90's color tv help

[ProAc_Fan]

My father in law found a Zenith 27" color tv by the side of the road. He repaired the broken power cord and it now powers up fine. The sound quality is also great. The only problem now is with the color blue. The red and green appear to be fine. Where would you start to troubleshoot this malady? The set is a mid 90's System 3 set.

Mike

[Rob]

ProAc,

See, it was curbside for a reason! :) Where would I begin troubleshooting this set? "I" wouldn't have picked it up in the first place! ...SINCE IT ISN'T A V-I-N-T-A-G-E color TV. ;) Now if that were a modern WEGA 40" Direct View I'm sure I'd have to confiscate it to set an example to others for abusing this newly created vintage color TV forum. ;)

If you want to try to troubleshoot there are others much better acquainted with fixing SS TV's than I. I think I'd get an o-scope and poke around the blue video amp which is likely on the CRT socket and see if there is trouble there. If there is blue signal then the CRT could have a dead gun. Oh, yeah, see if the 3 filaments are glowing (if it has 3). See, I don't know much about this newfangled stuff. :dunno: If there is NO blue video signal then you go progressively farther back in the circuit which carries the blue signal.

Careful, there are high voltages inside a color TV waiting to give you an unpleasant ZAP. If you don't have a basic understanding of the workings in there, don't take the back off.

Rob

[kc8adu]

the high failure rate of crt's in these is what sunk zenith.
i would check for blue video amp problems though because green seems to be the first to go on these.
lack of blue=yellow picture.
lack of green=purple or violet picture.

[kc8adu]

make sure you have an isolation transformer if you go poking around with a scope.
you should have one anyway as these new sets are hot chassis.

[andy]

If it was made in 1993 or later put it back at the side of the road. These sets had the worst CRTs ever made. The 1993-1994 ones had 100% failure within about 3 years of normal use. Later ones were a little better, but not much.

[Eric H]

Mike, I found the answer to your problem :D

[kc8adu]

that looks like my dumpster after a shop cleaning!
:)

[julianburke]

These sets were notorius for their bad picture tubes. They would lose a color and not necessarily a bad blue driver transistor.

[MRX37]

It's a mid 90's 27" Zenith. The picture tube is probably shot. If you have a CRT tester, you could check for emission levels/shorts, etc.

Try turning the color down to nothing and see if it has a good black and white picture. If the picture is tinted in black and white, the tube is shot.

EDIT: Wait! this thread's from 2002! Why was it revived?