Picture Problem with the Zenith - Videokarma.org TV - Video

mwplefty · #1 10-14-2010, 05:40 PM

I just hooked up the APEX converter box to the 1976 Zenith 4-Tube Hybrid. I turned it on to channel 3, scanned for channels, and all was well. (The colors were a little messed up but that was the least of my worries at the time). I watched it for about 30 minutes or so and turned it off.

Just for fun, I thought I would turn it back on again, and this was when the picture crapped out on me. The sound was perfect and the channels were changing fine with the remote, but the picture wasn't showing up. It wasn't snowy or anything like that. It was just black with several white lines running horizontally up and down the screen. I adjusted just about every switch on the outside of the set, fixed the rabbit ears, but nothing worked.

Could it be as simple as just adjusting the AGC switch? I doubt it's the converter box itself considering that I still get sound and the remote is functioning properly. Or maybe I was watching it too long and it just needs to sit for a while?

What does anyone think?

DaveWM · #2 10-14-2010, 05:43 PM

with no signal is there raster?

On my zenith the AGC can black out the tube, but I dont know why it would just get out of whack.

mwplefty · #3 10-14-2010, 05:46 PM

[QUOTE=DaveWM;2984928]with no signal is there raster?

Yes. I'm getting the horizontal lines rapidly moving up and down and across the screen.

Let me take a picture. That might help a lot.

radiotvnut · #4 10-14-2010, 06:22 PM

I wouldn't put it past the converter box to be causing the trouble as those APEX boxes are total JUNK! Try a VCR or DVD player and see what happens.

ctc17 · #5 10-14-2010, 06:31 PM

I will second the APEX boxes are TRASH.

Although it sounds like it may be a sync issue inside the set, try the box on another set and see what you get.

Pix would be good.

mwplefty · #6 10-14-2010, 06:49 PM

Quote:

Originally Posted by ctc17

I will second the APEX boxes are TRASH.

Although it sounds like it may be a sync issue inside the set, try the box on another set and see what you get.

Pix would be good.

I did get a picture for about a minute since then. But of course, as I was messing with the color and tint knobs to steady the colors on the screen, the picture disappeared again.

So even though I get sound, it could still possibly be the converter box that is ruining the picture?

mwplefty · #7 10-14-2010, 07:15 PM

Here it is connected to the converter box on channel 3:

ctc17 · #8 10-14-2010, 08:51 PM

What happens if you turn the horiz hold on the back? Can you get the bars to float side to side?

miniman82 · #9 10-14-2010, 09:15 PM

I know you're young and everything, but how about you RECAP THE SET LIKE I SUGGESTED BEFORE ASKING PEOPLE ABOUT A PROBLEM THAT ALREADY HAS A SOLUTION....

I don't mean to be corse with you, but your RCA set didn't have anything wrong with it either, your inexperience is biting you in the rear. Do the cap job, before the set explodes and burns your father's house down. Sheesh.

jpdylon · #10 10-14-2010, 11:07 PM

Your screen shot looks like the oscillator on the tuner is off. Did you switch channels and jiggle the channel selector knob to see if the symptom changed any? Turn the AFC off and try to fine tune it in.

Make sure the box didn't switch outputs on you (ch4 instead of 3)

....and yes - if you plan to use the set, restore it - or you're going to have a paperweight when the smoke gets out.

ctc17 · #11 10-15-2010, 02:05 PM

Audubon has a set that did something very similar. Putting an old set back into use usually brings a second round of infant mortality. The set may wake right up and play for a few days then something will fail. After a few weeks of use and fixing the problems that appear during that time they seem to be fairly reliable.

I have been through about 40 old sets now and they all seem to follow the same pattern.

As far as these 4 tube hybrids...they have crappy caps, and the ICs fail along with trippler /focus board problems.
If I came across one of these I would pass it buy

mwplefty · #12 10-15-2010, 05:43 PM

Quote:

Originally Posted by ctc17

Audubon has a set that did something very similar. Putting an old set back into use usually brings a second round of infant mortality. The set may wake right up and play for a few days then something will fail. After a few weeks of use and fixing the problems that appear during that time they seem to be fairly reliable.

I have been through about 40 old sets now and they all seem to follow the same pattern.

As far as these 4 tube hybrids...they have crappy caps, and the ICs fail along with trippler /focus board problems.
If I came across one of these I would pass it buy

It's funny that you say that because it worked so well at first and then, all of sudden, the picture goofed up. I feel that if I let the set sit for a few days and maybe clean it, something might happen. (I was told that was a major issue with my RCA; it was a heavy smoker's set and that messed up some of the connections).

The reason why I didn't do anything with the set at first was because I didn't want to play around with something that actually worked for the most part. Then when I finally try to steady the colors, the picture disappears.

By the way, I checked the chassis number (it was located on the inside cover of the set). It's actually a 1972, not a 1976.

ctc17 · #13 10-15-2010, 06:10 PM

nope it wont heal. Its going to require some corrective action. Time to dig in and get your hands dirty.

miniman82 · #14 10-15-2010, 06:21 PM

Cap replacement, do it!

freakaftr8 · #15 10-18-2010, 03:59 PM

Looks like IF section to me. I agree. Do a full recap. You will thank us for the suggestion. And the raster will appear a whole lot crisper and vibrant as well. Old caps have a tendancy to wreak havoc on all the other parts in your set as the MFD ratigs increase.