TECH: WG 7901 no glow - repaired 10/24/08! thanks Ken

[Tenn_pin]

Just got this Galaga machine and the monitor does not work.  There is no glow in the CRT but there is 5V going to the small board that plugs in the CRT.  No static from the CRT. Where do I start?  Thanks for any advice.

R

[Ken Layton]

And this is after it has been recapped?

[Tenn_pin]

Sorry for the delay, but I have not recapped the boards.  Is there a way to know if a cap kit will fix the problem before doing the recap?  I also have come across a burned in Ms Pacman monitor without any ID, buy it only has a 6 pin input.  Can the negative H and V lines be put on the positive H and V lines to get it to work?  Without the H and V, there is a rolling fuzzy picture that also happens when I hook my Defender monitor to the Galaga.

Thanks for the help Ken.  I have read several of your posts and you do such a great job providing understandable instruction for us newbies.

[Tenn_pin]

The Ms Pac monitor is a WG 19K4615.

[Ken Layton]

Sorry for the delay, but I have not recapped the boards.  Is there a way to know if a cap kit will fix the problem before doing the recap?  I also have come across a burned in Ms Pacman monitor without any ID, buy it only has a 6 pin input.  Can the negative H and V lines be put on the positive H and V lines to get it to work?  Without the H and V, there is a rolling fuzzy picture that also happens when I hook my Defender monitor to the Galaga.

Thanks for the help Ken.  I have read several of your posts and you do such a great job providing understandable instruction for us newbies.

Bad caps will prevent startup or can cause instant shutdown. A blown fuse, bad horizontal output transistor, bad voltage regulator, bad flyback, bad solder joints, yoke cable unplugged, etc. Any of a hundred things can cause the problems you describe on the 7901 (k7000 series). Nine times out of ten it's because of dried out/off value electrolytic capacitors. You won't know until you pull the chassis out and inspect it (or have someone inspect it and test capacitors for you).

As to the 4600 series, there are ten different video interface cards issued for that series (each with a different "P" number like P302, etc). Here is a list of the video/sync connector pinouts of the various 4600 video interface boards:

http://www.ionpool.net/arcade/tech/19K4600_pinout.txt

Some accept both positive and negative sync (on seperate connector pins of course). Some accept positive sync only, some negative sync only. Feeding the card the wrong sync doesn't work.

[Tenn_pin]

There is no markings on the card I have for the 4615.  It seems the card I have is only a 6 pin at P205 and I will need a card that has the P204 as a negative feed, since that is how the 7000 monitor set up.  Where can I get a P306, which is what the original board was?

I will get the cap kit for the 7000 when Lizard Lick has them in stock again.

Thanks,
Randel

[Tenn_pin]

It turns out that the cap on the neck board was bad.  Thanks Ken for the help.  I did recap the board with a Bob Roberts kit and the monitor works great.  Now it is on to the repair of the ever resetting Defender...