Sound troubles on zenith 19z32q chassis

[jpdylon]

This set has been somewhat of a challenge as something new seems to fail every time I use it.

The set has been completely re-capped and I had to thoroughly clean all the tuner contacts to get a decent picture and sound. This was back in late november.

It had the typical intercarrier buzz that alot of zeniths suffer from - but the sound was undistorted and had plenty of volume. Just two days ago my sound disappeared, but left the intercarrier buzz behind. No sound, just buzz that varied with the scene. This was a sudden failure.

I determined that the audio portion of the set is working by injecting a signal into the audio detector, however the sound carrier is not getting to the detector from the IF strip.

At this point, I am unable to tell with certainty that the problem is in the tuner or the IF strip. However, when the fine tuning is turned through its short range the buzz changes drastically and blank channels reveal that there is white noise so I'm more likely to believe the problem is in the tuner.

I hate to tear the tuner apart again because its somewhat of a pain to get to the wiring and tube sockets. It has a strange oscillator adjustment that looks like a flat head screwdriver sticking up out of the tuner. I don't have an adjustment tool for this.

I know this is a silly question, but is there any easy fix. Any ideas?

[kx250rider]

As you point out, Zeniths buzz. They always have buzzed, even when new and on a roof antenna in a perfect environment. Add to that CATV and closed caption subcarriers, and you gotta granddaddy of a buzz! Even Chromacolor II sets buzzed sometimes.

As far as trying to combat it, I never found any total success other than VERY CAREFULLY adjusting the audio detector slug, and fooling with the buzz pot. Then you get it perfect on most channels, and one channel will buzz you out of the room.

My advice to anyone with a vintage Zenith as a daily watcher, is to pick the sound from a cable box or VCR, to a stereo. My flat chassis 25DC56 buzzes on anything with a text crawl at the bottom, but I've been used to it since I got the set at the Salvation Army store in '81.

Charles

[jpdylon]

that's what I ended up doing with the setup, just wanted to see if I could at least get the sound to work.

oh, and it turned out that I had overlooked the buzz pot - which had a dead spot (high resistance) If I turn it to one extreme you can just barely hear the sound over the buzz, turn it any other way and its just buzz. Measures about 4 meg in the dead spot. Putting a 250k in place of the pot makes it work so i think a new control ought to do it.