19K7201 screech/green Screen

[Mauzy]

Hey everybody.
In early 2007, I posted a thread here about my WG 19K7201. The first thread (http://forum.arcadecontrols.com/index.php?topic=64580.0) helped me out with the sync (turns out it takes a negative signal) I also mentioned that there was a squeal coming from the chassis. I have been running it in  my Gallag cab for about a month and a half now without any problems. Yesterday I turned it off (crap! there goes my high of 106720...) and tried to turn it back on. Now, the screech is LOUDER than the game itself, and the monitor turns solid green with a few scan lines intermittently. I noticed months ago that if you LIGHTLY tap the neck card, the picture comes back, but this will only work for about a minute before it goes back to green.

The screech seems to be coming from the part that is circled in red. The other pic is the green screen. The grid in the background is from the Gallag startup.

So I guess my question is, how do I address the green screen, and what to do about the screech? replacement part, or new set of chassis?

[grantspain]

check for bad connections on the green drive transistor and change it if neccesary(on the neck card)

[Mauzy]

All connections seem to be fine. After testing, green screen hasn't come up. Not sure what thats about. Now to tackle the screech...

[qrz]

the crt may have an intermitent heater/cathode short . this will cause the symptom pictured.
the short will cause higher than normal beam current in the tube . this will also increase power demands on the power supply. switch mode power supplies regulate by frequecy or pulse width control.
 therefor, the operating frequency may drop into the human audiable range under a high current condition.
note : many smps's will squeal loudly when a secondary short exsists.

btw, there is a way around the hk short (without replacing crt ) . send pm for further instructions if needed.

qrz