Zenith marketed the access plate on the bottom as the Service-Saver Chassis because it allowed service from the bottom of the set without having to remove the chassis. Components replaced, or measurements taken with the set running, tipped on its side.

With the IF Module removed, can you turn up the brightness and get a raster?

Yes, you can connect your generator 50 ohm video output to C1 with the IF module in the set. Rock or position the tuner slighlty to mid-channel, or you can remove the IF in cable.

Google "Servicing a 1974 Zenith 19DC12 4 tube hybrid color tv" you might find this YouTube interesting. No connection to the author.

After all the times I've been inside the set I never noticed that there are 4 threaded inserts in each corner. I've never see an Avante with anything other than the plastic base, so I wonder what they are for. I was thinking of making some legs and screw them in so I can take off the base and open the bottom and not have to put the set on its side.

Okay, I'm going to give the generator to C1 with tuner disconnected as I am unable to set the tuner between channels as it's motor driven.

I'll also try upping the brightness with the IF removed.

Connecting to C1 with tuner, generator doesn't bring up anything useful. I can tell the generator is doing something as the screen changes a bit as I set the output level, but it never brings up anything even close to a pattern. With the IF removed, no amount of brightness setting brings up any raster, etc. I'm going to go over my pics of the underside and trace exactly where the IF out goes if not directly to C1.

I tried testing the voltage on the video out of the generator, but it only went up as I moved the output level and then dropped to 0 after moving it. I think I'll connect it to my scope and see if it actually putting out a composite signal.

If I'm not mistaken, I should be able to connect the center of a video out from my old DVD player to C1 and the outer to ground and get an image? I'm not worried about and if it works, I can let it go into screensaver mode as that really shows the jailbars.

I watched the video. Some interesting content. I've tested my CRT with 2 separate testers and each one shows it good. While I can't get a red or green line, I can get a faint blue line. However, if I do greyscale outside of the setup with a greyscale ramp, I can get very strong colors from each gun and good brightness. The thing I haven't been able to figure out is the gain taps. I understand they work through a series of resistors to help remove color from the white parts of the picture. If I am understanding the schematic correctly, if you pull the tap off, it disconnects the video output to the crt and that removes the 142V. So why, when I pull the red tap in setup do I get a bright red line and lose it when I put it back? Like I said, if I understand the schematic, why red line with 0V and no line with 142V

Rejuvenating is risky from what I understand. I don't want to run the risk of damaging the CRT.

There was one thing I didn't fully understand from the video. When he was reading voltage from each of the resistors, what exactly was he seeing that pointed to the CRT's blue gun? One side of all of them seemed to have the same 26xV and the other side of each had lower, with blue not matching what red and green showed. Not sure how that translates to a bad blue gun.

I'm posting a couple of screen shots. I have to admit this is the best the set has looked so far. These pics don't do it justice as I am getting better shots from the camera adjustments advised by others, but they are still a far cry from how good it looks in person. Got quite a few compliments on the image quality. The youngsters didn't know a CRT image could look this good. They thought all you'd see is large scan lines and blurry images. :lmao:

Tested the CRT again today and it tests as good and the image produced (color, brightness, contrast) seems to agree. So the inability to bring up lines in setup doesn't seem to be the fault of the CRT. Oh, and I got the greyscale set so well, I didn't have to touch the gain taps at all this time. Usually I had to move one and deal with the whites not as white as I'd like, but now they are pretty much dead on. Not too warm and not too cold.

Now if I can just get rid of the darn jailbars, I'd have a damn near perfect set.

What are the odds the jailbars are from the flyback? Reason I ask is I can get an NOS replacement for ten bucks. Even if it isn't the cure, are flyback usually something that hardly ever needs replacement, so a spare isn't necessary?

New question. I don't want to pull it again, but I find that the SM doesn't have anything on my tuner setup other than the remote board. I have no clue if the non turret schematics are for mine or not. I had it out months ago to fix the power on/off issue. I replaced all the trigger caps and other electrolytics on the board and it fixed the issue. I was just going over some pics I took and noticed that there is another board in the tuner/remote assembly and it has three electrolytics on it. I don't know if it's a board connected to the tuners or the board used for the channel tuners on the front side.

While on the subject of tuner, does an OEM IF module come pre-adjusted, or is that something that is done once installed and connected to the tuners?

Also attaching a pic of a piggybacked resistor that came in a batch of Zenith parts I got. It came in a plastic bag with no real indication on what it meant for.

The top resistor looks like 820 ohms +/-10%.

https://circuitdigest.com/calculator...ode-calculator
decodes the 5-band resistor as 1.02 ohms +/-4%, which makes no sense to me.

Where did this batch of parts come from? Kind of seems like someone's bench sweepings unless someone can tell us what the 5-band device really is.