Zenith 5311U / 24MC32 restoration

[bandersen]

Just as I was about to give up, I found one mixed in with my octal tubes

It certainly draws more current, but no HV at first then it suddenly sprang to life and I got a nice, bright image back. At least until I turned it off and back on. No HV, drawing 200mA and starting to red plate!


I popped it back in the tester and found it has a short. I was able to tap the side a few times and clear it out.
Put it back in the set and it has been been working without trouble for a couple hours.

Even so I'm not crazy about leaving it in the set so took a chance and bought a NOS tube on ebay for $14. I got lucky and it works great!

The image now fills the screen, vertical linearity is pretty good and no more streaking.

I do still need to cleanout the HV cage and fabricate a shield for the HV shunt regulator. Eventually, I'll pull the chassis and go over it too.

Even though it's working pretty well, it's got issues. Like I sporadically loose vertical sync, and focus control is at one extreme, occasional arcing and dirty controls.

[compucat]

Originally Posted by bandersen

Just as I was about to give up, I found one mixed in with my octal tubes

It certainly draws more current, but no HV at first then it suddenly sprang to life and I got a nice, bright image back. At least until I turned it off and back on. No HV, drawing 200mA and starting to red plate!


I popped it back in the tester and found it has a short. I was able to tap the side a few times and clear it out.
Put it back in the set and it has been been working without trouble for a couple hours.

Even so I'm not crazy about leaving it in the set so took a chance and bought a NOS tube on ebay for $14. I got lucky and it works great!

The image now fills the screen, vertical linearity is pretty good and no more streaking.

I do still need to cleanout the HV cage and fabricate a shield for the HV shunt regulator. Eventually, I'll pull the chassis and go over it too.

Even though it's working pretty well, it's got issues. Like I sporadically loose vertical sync, and focus control is at one extreme, occasional arcing and dirty controls.

I occasionally lose vertical sync for a couple seconds. Also, the vertical looks like it is about to collapse then clears up. I have never replaced the vertical integrators so maybe that is the problem. The focus control on mine is at the end of its range even after replacing the string of focus resistors. I wonder if this was the case when new. I restored mine ten years ago and I am quite sure I need some new tubes here and there judging by the overall performance is not as perfect as it was before. I need to look on Ebay for spare parts. I would like to have a new convergence cloverleaf as I had to glue mine back together when I first got the set.