Monitor shutting off 5 sec. after power on - WG25k7191

[snk]

Hello guys.

I just bought an arcade cabinet and I'm in the process of converting it to a MAME cabinet. I'm documenting it and I'm almost done and I will write a documentation about it to share but the last problem I have is with my monitor.

It is a Wells Gardner 25" K7191. When I turn on the cabinet the screen turn on for like 3 to 5 seconds and then I listen at a "Tssss" and the screens turns off while the cabinet is still on. I would like to point out the more time I leave the monitor off, the longer time the monitor will stay on until eventually turn off, but no longer than 5 seconds anyway.

Browsing thru this forum, I did the following: I checked the voltage before the isolation transformer. It is approx 120V. But after the isolation transformer, it is 133V.

Anyway, I tought my isolation transformer was deffective so I bought a brand new one and I replaced it. With the new one in place it is the exact same thing: 133V after the new isolation transformer.

My questions are:

- Is the screen shutting off because 133V is too much?
- If yes how can I adjust the voltage at the output of the isolation transformer ?
- If not, what do you think is wrong ? Should I buy a new flyback, a new capkit, a new chassis or even a new monitor ?

Thanks, regards

[Ken Layton]

If this monitor has not had a capkit then that's the first thing to do. Some dried out caps will affect the safety shutdown (a.k.a. "x-ray protect") circuit. Also this chassis is well known for many numerous bad solder joints all over the main monitor board. Pay particular attention to the solder at resistors R89 and R101. The copper foil solder pads at those locations were tarnished at the factory and solder stuck poorly/made bad contact after a while. Also resolder the horizontal output transistor and flyback transformer connections as well as the video input/sync connector header pins.

[SirPeale]

...

Then after that, check your B+ voltage and adjust if necessary.