Help wg 4600 series monitor video interface board problems

[GMZombie]

ok this is the deal i have one of the 4600 series monitors from WG and i have put in a new Cap kit...now the video interface board that was in it....which had a negitive and positive sync pins on it has died also....i know this cause after i swapped the caps and pot on the video board it will not fire with THAT video interface board....but if i put in my other board,which has just negitive sync pins on it will fire up right away... by the way im trying to get my mame machine back up running and that uses positive sync or composite, anyways when i try to fire up the bad video board all i get is black screen...but i can adjust the pot on the video board and it will get lighter and lighter. I cant think of anything besides changing out all the little resistors and npn transistors to fix it but dont want to if someone knows what i can do?? thanx for the help

[Ken Layton]

The video interface board is the least troublesome board in the 4600 monitors. When this board does give problems here are the causes ranked by most common to least common:

1) Bad black level trimpot (hairline break inside of it)
2) Bad solder joints on the connectors
3) Bad transistors
4) Bad zener diode

What is the "P #" on the paper label (locatedon the parts side of the board) on your video interface board? Example: P305.

[GMZombie]

it dosent have a paper label on the parts side...looks like there was one but it isnt there anymore....this is what i know about this monitor. it is the original monitor out of a pacman machinewhen i got it the guy said that it didnt power up. got it home pulled the monitor and checked and sure enough it didnt power up. i then took the interface cards out of that and put them into my known working 4600 series monitor. i checked one at a time first the video then the vertical/horz. board...the vert/horz board was the culprit. being that ih ad to use a positive sync for my mame machine as i didnt feel like swapping out monitors i used the video interface card from the pacman to get my mame machine workin. it worked for a little bit before the screen when dark except for the top of the screen you could see a bit of color but only a line.....this is where i put the cap kit in thinking that would fix the problem..well i had a picture again but wtih the old video board and not the one from the pacman. i tried everything to get the pacman video baord workin but i couldnt...the monitor went out in a way that the machine looked like it was being filled up with water.....it would be full screen then slowly go up till the top once it got there i couldnt get it back down...i believe the chassis was either a 4602 or 4606 them sound right....the vidoe board is white with a total of 9 pins 6 for the first connector and 3 for the second connector for the positive sync. Also i have a problem with a vertical/ horz board....when i put that in, as it ws from the pacman machine, the video will not start up...do you know anything on this board as well...either from the 4602 or 4606 series monitor...thanx for the info and if you want a pic of the boards i can get them for ya.

[Ken Layton]

Yes, please post pictures of the problem video interface board (parts side and foil side) and just the parts side of your hor/ver board.