I just checked L15, L16, and L17 again. They all ohmed out good. See post #43 for the schematics.

Are there any more coils that I need to recheck?

How about L12, L13, L14 and diode M4 ?

jr

It was the video detector diode. I replaced it with a 1N34A that I had.

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Here is where I am using the original CRT that tested on the low side of good. All I've done is twiddle the front and back controls.

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I have another CRT that tests on the high side of good. I'll use this one for awhile during set up etc.

I'm a happy camper.

The 1N64 Germanium diode was bad on my Zenith Porthole too.

I have had a bit of a set back. I was just starting to display a test pattern to adjust the picture when I heard a HV squeal coming from the HV cage. After some trouble shooting, it looks like the FB is the source. I'm going to have to replace the FB. I'm checking on the availability of one locally. ETF lists 2, 1 from 2 different manufacturers. The FB part numbers are:

Zenith = S17233
Thoradson = FLY-52
Merit = HVO-53
Stancor = A-8267
Triad = D-45
Ram = X070
???? = HO-217

Before condemning the flyback verify the drive voltage at The output tube is good, AND that the oscillator frequency is correct. I've seen plenty of good flybacks make death squeals from the frequency being off...they also stop making HV when the frequency is off.

The TV is playing like there is nothing wrong. Just that noise from the FB.

The freq. 15, 850. so that looks good.

Any chance the coil has gotten loose on the core? If it can move you could be hearing a harmonic of the fundamental frequency.

Good question. I checked and the coil is tight. After running the TV for several hours tonight, I felt the coil and it was barely above room temperature and the core was warm but not hot. I could grab it with my hand and hold it for a long time with no problem.
The squeal seems to have diminished some. Barely audible now. I'll check it in the morning and see what happens.

Some sets like to make more horizontal stage noise than others. Some of my tube sets I can't hear the whine, others when audio is muted I can tell they are on from the next room. I had a ~2007 Sharp that was the worst I've ever heard....I could hear the high pitched whine from that clear across the house I lived in back then (distances you'd have to shout at your loudest to be heard across)....That set ran for at least 5 years like that before being donated or sold in working condition.

I'd keep an eye on Horizontal cathode current and grid drive as well as boost voltage. As long as those are within tolerance may as well run it as is...It may get better. If something genuinely is wrong with the fly worst case scenario it will let go eventually. If it stays as is it is long term then it is probably just fine (perhaps a bit annoying, but fine).

If there were any issues with FBT there would be obvious symptoms on screen. I would have a poke around while the set is running with an insulated prod (plastic pen perhaps) to see what is making the noise. It might not be the FBT at all. Gentle pressure on each component should reveal the culprit. In Aus our line frequency is 15.625 Khz and I find I now have a notch in my hearing at that frequency.

The noise has almost completely gone. Though I'm keeping an eye no ear, on it.

The last few days have been spent on some details.

I polished up the E-Cap cans and installed them.

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I then repaired the broken shaft on the fine tuning mechanism. I found some 1/4 inch phenolic rod on eBay and bought several 6 inch pieces. The guy was from Fort Worth and they arrived the next day.

After I traced out the positions of everything I tapered the one end using my disc sander at first then my drill press to true it up. I then cut it to length and cut the groove for the keeper. To do this I used my battery drill clamped to the bench. Then turned it on and cut the groove with a hacksaw blade. Took all of 3 minutes. After cleaning up the pieces I pressed them into position. I installed the shaft and the keeper. Then restrung the dial cord.

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