WGM2574 Monitor Help, BLUE SCREEN

[rb587]

Hello all, I'm new here and new to working on arcade monitors.

I have a working Tekken 2 and centipede cabinet that Ive done basic repairs on, Installed new Power supply, new buttons so I know my way around a bit. The Centipede has some burn in but they both work fine so I never had to do anything with them. I also know how to stay safe and discharge a monitor, I also have electrical hazard boots and lineman gloves from my day job.

Anyway I got a good deal on a "arcade legends ultracade" cabinet the other day and when I power it on I just get a blue screen. The guy I got it from said the computer inside is dead but the monitor works fine. The cab was in really nice shape and the screen looked perfect, powered off at least lol. I threw in a extra 8 in 1 board to test it out and the screen starts flickering/moving but still blue. I do hear the game sound so I know the 8 in 1 works. I dont see any glow in the back of the monitor and I do hear a slight buzzing sound. The only things Ive tried so far is to make sure the neck board is in all the way and unplug and plug back in the RGB connectors.

Any help on where to start will be greatly appreciated.

Here are a few pics

Nothing hooked up


8 in 1 plugged in

[lilshawn]

blue bias potentiometer maxed out (maladjusted) , or broken... shorted blue neckboard transistor.... or tube gun issue.

if adjusting the far right potentiometer adjustment does not change image, suspect transistor.

swap Q503 (blue) with Q504 (green). if screen is now all green, replace transistor. use caution, these traces will lift and break if you look at them wrong.

if swapping transistors does not change image, suspect a shorted blue gun. you will need to locate someone with a CRT tube rejuvenator to blast the blue gun clear of the short.

shorts can happen if the machine or monitor is transported with the tube facing up (on its back.) debris that may be in the tube can work loose and funnel itself down to the neck area and lodge in the color gun.