filter capacitor for the output transformer, which was supposed to be a 10 MFD 450VDC capacitor, and instead I put a 100 MFD 63 VDC capacitor in its place, which that capacitor is supposed to be filtering the 270V line going into the output transformer.
So because I put the wrong capacitor in, the 100MFD 63VDC capacitor couldn't handle the 270V going into the capacitor which was basically overloading the capacitor and causing it to vent (thankfully I shut it off before it vented.)

And Unfortunately I don't have a 10MFD 450VDC capacitor in my stash like I thought I did (well I do but its an old Sprague "Atoms" capacitor that is really large and it wouldn't fit very easily in the already tight space under the TV chassis), so I'm going to have to order one.

[Tom9589]

You didn't show enough of the circuit to be able to determine what signal is driving the neon bulb. I suspect it's some sort of horizontal blanking signal, not a vertical signal.

[vortalexfan]

Here's a better shot of the schematic showing the Neon Bulb and the circuit its in. It looks to be part of the Horizontal circuit as you said, but I'm not sure what its purpose is in the circuit.

See picture below.

[vortalexfan]

OK a little update, I did end up using the Sprague capacitor I had, and I did actually have room underneath for it after all, but just barely.

Do you know how I would go about bypassing the circuit breaker on this TV?

I'm asking because everytime I move the TV it trips and to get it to reset I have to go under the chassis and reset it with a screwdriver (with the unit unplugged of course) because the pushing the red button on the circuit breaker doesn't do anything anymore (I've tried jiggling it rotating it, pushing it, pulling it, etc. and it doesn't reset the breaker).

[init4fun]

Originally Posted by vortalexfan

Do you know how I would go about bypassing the circuit breaker on this TV?

Well, , , that's an easy question, if you suspect the breaker has gone defective, you replace it with a brand new one of the exact same rating

Any other talk of "bypassing" bypasses all kinds of safety and common sense, so I have no input on that..........

[vortalexfan]

Originally Posted by init4fun

Well, , , that's an easy question, if you suspect the breaker has gone defective, you replace it with a brand new one of the exact same rating

Any other talk of "bypassing" bypasses all kinds of safety and common sense, so I have no input on that..........

When I was referring to bypassing the circuit breaker I just meant temporarily for testing purposes to check my work as far as my capacitor replacement went.

[Electronic M]

One "safe" way to bypass a circuit breaker for testing is to get a fuse the same amperage and tack that in parallel with the open breaker....Of course if there's a fault causing the tripping you'll waste fuses trying to troubleshoot it.

[vortalexfan]

Originally Posted by Electronic M

One "safe" way to bypass a circuit breaker for testing is to get a fuse the same amperage and tack that in parallel with the open breaker....Of course if there's a fault causing the tripping you'll waste fuses trying to troubleshoot it.

Well I'm pretty sure its not a fault in the circuitry because the breaker will "trip" without me even having the TV plugged in and powered on, all I'm doing is moving the TV from laying on the TV screen (face down) to moving it into the upright position (the TV screen facing the wall and the bottom of the chassis facing the floor) and after I do that I plug the TV in and go to power it on and the TV is dead and I unplug the TV and flip it back onto its face and check the breaker and sure enough its "tripped" (it doesn't beep with the continuity test on my DMM) and the only way to "reset" the breaker is to use a screwdriver because the red reset button doesn't doesn't do anything to reset the breaker element for some reason.

Also when I looked at the breaker it doesn't look like its original because there's a blob of solder on the chassis of the TV under the circuit breaker and a little blob of solder on the bottom of the circuit breaker itself but the solder blobs don't match up (almost like the circuit breaker was taken from another TV and installed inside this one to replace the original circuit breaker.)