View Full Version : Zenith M2737U (14M23 Chassis) Horizontal Issues.


OS X
08-19-2016, 03:56 PM
Now the other Zenith is 95% finished and working, I've decided to start back on this one again. The issue I'm having with this one is the horizontal starts to shrink after running for around half an hour, all the electrolytic's have been replaced and the paper and black beauty caps have been as well it's pretty much fully recaped, works great with the typical sharp Zenith picture for around a half an hour although I did notice there is a waveeness to the picture, I've also lost vertical once but have not had any problems ever sense with that, whatever component it is that is causing this does not like heat, as I put a small PC fan underneath the chassis and it ran fine for 2 hours but obviously that's not a permanent fix though :) I also noticed the power transformer seems to be running very hot to the point where you can't really touch it very long if at all. I tried freeze spray on the resistors and pretty much everything underneath the chassis as I can run this set upside down being the CRT is attached to the chassis and nothing changed, I've also tested resistors and changed tubes even though they tested good and that didn't seem to do anything neither. The set originally had a shorted electrolytic that I replaced and it brought this set back to life and I ended up replacing all the electrolytic's. I really don't know where to go from here my troubleshooting skills are limited, and the only real piece of test equipment I have is my multi meter and variac if you guys have any ideas about this issue let me know. Thanks again :)

Electronic M
08-19-2016, 07:51 PM
If the schematic lists voltages check all B+ rails and all listed horizontal voltages before and after shrinkage.

OS X
08-21-2016, 02:24 PM
If the schematic lists voltages check all B+ rails and all listed horizontal voltages before and after shrinkage.

Checked all the voltages that I could and all checked within spec of the schematic even when the horizontal issue is happening, so I took it to one of my firends that is a expert with restoring/repairing vintage TV's. I replaced even more resistors and even changed out the orange caps that usually stay good but no change whatsoever, from what we found out it's either going to be the yoke or the flyback more than likely, one thing I failed to check was the flyback after running around 30mins we checked it and it got so hot it would actually burn your finger and you couldn't touch it, even with the flyback cage open it still gets hot which in turn seems to make the power transformer extra hot, I put a fan isolated on the fly back cage and the thing ran fine for hours and the Flyback stayed cool so my guess is the fly back has some kind of a short or something in it as everything else has been checked. I have a replacement fly back so I think that might be my best bet as of now :)

Electronic M
08-21-2016, 04:26 PM
Probably is the fly/yoke then.

One note, with problems like this the voltage measurement is not about tolerance of the schematic (though that should also be confirmed) it is about CHANGES in voltage measurements between when it is working right and when it is not....Where it changes can tell you where you need to dig deeper.