Ok, well where would I source a new circuit breaker for this TV?

Dude, your not trying hard enough here, and I'm not usually one to do someone's homework, but since ya asked nicely, just this once I'll give ya a hand ;

This is one listing out of a few I found while searching "Replacement Circuit Breaker for vintage TV" ......



https://www.ebay.com/itm/352518574185

Ok, take at easy dude, I was asking because I thought you were suggesting that I was going to find them brand new somewhere which I wasn't sure how that was going to be possible seeing as TVs haven't had circuit breakers in them like that since the 1980s, I didn't realize you meant going to ebay and finding a NOS circuit breaker.

This is the first TV I've worked on that had a circuit breaker on it so I didn't know... 😶

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.)

OK, I found a proper replacement circuit breaker for my TV. It was $5.50 plus $4.50 shipping.

Its a GC Electronics NOS Exact Replacement 2.75 Amp Circuit Breaker, which is what the breaker that came out of it was rated at (it was a Zenith replacement part because the part number on the breaker in this unit was the same as the one listed in the Sam's Service Info), like I said I don't think the breaker in this TV is the original breaker because like I said it shows evidence of being replaced at one point in time because the solder blob at the bottom of the circuit breaker that would hold it to the chassis (or possibly ground the breaker to the chassis) was disturbed and wasn't re-flowed.

OK, so a little update, I did manage to repair the circuit breaker, and I did get the TV to produce a full screen raster, but I'm not getting anything out of the tuner (no snow or white noise just a blank raster), and I think it might be because the tuner has some dead tubes in it, because when I looked at the tuner I only saw one of the tube glowing in the VHF tuner and the UHF tuner tube isn't glowing either.

See picture below to see what the TV looks like currently.

Well I'm happy to hear you've got it working, without any of that nasty "bypass" business :thmbsp:

That neon bulb is connected between the horizontal section and the CRT.
I think it passes pulses from the horizontal output transformer to the grid to blank the CRT during the horizontal re-trace. You might not even notice if it was not working, many earlier sets did not bother with horizontal blanking because the beam travels so fast it doesn't light the phosphor much.

In early sets with full DC response, the retrace would normally be at or below black (with the correct brightness control setting). When sets were designed with less or no DC coupling/restoration, V and H blanking was needed to prevent retrace visibility on dark scenes. Later, with color broadcasts, the color burst could become visible in the retrace if there was no H retrace blanking.

Go with your gut, and check the tubes in the tuner first.

Run the set a few mn & see if the tubes get hot. Its pretty
rare on a parallel filament set to get an open tube never mind
two of them.

Next run set. Change channels. You should see & hear a lot of noise
from the switches making & braking.
If you dont its father down the line, prob one of the IF tubes.

73 Zeno:smoke:
LFOD !

Well I put the set back together ran it for a little bit and all I'm getting through the speaker is a very pronounced "vertical Oscillator" noise through the speaker and some very faint white noise coming through the speaker, I have a converter box hooked up to the set and and I was going through all of the channels and I wasn't getting any signal through whatsoever, not even the backlight bulbs for the tuner are working but yet the motorized tuning is working (you push the button on the front panel of the TV and the tuner advances through the channels as it should) but since the pilot lights aren't working I can't see what channel I'm on.

Also as far as the picture goes, I can't tell if the vertical and horizontal hold are adjusted correctly because I can't see the lines from them on the screen because its just a bright grey color and you can't see any snow or anything on the screen..

This era of Zenith used a barrel connector for tuner B+ and 2 identical spade connectors (aside from wire color) for AGC and tuner heater. If neither of the tuner tubes or tuner bulb lights you may have the tuner and AGC spade connectors on the tuner mixed up. I made that mistake in the last month and it didn't damage anything.

I'm thinking that might be part of my problem. Do you have a diagram or a picture showing which wires go where when it comes to the heater and AGC wires for the tuner?

Also another issue I noticed with this TV's tuner was that the section of the terminal strip where the B+ connector goes to was broken so the terminal is just floating in mid air, and only being held into place by the 3 large resistors soldered to it.

Also is the motorized tuning portion of the tuner affected by the 3 tuner connectors or is that independent of that?

One other important connector on the tuner is the IF output. It will be a shielded cable with most likely an RCA style plug on the end of it. So you have four connections on the tuner: IF output, filament, B+ and AGC. If the Sams is new enough, all of the connections will appear in the upper lefthand corner of the schematic.

The motorized tuner mechanism is completely separate from these tuner connections.

The IF Connection is was an obvious connection (the only connector that has an RCA Style connector), same for the B+ Connector the only connectors that aren't as obvious are the AGC and the Filiment connectors, and the Sam's copy I have doesn't list the connections anywhere on the Photofact.

I looked over the schematic again and it did show the connections but it wasn't a style of wiring diagram I was expecting, and it turns out I had the AGC and the Filiment wires switched. I was trying to hook the twin-leads back up to the antenna terminals on the back of the TV and one of the spade connectors broke off the twin-lead connector for the UHF connector.

OK, so I hooked the tuner up properly and I'm still not getting anything out of the tuner yet, no lights or anything, so I wonder if the tuner is just dead on this TV? Although when I tune through the channels with the power tuner, I get a little disturbance on the screen like the tuner is trying to pick something up, but the screen just goes blank.

Have you cleaned the tuner channel strip contacts yet? About a month ago when I was getting the 1964 TV chassis on my Zenith Chancellor going the contacts were so dirty it wouldn't tune anything for a while, and then barely would if you wiggled the knob just right...A thorough clean that took the contacts from black to shiny got it to where it works the first time every time I tune it.

The easiest way to tell which terminal is for heater is to trace the dial light lead...that lead will have continuity to the correct terminal.
Test your dial light bulb too...If it's burned out it's not a good visual aid to tell you if you're heater lead is hooked up right.

I'll take a look into cleaning the tuner contacts tomorrow. It would make sense that the tuner strip contacts would need cleaning, seeing as everything else in this TV was filthy and needed cleaning.

OK, so I took the tuner assembly apart and looked it over and it was actually pretty clean inside not much in the way of corrosion or dirt etc. which is interesting considering the rest of the TV was absolutely filthy inside.

but now I have a new problem, the volume control pot for the TV has a broken terminal, the terminal that the ground wires from the audio coaxials broke off when I was trying to remove it from the volume pot so that I could work on the tuner assembly and also the connector for the ground wires that go to the volume control pot broke off the ground wire leads and I'm not sure if I can source some new connectors like the original ones or not.

Does anyone have a spare volume control/power switch assembly for one of these old Zenith TVs laying around in their parts stash that they could send me? I'm asking because I'm not sure where to look to try and find a NOS replacement power switch/volume control pot for this TV.

OK So I've started digging into the Zenith "Bugeye" TV and the Electrolytic caps listed for this TV are all oddball values that I can't seem to find modern equivalents to without having to go way above or below the orginal capacitor's rated value. One of the capacitors I'm referring to is the main filter capacitor which is a 140 MFD 150 VDC capacitor which the closest standard stocked value capacitor at AES is a 100 MFD 160 VDC electrolytic capacitor, and over at Mouser they had a 140 MFD 150 VDC capacitor but it was almost $30 just for that one capacitor! :no: :sigh: :thumbsdn:

So what did you guys do to replace the original electrolytics in this TV?

Here's a search at Digikey
https://www.digikey.com/en/products/...BKiUrjgYDPFxIA

which turns up for example
https://www.digikey.com/en/products/...2C151S/1245954
150 uF, 160 V, $1.98 in quantity of 1
By the way, the +/- 20% tolerance is way better than the original, which was probably +100/-20%

Of course, you should do a much more detailed search to find the closest reasonably priced to fit.

for filter caps, you NEVER have to be exact. for a 140 MFD 150 VDC cap, for example, i would use something like, 667-EEU-ED2C151 , but that is just me.

I would use a 150 or 180 uF 200 volt cap rated at 105C from Nichicon
or United Chemi-con from Mouser or Digikey (radial leads). At AES a value of 150, 180, or 220 uF at 200 to 450 volts will do as well. These days capacitors are voltage rated
a bit differently than in olden times and its a bit better to go higher in voltage rating if available (i.e. it seems OK to use a 450 or 500 volt cap if the old one was).

As a filter cap it is non-critical value ... in the old days they were usually rated at -50+100% value tolerance!

OK, thanks, I was wondering about that but I wasn't sure, which is why I asked.

Also it turns out I wasted $15 (actually $30 if you count the fact that I ordered the wrong photofact the first time around over at Sam's because for some weird reason the Sam's Index didn't show the 16Y20U Chassis in it anywhere) because it turns out I actually had an original physical copy of the Sam's for the Zenith "Bugeye" TV in my Sam's Photofact stash. :sigh:

If one of the caps is mounted on an insulator its the doubler cap.
You must use a 105 deg or it will puke out mung & fail in a short time.
Its OK to sub in for testing but the 105 needs to go in eventually.
Most new 'lytics come in the following.
1mfd, 2.2, 3.3, 4.7, 10, 22, 33, 47, 100mfd etc
Sub a little over the mfd if need be. The new caps wont be cans.
Pick up some terminal strips to mount them & be sure to cut out
the old cans, not leaving them in circuit.

73 Zeno:smoke:
LFOD !

Yep, seen "The Exorcist" back in the 1970's, , , Now there's a great mental image for a leaking capacitor for ya :puke:

Yes there's one single value can mounted on an insulator in the TV its a 140 MFD 150 VDC capacitor.

The rest of the capacitors are mounted straight to the chassis. So what is it about the voltage doubler circuit that it needs to have a high temp. rated capacitor in that spot?

So does anyone have a spare power switch/volume control for my 23" Zenith?

The reason why I'm asking is because one of the terminals on my switch/volume control broke off (the ground terminal) its a 2 Meg volume pot with a 1 Meg tap and the shaft is about 3¼" long.

See pictures below for the part number and so you can see what the switch assembly looks like.

You should be able to solder a wire on the remaining terminal.
You removed the pot, so it's a little easier.

X2 on dieseljeep's suggestion. That pot is a rare one and would pretty much have to come out of another Zenith.

Just clean the stub down good and get the area well tinned with solder before attaching a wire and is should work fine.

OK, I'll see what I can do. :thmbsp:

X3 on dieseljeep's suggestion. Just be sure the tack area is good and clean so it takes solder quickly. Don't wanta cook the resistive element in the pot.

Or change to a universal 1 meg pot & leave the tap off. It only
there to tailor the bass to the volume. ( boost bass at low vol ).
If its push-pull on / off Malory made a replacement switch.
Depending on shaft it was a KR8M or KR9M.

73 Zeno:smoke:
LFOD !

OK so I fixed the power switch, and volume control pot and I got the backlights going but I'm still not getting anything out of the tuner, in fact just to check to make sure the tuner wasn't malfunctioning I disconnected the IF input from the TV to the VHF Tuner and hooked the IF input to the composite (yellow RCA jack) on the back of my converter box and all I get is a snowy picture with a very faint hint of video activity on the screen. So it looks like the IF Section of the TV isn't working quite right, I'm not sure if its bad tubes or dirty tube sockets, or a badly out of alignment IF section (from someone twiddling the IF Cans when they shouldn't have.)

Does anyone have any ideas as to what could be causing a dead (or nearly dead) IF Section on the 23" Zenith TV?

That's not how it works let alone a valid test. The IF input takes an AM modulated 41MHz ish RF carrier. The yellow composite video output of a DTV box isn't ANYWHERE close to being that.

If you want to inject baseband composite video you can only do that at the output of the video detector diode in the TV (ideal injection site) or points in the video amplifier chain between that and the CRT.

The IF system will ONLY pass IF signal. It will NOT pass composite video.

Ok, then how do people like Shango and the others that I've seen repairing TVs on YouTube use a composite video signal to diagnose the functionality of the tuner and IF on their TVs when they're working on them?

They are using a modulator to put the composite signal on a carrier, either RF frequency or IF frequency.