Zenith Console combo

[DaveWM]

so anybody run into the screen that loses contrast toward the bottom of the screen (a progressive loss from top to bottom).

just hoping to get some pointers..

[DaveWM]

went out to hook up the scope and start trouble shooting the pic issue, power up, PERFECT pic.

the only thing I did was attach a lead to pin two of the video amp.

So I will clean up the garage, button up the back and get a pic.

Not sure why but I aint complaining.

the vert is a tiny bit jumpy, not as bad as my other zenith 20y chassis.

So now I will need to decide if I should pull the chassis or not.

the only issue I have is I know about those old paper caps HV hard shell tube caps. I am tempted to leave well enough alone as I know there is always a risk when disconnecting old plugs etc.. that something could break.

So I will button it up, get some pics, see if the picture contrast at the bottom of the tube returns and see if the vert jump settles down.

The picture color and focus is excellant. Needs a slight dynamic convergence adj. I may replace the diode pack on the board just because its old and I assume the Se's are getting leaky.

one of the reasons I want to pull the chassis is its just so damn dirty, WAF comes into play (if she happens to catch me with the back off, and its in the house).

[DaveWM]

disconnect lead get ready for pics, turn on set, contrast problem has returned.

turns out the video amp tube must have a dirty socket issue, wiggle that vert amp tube and all good again. I guess I was on the right track to check there 1st

Just another reason to pull the chassis and do a though cleaning, including the sockets.

[DaveWM]

the AGC seems to have a bit too much AC ripple in it, no hash but ripple.

Not sure if that could account for the overly sensitive AGC adj. Anyway I will end up pulling the chassis and checking all the filter caps. No audio hum and no hum bars in the pic. I should check the B+ for ripple before I pull it out, IIRC there is a big power resistor that sits on top of the chassis, one side of which connects to the choke and is where they sams show the ripple (2v).

[DaveWM]

some pics, the last two show the need for a lin adj and the pie crust effect that happens when the yoke is squealing, only last for a few seconds. I need to check purity so when I do that I will make sure the screws on tight that holds the yoke in place.

the pie crust is on the last shot of the womens face

[DaveWM]

micro panic time...

I am cleaning up the contacts, including the CRT cathode plug in connections.

Of course I put the red gun to the wrong post. After futzing with if for 30 min I realize my error, put it back all fine now, except for my messing up all the screen drives and controls trying to get the red to work.

I checked the CRT no damage, excellent tracking and good emissons, so at least I did not hurt anything but my wits.

Oh well it needed a good setup anyway, now I have a reason to do from scratch.

still has that annoying high pitched un even noise at start up, I cant be sure where its coming from. I tried touching the fly and the yoke with a wood stick to see if I could affect it, but no joy. I wonder if it could be coming from the pin cushion? the thing is its also gets some noise into the pic (the streaks). I will keep running it and see if it improves. Its not a big deal since it always stops and does not come back after the inital warm up.

[DaveWM]

boy this thing is kicking my butt. The new HOT tube fixed the squeal, but then I lost HV regulation (would bloom too easy, and the HV adj did nothing. Wide open with no beam current would be about 24k, but would drop to below 20k and be moving all over the place with the beam current. I also lost width. So I tried ANOTHER 6JS6 HOT, plenty of HV now, in fact all the way down and even with a bright screen its 25-27kv, too much really. Not sure I will try a couple more HOT's if I can find (I have a few pulls to try) but I may end up having to buy one. Oh and the width problem went away. Still now squeal so that is good. I may but that squeal tube back in and see how it goes.

I tried the purity setup, the yoke did not seem to go back far enough to get the red blob in the middle, so I just fiddled with the purity tabs to get the red centered as best as I could (most of the screen was red) then pushed forward to get it to cover the whole screen in red. Color purity looks good now. still some dynamic convergence to work on.

Still have not pulled the chassis to replace those few HV film caps.