I am working on a 1993 Zenith AVI series, SL2784BT, with a intermittent CRT or a CRT driver module, mounted to the crt socket. ( 1298-03). I have seen a number of negative comments about Zenith CRT's of this time frame, but this CRT has an EIA code of 1101 on it. My memory from the old days,60's, was that 274 = RCA, 343 = Zenith and 1101 = Sylvania. That is why I wanted someone to verify that this set doesn't have a Zenith picture tube. I hate to pay LG $88 for a new driver module and find out that the crt is the problem. You can lightly tap the driver module or the tube neck and the blue quits leaving a green screen. Over the years I have seen mention of the "green" screen and most responses were to replace the module. Seems like it is always the blue that is lost and not the red or green. I have the 32 inch version of this set and never had a problem so if I scrap the 27" set, I will save the modules since most will interchange, except for the crt module.
If some one has a scrap 1298-03, I would be glad to buy it. It seems like that made 3 versions of the 1298 based upon which size picture tube was used, 27", 32" or 36". That keeps me from swapping the modules between the 2 sets I have to see if the module is really the problem.

If tapping the module affects the picture, it's probably a bad module.

Zenith CRT's from that era tend to get dim, have color bleeding, and the corner convergence is shot.

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I would resolder everything on the CRT driver board. I have seen loose connections in this area cause the symptoms you describe (not just in Zenith sets). It's usually the socket, the cables connecting the CRT driver board to the main chassis, any power resistors, or the video output transistors that need resoldering.

If that does not work, suspect the CRT. Is it an A68ACT00X? That one was really a problem in the '90's.

Is your chassis one of those with the two large modules? One for signal and one for the power supply and sweep circuit.

Radiotvnut: The CRT is A68AGD00XX.
Yes, 2 main boards, 9-1235 "Main" and a 9-1268 "Sweep".
I plan to check all solder joints. only problem is that the back side of the board has a lot of tiny SMD's.
MRX37: the crt socket is in the middle of the driver module, thus when you tap one, you tap the other.

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Andy: Tube is original, June 28, 1993. I ran the set with no problem and good picture for about 5 hours last night.
The last 10 years this set has had limited use in a bedroom. I bought the 32" version in 93 when a friend bought this one. My 32" Zenith AVI has been perfect and I would put it up against my 36" Sony Wega (2001) any day. Just from looking at the list of models that use the 1298-03 driver module, this chasis may have been one of the last "high end" Zeniths.

Andy: Tube is original, June 28, 1993. I ran the set with no problem and good picture for about 5 hours last night.


Definitely a loose module.

You may be lucky. Zenith may have screwed up and put a good CRT in your TV. Rare for a 90's Zenith... I'd hold onto that one if I were you...

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I found a '97 Zenith that was only 2 or 3 years old at the time. It had no green due to a defective green driver transistor. A new transistor brought a beautiful picture back to the set and I was very happy since nice 27" sets would bring $125+ back then. I sold the set to a friend and it played two weeks and then the CRT arced and blew the green driver transistor again.

I've had the same thing happen when I'd repair the power supply in the '93 and '94 models. It might play 1 minute or a couple of weeks before the tube arced and blew out the new parts.

It finally got to the point where I wouldn't go any further if I saw those parts burned up in a Zenith.

I am going to hang on to them. I don't know what the exact deal was, but around 1995 we were selected by A.C. Neilsen for monitoring and each tv would be hooked up to a central computer, all activity monitored and it would phone home each night. Well, they got both bedroom tv's set up and the second night they were ready to finish up and could not find instructions as to where to tap into the 32" Zenith to know what channel it was watching or if it was getting a video signal from a vcr. They called their tech support in Colorado and were told they could not monitor the set because it was "digital". Obviously that "digital" was different than what we call digital today, but I guess I had something of a novelty. I do know that you can bring up a service menu and there are over 100 items you can adjust or screw up. This may be a newer version of the "Digital System 3".

PS:
this set doesn't blow anything when it looses the blue and goes green. Just tap it and it's working again. Last night, I could never make the blue stay off. If I did get it to quit, it was back in a few seconds. I am going to resolder as many connections as I can and go from there. Thanks everyone for the responses.