I finally decided to start working on my 84 Hitachi console to see if I could get something out of the old girl. The set had a dim picture, so I decided to test it with my B&K 470. Sure enough, the red gun was low (still in the good area, but lower than the green and the blue), so I decided to go ahead and "clean and balance " it. The result was not satisfactory so I decided to go for a full rejuvnation, and that worked quite well.

After that I went to ajust the grayscale/focus/convegence. The brightness was still low so I went to the flyback to adjust the "screen" and "focus" control, and as soon as I touched those two pots the neck of the tube started to arc like crazy, and of course that caused the picture to get funky or to not display at all. At that point I decided not to meddle with it anymore. So I unpluged the set.

So, I wanted to ask, what might cause this? Could bad flyback pots cause arcing in the neck of the tube? Could this damage the tube? Before repluging the set for convergence I did check for short with the tester and there was none...

Thanks!

When a tube is rejuvenated, it is common for the rejuvenation process to cause particles of junk to fly around inside the CRT neck and these particles will often come between the gun elements; which, will cause arcing. When this happens, I turn off the set and then turn it back on again. Usually, after 15-30 minutes, this problem will corrent itself and the tube will be fine.

I see, what I find odd is that the arcing was intermitent, so I was sure I did something wrong, that coupled to the fact that it worked fine for 5 mins before I started to play with the flyback adjustments.

I'll plug it again and let it "cook" for 10 - 15 min to see if it goes away.

thanks!

It may not apply hear & may have some risk but.....
About E or F line Zeniths we had 2 that wouldnt focus.
Somehow the HV was bleeding back to the focus grid.
Zeniths instructions were to pull the CRT socket, ground
the CRT focus pin & fire up the set. A little snapping &
it fixed both sets.

That being said RTVnut is correct, arcing is common
after a rejuve, sometimes even H-K shorts usually repairable.
In shop rejuves we would leave on over nite & the next day.
Then turn off for the night for final check & set up.

73 Zeno:smoke: