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

[Notimetolooz]

Ah! Yes I meant the yoke cover. I've got to make sure I get my morning coffee before I reply next time.
I'll see if I can find the thread where someone build a cover from scratch. I think his was a RCA. It wasn't simple, he used plastic pipe, thin plywood, etc.
EDIT: OK, it was a Philco Seventeener. The yoke stuff starts at post # 93. You probably will have to use different materials. I see someone did something similar that was all plastic.
http://videokarma.org/showthread.php...Rigotti&page=7

[vortalexfan]

OK, so I'm trying to come up with a list of replacement capacitors to order for my Zeniths and the 23" Zenith is giving me problems because there's three Bumblebee Caps in there and when I tried entering the color code from those caps into a capacitor color code decoder app online it came up with 2.2 MFD on one of the capacitors and the other two came out as 4.7 MFD capacitors all of them of which were 10% tolerance and 400 WVDC.

But that doesn't seem quite right when compared to other capacitors nearby which are all under 1 MFD (.15 MFD or less.)

I looked at the parts list in the Sam's and they do list a couple of capacitors at 4.7 and one at 2.2 but they don't have any voltages listed for them and they don't show if they're paper caps or if they're Mylars, or Ceramic Disc Caps in the description and the 4.7 and 2.2 values given for those capacitors don't say whether its MFD or MMF.

Any Help would be appreciated.

[Tom9589]

Find out where these capacitors are in the schematic. Sams should have the exact value next to the capacitor's symbol. Read Sams footnotes to determine if these capacitors are MF or MMF. Usually, if the value is less than 1, it's in MF. If it is more than 1, it's in MMF.

[vortalexfan]

Originally Posted by Tom9589

Find out where these capacitors are in the schematic. Sams should have the exact value next to the capacitor's symbol. Read Sams footnotes to determine if these capacitors are MF or MMF. Usually, if the value is less than 1, it's in MF. If it is more than 1, it's in MMF.

The odd part is that the Sam's that I have (I bought a PDF download from Sam's) doesn't have the schematic for the main TV Chassis, just the tuner and the remote chassis, nothing for the main TV Chassis though... at least not that I could see.

[old_coot88]

Originally Posted by Tom9589

...Read Sams footnotes to determine if these capacitors are MF or MMF. Usually, if the value is less than 1, it's in MF. If it is more than 1, it's in MMF.

Should oughta read: "if less than .001 mf it's in mmf (micro-microfarad, aka picofarad or pf)

Microfarad or mf (sometimes written mfd) = one millionth of a farad
Micro-microfarad or mmf (sometimes written mmfd or pf) = one millionth of a mf.

Typically values below .001 mf are in mmf/mmfd/pf.

[Tom9589]

And let us not forget the new nomenclature that seems to be in use everywhere today: the nanofarad or nF which is one thousandth of a microfarad.

[vortalexfan]

OK so I figured out what those Bumblebees were, they were .022 μF 400 VDC
and 2 .047 μF 400 VDC capacitors so I ordered some 630 VDC replacements of those capacitors, since they were using the same capacitance values as the modern caps use.

[vortalexfan]

I've already got the two .047 MFD Bumblebee caps replaced in the TV (I actually had a couple of replacement caps laying around of that value that I forgot I had laying around) so now I just need to wait for the rest of my capacitors that I ordered to arrive, which I'll have to work on this more when I get back from my trip.

[vortalexfan]

OK, so I got some more of the paper caps replaced and I went to power on the TV to check to see if I was getting anything on the Screen, and for some reason the set isn't getting any power, the tubes aren't glowing, no static out of the speaker or anything, and I didn't touch anything related to the power supply all I did was replace some of the capacitors (which I took the old ones out and installed them like they went in originally when there was room for the soldering iron to fit without damaging surrounding components.)

Any ideas as to what could be causing this issue? I know it powered on fine before I started replacing components, there is a circuit breaker on the front of the TV, and I know those are notorious for going bad, could that be part of my problem?

[Electronic M]

Circuit breakers can sometimes beco sensitive to mechanical vibration. I'd ohm it out and if necessary wiggle it and or push/pull the button a couple of times before condemning it.

Sometimes power switches will get sticky and or dirty and the contacts will stay open or closed despite the handle being in the opposite state.

Another possibility is if you accidentally shorted the heater wiring there's often a fusible link (piece of magnet wire thinner than the rest of the wiring designed to burn open like a fuse if there's a short).

There's enough that could go wrong that no definite conclusion can be made from available info.
What I typically do in cases like this is pull the chassis and do bench resistance and voltage tests.

[vortalexfan]

Originally Posted by Electronic M

Circuit breakers can sometimes beco sensitive to mechanical vibration. I'd ohm it out and if necessary wiggle it and or push/pull the button a couple of times before condemning it.

Sometimes power switches will get sticky and or dirty and the contacts will stay open or closed despite the handle being in the opposite state.

Another possibility is if you accidentally shorted the heater wiring there's often a fusible link (piece of magnet wire thinner than the rest of the wiring designed to burn open like a fuse if there's a short).

There's enough that could go wrong that no definite conclusion can be made from available info.
What I typically do in cases like this is pull the chassis and do bench resistance and voltage tests.

I monkeyed with the circuit breaker and sure enough it came back to life. But I'm still not getting a picture or raster on the screen, and still no HV.

[Electronic M]

Originally Posted by vortalexfan

I monkeyed with the circuit breaker and sure enough it came back to life. But I'm still not getting a picture or raster on the screen, and still no HV.

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).

[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).

I'm not sure if it's the vertical or horizontal oscillator that's running but one of them is running for sure because I hear a high pitched whining noise coming through the speaker.

[vortalexfan]

The Flyback Transformer looks like its in good shape yet, it only has one wax drip underneath it inside the HV Cage and that's it.

As far as measuring the Voltages on the Horizontal Output Tube, I thought you weren't supposed to test that, because of a chance of frying your multimeter?

[Electronic M]

Originally Posted by vortalexfan

I'm not sure if it's the vertical or horizontal oscillator that's running but one of them is running for sure because I hear a high pitched whining noise coming through the speaker.

Its possible the horizontal oscillator is running, but there are a litany of other things that could cause squealing through the speaker. Including self-oscillation in the IF system. You should take measurements to check.

Originally Posted by vortalexfan

The Flyback Transformer looks like its in good shape yet, it only has one wax drip underneath it inside the HV Cage and that's it.

As far as measuring the Voltages on the Horizontal Output Tube, I thought you weren't supposed to test that, because of a chance of frying your multimeter?

There's only one terminal on that tube that can harm a meter: the plate. The plate is always the top connector on the tube. Measure the other terminals (the ones on the bottom) and your meter will be fine and you'll know more about why there's no HV.

While it is nice your flyback looks good, looks are not conclusive. I've seen scary ones work fine and really nice ones that are shot.

Also if you are running it for more than 30 seconds after warmup and there's no horizontal osc you can potentially damage both the flyback and H output tube.