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

[vortalexfan]

Originally Posted by Electronic M

You want to use ammonia to clean the mating surfaces. The factory glue responds best to ammonia and if you don't clean the factory glue off it will continue to degrade and undermine anything glued to it.

OK, my parents have some ammonia in their basement, I might have to borrow some.

But no one answered my question about the electrolytic caps in the big Zenith TV, I had asked if it was ok to just replace the bad sections of the multi-section caps and continue to use the good sections of the multisection caps, or if I should just replace all of the electrolytics and be done with it?

[DavGoodlin]

Originally Posted by vortalexfan

But no one answered my question about the electrolytic caps in the big Zenith TV, I had asked if it was ok to just replace the bad sections of the multi-section caps and continue to use the good sections of the multisection caps, or if I should just replace all of the electrolytics and be done with it?

If you find the caps are full-on open with very high ESR, I'm not sure they would reform. It the old days, I usually just bridged a new one across it to see if issue would go away. More importantly, if the cannot charge up to rated voltage using a high-impedance cap tester with an eye tube, just disconnect those sections and replace one cap as needed.

Often just the half-circle (usually the highest value) cap section is suspect as it gets the full DC supply initially before the tubes warm up and begin to draw current.

I usually find one out of four open, showing very high ESR, almost always on the lower values like 2, 5, 10, 20mf etc. Even if ESR is low, you may still find that cap becomes leaky at rated voltage. It probably went bad long ago but a good set like this Zenith might not show symptoms.

[vortalexfan]

Originally Posted by DavGoodlin

If you find the caps are full-on open with very high ESR, I'm not sure they would reform. It the old days, I usually just bridged a new one across it to see if issue would go away. More importantly, if the cannot charge up to rated voltage using a high-impedance cap tester with an eye tube, just disconnect those sections and replace one cap as needed.

Often just the half-circle (usually the highest value) cap section is suspect as it gets the full DC supply initially before the tubes warm up and begin to draw current.

I usually find one out of four open, showing very high ESR, almost always on the lower values like 2, 5, 10, 20mf etc. Even if ESR is low, you may still find that cap becomes leaky at rated voltage. It probably went bad long ago but a good set like this Zenith might not show symptoms.

Well the Main Power Supply Filter Cap (which in these Zenith's, at least the ones I have) is just a single section can seemed to measure what I'm assuming to be either open or shorted as on my ESR tester (one of the small digital readout ones that you would get as a kit online either fully assembled or you would have to assemble yourself) was showing 29pF on the readout with no ESR reading or anything.

The sections that tested good had ESR readings of .77 ohms or less, (those were on the two 4 section cans) and the one 4 section can that had one bad section the bad section showed a lone 29pF readout on the display and no ESR readout, the one that had 2 sections bad also read 29pF and no ESR reading on the display, which like I said I'm assuming that means the sections are open or shorted.

The paper caps in the TV all read pretty close to spot on MFD value wise, but that doesn't mean anything, they could still be leakier than all get out.

[Electronic M]

Originally Posted by vortalexfan

OK, my parents have some ammonia in their basement, I might have to borrow some.

But no one answered my question about the electrolytic caps in the big Zenith TV, I had asked if it was ok to just replace the bad sections of the multi-section caps and continue to use the good sections of the multisection caps, or if I should just replace all of the electrolytics and be done with it?

I did that on my 29JC20 and it shorted or opened a section every 2 weeks after that until the 3rd time I gave up and changed them all.

[Notimetolooz]

It is best to just go ahead and change them all rather than go through the trouble of having to remove the chassis again. Caps are really not that expensive compared to other things that sometimes have to be replaced.

In your question about the flyback cover that is falling apart, you will have to do something to support the centering magnet rings at the very least.
There is a thread somewhere here that show how someone built up a replacement cover for another type of set.
I have also seen a post about someone else that made a new cover using a 3D printer for another set.

[vortalexfan]

Originally Posted by Notimetolooz

It is best to just go ahead and change them all rather than go through the trouble of having to remove the chassis again. Caps are really not that expensive compared to other things that sometimes have to be replaced.

In your question about the flyback cover that is falling apart, you will have to do something to support the centering magnet rings at the very least.
There is a thread somewhere here that show how someone built up a replacement cover for another type of set.
I have also seen a post about someone else that made a new cover using a 3D printer for another set.

You mean the yoke cover? Because that's what fell apart on the 23" Zenith of mine, I unfortunately don't have access to a 3D printer, let alone the design plans for this TVs Yoke cover.

[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.