25k7191 trouble shooting

[scotthh]

I picked up a  TMNT cabinet, which came with a 10-year old 25" WG 25K7191 monitor, power supply & isolation transformer. The seller said "it was working before a wire popped loose & grounded some power."

I thought perhaps this had blown a fuse, but the ones near the power supply and the one on the monitor board appear intact.

I tested it with a jamma harness and a board, the monitor is getting power, and shows some color beams when it powers down, but otherwise doesn't display a picture. I would guess that the color beams mean the CRT Filament is lit (as per the troubleshooting chart in the monitor manual)?

The next step according to the manual is to "check along video channel from video input at PI to Video Output Transistors on neck board."

I thought I was following along until this point, but now I have no idea what to look for.

Any help would be appreciated.

[SirPeale]

Using a multimeter, make sure your board is getting power. 

[scotthh]

The board was getting power originally (at least the red lights on it were lit).

Well, after I got it home I connected the jamma board and harness and the monitor a second time. I don't know if it was the ride in the back of a truck, a better wiring job, or the couple of drinks I had with dinner, but the monitor is working.

So there's a new problem, the picture is "smeared", the text is great, just the graphics. My first guess is that the temporary wiring job isn't helping this, but is this symptomatic of some other problem?

Thanks.

[SirPeale]

Some kind of board problem.  First, verify your voltages are correct.

[scotthh]

Thanks Peale,

It was doing 16v off the 12v rail and 6.8v off the 5v. I lowered the adjustable voltage, got it to around 15.15 and 4.95, and now the picture is perfect.

Thanks!

[SirPeale]

15 is too high for the 12V, and 4.9 is too low for the 5V.  You should either rebuild that PS or replace it.