hakaplan
06-12-2008, 12:14 PM
I have a Zenith color tv from 1996, model SR2768S, serial: 621-42031090.
The blue is gone. I replaced the blue output transistor. No improvement. Don't know where to go now. There is an blue adjustment pot on the board near the transistor--should I mess with that? Would a pic of the board be helpful? It looks to be in good condition--all solder joints nice and no broken traces. Any ideas? Thanks very much.
hakaplan
06-12-2008, 12:27 PM
I wouldn't rule out the picture tube. Zenith CRTs from the mid 90's had serious quality problems. Did it happen suddenly, or gradually?
Hard to say. I think suddenly. Didn't watch it for a few years, then recently noticed that I didn't see blue. It may have been unknowingly on for a long time--like a month--my wife had turned off the cable box, but neglected to shut off the tv. Could that have caused it?
radiotvnut
06-12-2008, 12:29 PM
The CRT would be the first thing I'd check as those Zenith CRT's from that time period are some of the worst ones ever made. They will lose emission and/or intermittently short and blow parts in the power supply and/or video output circuit.
Also, there are some driver transistors ahead of the output transistors. These are located on the main chassis. I've seen those fail due to a shorted CRT. You can replace the transistor and it may work for a week; then, the CRT will arc and blow it again.
I used to get these sets with bad CRT's from a local Zenith repair shop when they were only 2 or 3 years old. Sometimes, I'd get lucky and find an older one with a good CRT and take 2 sets and make 1. '90's era Zenith CRT's were bad with '93-'95 being the worst.
hakaplan
06-12-2008, 12:35 PM
Well, short of replacing the CRT, is there any remedy that I could perform. I can solder, but I have no diagnostic knowledge with tv. Otherwise, I'll chuck it. Sad, really, because it's so nice and big and works fine otherwise.
jblmar
06-12-2008, 12:36 PM
Try switching the leads to the Red and Blue transistors. If you now have Blue and no Red, the transistor or its associated components are bad.
Ron
JohnAdams
06-12-2008, 05:14 PM
If you don't repair it and it has a 1298-03 crt module, I would be interested in it. The SR2786 used that module but I don't know about the SR2768.
Thanks
hakaplan
06-12-2008, 10:26 PM
If you don't repair it and it has a 1298-03 crt module, I would be interested in it. The SR2786 used that module but I don't know about the SR2768.
Thanks
I will check.