Another newer Sony with issues

[jhal]

I have a Sony 31" trinitron that was made in June of 1996. My family had it since new and gave it to me. The problem is, the picture is in black & white. It does this on all inputs and through the antenna/cable connection. What's interesting is, the on screen graphics are still in color while this is happening. That leads me back to something in the input stage and the color circuits are ok. Also, sometimes it will work fine for the first 5 or ten minutes of operation, then it goes black & white. I was thinking maybe there is some cold/bad solder connections on the board somewhere. This is a very heavy set (as you probably know), so that has prevented me from taken it to a service tech. I have audio repair skills, but have limited television knowledge. I know the proper HV procedures for servicing, and have done repairs before, but I don't know where to start on this somewhat new set. I may not even mess with it since you can get CRT type sets for nothing or near nothing now that people are upgrading to Hi-def. I just want some suggestions in case I decide to tear into it. It was an expensive set when new (weren't they all?), and it does have a beautiful picture when it is working correctly. I would just like to save it and put it to good use. Thanks for any help, John.

[MRX37]

I know that if the tuner is off, the picture will lose its color.

[jhal]

I also have black and white through both the rear panel and front panel composite and s-video inputs. Whatever the signal goes through before the graphics are added in the signal flow is where it loses color since the on screen graphics are ok. I have good colors when bringing up all of the menus on top of a b&w picture.

[radiotvnut]

Loose connections are a suspect. Try tapping the board with the insulated handle of a screwdriver and see if you can make the problem act up. If that does not work, try spraying parts on the PC board with freeze spray. Otherwise, you may have to obtain a schematic and trace the circuit with a scope and/or multimeter to find the problem.

While you've got it apart, resolder the horizontal drive transformer. That's the little transformer connected to the base pin of the horizontal output transistor. This transformer is bad to have loose connections and can take out the HOT as well as the power supply.

That set is probably worth spending a little time on if the CRT is still strong. Those mid '90's sets seem to be a little better than the current cheap CRT junk.

[jhal]

Yeah, it produces one of the most beautiful non hi-def pictures I have ever seen. That Trinitron tube with it's heavy inner frame on which the wires are tensioned makes it as heavy as much larger sets. Moving it is definitely a two-man job.

[MRX37]

Eh, one guy can move a Trinitron that big. I've done it... It's not exactly a safe thing to do, and it makes you very very sore, and regretting that you were stupid enough to lift that heavy son of a bitch by yourself...