Two 'working' monitors... but fearful of screwing up. Help?

[Games001]

Hi all,

I have two recent arcade purchases, a working Tetris PCB and Monitor (25" it seems) in a converted cab that was a MK2 long ago (or something Midway that looks damn close to MK2).

The other is a semi'working MK3 PCB and Monitor (also 25" from the measurement) in a converted MK2 cab. (also, a rough guess from shape and CP modification)

The issue is this:

I have attached here pics of the Monitor Tube Stickers, as well as the stickers found just to the left side of the montior CBs, best clairity I could get at the hard to reach entry points, sorry.

The Tetris seems to run just fine, while the MK3 is 'red' and the PCB is ify on joystick and button pushes.  If I were to salvage the cabinets and the monitors, giving the Tetris and MK3 up for restoration of someone else's cabs, how whould I wire these monitors to test the MK3 for this 'red effect' and how would an ArcadeVGA wire up to the tubes?

I know the FAQ goes into this already, but I want to be 100% sure I am doing things right before I blow up 2 working arcade monitors out of my own ignorance.

Pics attached.  Any input on what the 'red effect' in MK3 might be caused by, how to wire these mointors to the ArcadeVGA, or any other 'beginners' steps you think are useful in MAMEing a working arcade moritor would be greatly appreciated.

Thanks folks.

[SirPeale]

You've got two 25K7000 monitors.  The chassis are swappable.

Red can be caused by a lot of things.  Everything from shorted tube to shorted red driver transistor.  I'd try that one first.  Swap the neckboard color drive transistors.

[Games001]

TY Peale, appreciate the insight on the read issue and the 'swap' possible tubes.

I guess my education in serious CRT electronics begins today.

Where does one find the Red Drive Trans. and how does one swap it out?

[StephenH]

In regards to the "Red Effect", I would test this by doing the following:

1) Swap the red wire with either the green or blue wire.  If the color changes on the monitor, you have a gameboard problem or wiring problem.   If the monitor does not change, try turning it on without a gameboard connected.  If the picture is still all red, there is a problem with the red circuit turned on.   If it goes black without the gameboard connected, you have a problem in both the green and blue circuits in the monitor, or possibly the guns of the picture tube are bad.

[Games001]

I pulled the Red Wire off the connector, and this is the result.. I assume from what I am seeing, the board is having issues (as expected) since the Blue/Green colors still seem in full effect.

Opinions welcome to confirm or deny these findings.

[SirPeale]

I'm 99% certain it's either a tube fault or a shorted color neckboard transistor.  Good if it's a transistor...sucks if it's the tube. 

[SirPeale]

If you want to test the neckboard theory, just swap chassis'.

[StephenH]

Yes, it would seem that it is likely a gameboard problem.   However, if you connect the Blue or Green wire to the red input on your monitor, this will tell for sure.  If the picture is readable and what would normally appear green or blue appears red and readable), then it is a gameboard problem.   If the red color fills the entire screen like your first picture, there is a problem in the monitor. 

[Games001]

It's the monitor, sad to say.