A Bad Digital System 3

[jstout66]

A fellow AKer told me about a Digital System 3 that was in a thrift store in my area.
I just wanted to vent about those short lived "bad" Zenith picture tubes of that era.
I went to go look at it, and figures.... a high end model with "Sound By Bose", a cabinet style I loved, the set was clean, and at a fantastic price.
Go figure it had the worse picture of all the sets there. It wasn't the worse I've seen of those bad tube Zeniths, BUT had bad convergence and a horrid pix on Black & White.
Too bad it had that crappy tube in it. I'm not familiar with the digital line. How were the chassis, and were there better replacement tubes for them?

[radiotvnut]

A friend has a 31" digital system 3 in a console cabinet. I think it's an '88 or '89 model. It has all sorts of jacks on it and would receive teletext information. He said he gave $1600 for it and it was a store display. Once, it went dead and all it needed was an AC fuse (lucky me). Later, the vertical started to stretch at the top and the tube started going weak. I rejuved the tube but left the vertical alone because he said it wasn't bothering him. The tube quickly started falling back down again. That set was very packed inside and I think the main module was a 9-700. Since the board was shielded and hard to get to; that board was very hard to service. That set has been serving as a stand for another plain 27" TV for the past 6 or 7 years.

I once had a little newer 27" digital system 3 with the Bose audio system in a table model case. The CRT was 100% DEAD and the set had power supply problems. Due to the bad tube; I junked it.

Even though these sets are a pain to work on; they had some nice features for their day and made very nice pictures when the CRT is good.

I don't know if there was a better tube made for those sets. Around '94, someone gave me a '92 ordinary 27" Zenith that used an A68ACT00X tube. I replaced the tube with a rebuilt OptaChrome (IIRC) brand and it only lasted a little over a year before it shorted and took the power supply with it. Every now and then, I'd salvage a better Zenith tube out of a junked '80's console. That was about the only way I could fix a '90's Zenith with a bad CRT.

[andy]

The CRTs in these sets aren't known for being bad. They discontinued the Digital line before the really bad CRTs came out (in late 1992). They aren't like the Chromacolor CRTs for long life, but they aren't too bad. The problem is that they are 15-20 years old so a lot of them will have weak CRTs due to age. The convergence was probably bad due to the yoke slipping out of position. The yoke's exact position is critical to the edge convergence.

If it's a 27" set, then any 80's 27" Zenith CRT will work in it. Just don't use anything newer than 1992 even if it's brand new in the box. I've put RCA CRTs in these, but the convergence wasn't very good.

Note that any CRTs bigger than 27" was not made by Zenith. You could probably find out who made the CRT by the EIA number.

[drh4683]

If 1992 was the start of zeniths "bad" years for CRT, when did they become "good" or "better" again? I dont know enough about the 90's zenith sets. Ive worked on very few of them. How long did those tube last before they started to have problems? Its really dissapointing that one of the great names in US electronics let quality slip like that.

[andy]

They were better by 1995 (they just went weak rather than shorting), but they were still not very good. The problem was completely solved when they closed the plant.

[Celt]

Originally Posted by andy

The problem was completely solved when they closed the plant.

[radiotvnut]

Originally Posted by drh4683

If 1992 was the start of zeniths "bad" years for CRT, when did they become "good" or "better" again? I dont know enough about the 90's zenith sets. Ive worked on very few of them. How long did those tube last before they started to have problems? Its really dissapointing that one of the great names in US electronics let quality slip like that.

During the late '90's - to around '02, I was given MANY 90's era Zenith's by the local Zenith dealer / repair shop. 95% of these had some sort of CRT defect. It seems like the '92 to '95 models would short and blow up the power supply. These would often be weak at the same time. They did get a little better after this; but, not much. I still saw plenty of '96 models on up that had bad CRT's. I saw several '97 and '98 models that had good emission; but, they would arc and take out one of the video driver transistors. A new transistor might fix the set for a week or two - then BAM! I think '99 is the newest Zenith I've seen with a bad CRT. The age of these sets was anywhere from 2 to 7 years old by the time I got them. I've seen a couple of '99 Zenith's that had the bonded yoke style tube that looks similar to what's in a Thomson RCA set. Those tubes were good (at least the ones I saw). My friend that used to work at the Zenith shop said some of the newer ('99 on) Zenith's had Philips tubes in them. It's a shame that a company that once made "last forever" tubes ended up making tubes that were doing good to last out the warranty. Those were the worst tubes I've seen. If I ever see another one of those Zenith's, it will be too soon!

BTW, that dealer is now out of business. Couldn't compete with walmart and other "discount" stores. I will say that I got a few good '70's Zenith's from them. Looking back, I should have kept them!

[MRX37]

I can say for certain that some 1997 Zenith tubes are junk as well. Color bleeding, green tint that shows up when the picture is bright, no convergence in the corners to speak of...

98 Zenith tubes are better, but not by much. No color bleeding in my 1998 Zenith yet, but the convergence in the corners is starting to go...

[radiotvnut]

One other bad Zenith tube issue I remember is that the brighter areas of the picture will go out of focus. It will look like a blurry band going across the screen. Sometimes, turning the contrast down will do some good.

[kx250rider]

Originally Posted by jstout66

How were the chassis, and were there better replacement tubes for them?

My personal advice:

1) Scream like a little girl as soon as you see a Digital Zenith

2) Run as fast as you can, away from the TV

I don't think I recall EVER repairing one. Many attempts, yes, but repair, no. Those replacement modules didn't even come with the chips! you had to buy those extra. They had TERRIBLE intermittent conditions, such as deciding to lock up and go to max volume, or just seize up and need to be unplugged, etc etc. It was a nightmare.

Toshiba also built a digital set about the same time, and it wasn't bad at all.

Charles

[site123a]

Before I gave my Zenith away, it would flash brightly in the middle from time-to-time...

[Whirled One]

Question: Did the quality problems with Zenith CRTs in the early 90's run across all screen sizes, or were they specific to the 27" tubes..?

I've seen some 27" Zeniths with bad CRTs in thrift stores and the like, but I guess I haven't seen so many problems with the 25" and smaller Zeniths. Perhaps it's just luck of the draw though. I've got a 1993 25" Zenith (a rather plain Sentry 2 set) that I bought new in '93 and it's always been fine. Also the CRT is just fine in my 1989 20" Digital System 3. The little 9" and 13" Zenith color portables that I enounter seem to always have good CRTs as well (though at least the little 9" cube-shaped Zeniths *do* often seem to have problems with bad solder joints).

[andy]

The 27s were the worst, but the 19-25 were almost as bad. They were still good in 1989 although the quality seemed to vary. Zenith CRTs seem to either look perfect, or are completely dead. I never saw many that were in the middle.