Help repairing a 95 Zenith please.

[Eric H]

One of my Coworkers brought me his 1995 Zenith with a problem.

On power up it looked like the top had some foldover and was stretched out, (note that I had no signal so I couldn't really see what was going on for certain) it also looked like the sides were pulling in just a bit. It doesn't do it all the time however and I wasn't able to get a picture of it acting up.

I took the chassis out and soldered a bunch of stuff, even though it looked fine, it's still doing the same thing.

I really figure it's a cap in the vertical going bad but I have no idea which one, I was hoping one of the experts on modern sets would recognize this problem and know what to do.

The model is SR2568S, I have some pictures of the chassis if it helps any.

I know it's just late model BPC but the tube looks strong and if it can be fixed simply I'd like to be able to do it for him.

Thanks much.

[Zenith26kc20]

Look around the middle of the set. The power supply regulator is mounted on the heat sink near the middle. Change the electrolytics in the section the IC faces. They dry out and B+ starts to vary and this van cause a number of problems. A ESR meter helps plenty on these sets.
Also, on the right front as viewed from the rear of the chassis is the vertical output IC. This develops bad solder connections. Be careful not to bridge any pins as it will blow the IC.
Good luck.

[Eric H]

Would these three highlighted with green be the ones to change? including the main filter?
Unfortunately I don't have an ESR Meter.

Thanks for the help.

[radiotvnut]

I wouldn't be concerned about the big filter cap; but, I'd change the other two.

[jeyurkon]

Is that resistor to the left of the flyback and to the right of another transformer burned or is it just a shadow?

John

[Eric H]

John, I think possibly it's dirt, I didn't see any burned parts on it when it was out.

I'll replace those two smaller caps and see what happens, one problem is it's been working OK the last few times I tried it.

Better sets than this are available at Goodwill for less than $50 so I don't want to get to involved with it.

[kx250rider]

If too much trouble, just order a rebuilt from P.T.S. Those boards can have real headaches of problems.

Charles

[Zenith26kc20]

Yes the green ones.
In the vertical stage you will see what looks like a 1n4007 diode near the IC. A capacitor is connected to one end of it. that cap is open.
These sets had a real CRT problem so I wouldn't put a lot of money into them. When the CRT shorts it will kill the cathode that is in the shorted gun and the overcurrent will kill the regulator IC, the small transistor near it and a few resistors.
Also, look around the big IC on the left about 2/3s of the way from the rear. Thwere are some small capacitors that drool their electrolyte and open. This causes the picture to tear terribly. If I remember, they are 1 mfd.

[Eric H]

Well it's done I hope.

I replaced the three caps shown plus I replace the three caps on the front side of the Vert IC heat sink.

The set was working after that but it worked most of the time before so only time will tell if it's really fixed.

It cost a whopping $5 to replace all those caps. :-)

Thank you everyone for the help!

[holmesuser01]

I dont know about PTS quality anymore.

I had a Zenith module that I sent in to have rebuilt. They contacted me and told me they were going to just replace my module. The one I received had roach eggcases in the IF section, under the shield. This was about 6 years ago.

[Zenith26kc20]

Module Exchange (if they are still around) sent out a few bad ones too. When Zenith was in business I remember a 9-152 module so covered with roach "droppings" it stunk.
Oddly enough it worked but I returned it as the smell was going to make for a very unhappy customer!