Zenith 19EC45 Vertical Problem?

[jblmar]

I agree. There are caps soldered to wires behind the chassis.

Ron

[jblmar]

Hi all,
Here's an update. I haven't had a chance to look at the set for the past few months. The set now works! I was surprised when the problem occured while cold and functioned properly when warm. Intermittent problems are usually the opposite. I still believe that there is a bad electrolytic capacitor(s).
Thanks to all for helping out. I'll keep an eye out and report back.

Ron

[jblmar]

Hi all,
Just a follow up on the set. Thanks to all for your input.
The problem has returned! I went through the PCB and found 2 capacitors that measured 0 mF. I replaced one on the output board. I need to get the other on the Raster Blanking board.
The voltage regulator (Q 201) checked out o.k on diode test and voltage test. Next step was the vertical output transistors for voltage.
A cold solder was found on the output board. Resoldering returned the proper bias voltage to Q707. All measurements on the board are now correct. On to the next board(s).
I'll replace C908 on the Raster board and post the results.
I need to go through all boards and wire soldered components in the set. If 2 caps are bad, there's more.
This set is very easy to work on. I can't setup the 'scope for lack of room to work. Have to do it the hard way.

Ron

[holmesuser01]

And one more comment: That is probably the best 19" TV ever built. That has the 19VDZP22 HyperFocus tube in it. Black matrix and very nice phosphors.

Charles[/QUOTE]

Its also one of the heaviest sets I've ever hauled around, too!

[jblmar]

Thanks Charles.
Repaired the problem last night. C908 measured 0 mF. That cap should ground the Vertical Blanking transistor to turn it on. The transistor wasn't conduction.
Thanks to all for your help and input.
A special thanks goes out to JSTOUT66 for his generious offers re replacement boards for this set. If anyone needs replacement boards, JSTOUT66 is the person to contact.
Charles. The picture is fantastic. This is the 19EC45 25" Picture Tube. Cleaning of the tuner along with all pins on each PCB will result in a great picture.

A note on handling the Vertical Output PCB. It's very easy to touch the Vertical Centering or Size VR while handling the PCB for inspection. Upon completion of a repair/inspection, check to see that the picture is centered while observing a program containing CC pulses. Watch the TVs tuner, not a tape or disc. Most CC is either on the top or bottom of the screen, hidden behind the frame of the Picture Tube area. When I put the set back together last night, the CC pulses were visible. A slight 'touch-up' of the Vertical Centering control fixed the problem.

Ron