Centipede Wells Garner 19K7901

[super56k]

Hello again fellas. I've been so busy as of late, but tonight, my original dedicated Centipede died.
I posted here: http://forums.arcade-museum.com/showthread.php?p=1510084#post1510084 but cleverlyj thought I should try asking here.

It's an upright, and all it does is the game powers up, you can hear sound and play but the monitor remains black. I checked all of the fuses and they are all good. My outlet has a steady 122VAC. The AC wires in the cabinet are all black/white, except for the ones going to the monitor and marquee, they are brown/white. The black/white wires come from the line voltage, but the brown/white are somehow tied in the isolation transformer, rectifier and a huge capacitor. See here: http://www.arcade-museum.com/manuals.../Centipede.pdf page 40.

The monitor is a Wells Garner 19K7901. The voltage going to the monitor measures 128vAC but the neck will not glow. I can't get to the fuse without removing the monitor PCB, but I am afraid of doing that as I don't have a tool for measuring the anode voltage. Any thoughts?

 

[modessitt]

Well, if the fuse is okay, then it's most likely bad traces/pads/solder due to heat behind the flyback. Happens all the time.

Could be more serious like a blown HOT/VR/Flyback, or possible something minor like a popped cap (needing a cap kit installed)...

 

[super56k]

Thank you for the quick reply. Do you believe that the 128vAC going to the monitor is too high? i.e. Do I have to worry about the game board getting damaged?

 

[THE COUNT]

Your 128v will be fine.

You should be able to see the fuse with a flashlight and maybe a small mirror, unless the monitor position in Centipede really is jamming up your view. I know some of my horizontally mounted WG chassis' allow you to see/pull the chassis fuse from just by opening the control panel.

And like Mod said, if your fuse is good you will need to start looking into what is causing the issue further. I'd start by testing the B+ on the chassis. That will start you off in the right direction.

And to remove the chassis you just need to learn how to discharge the anode cup of the flyback. Very easy to do with a flathead screwdriver and a jumper wire. Search here or Youtube it.

 

[super56k]

Ok, so tomorrow, I am going to try and check the fuse and or see if there are any obvious exploded caps or broken traces near the fylback transformer. The weird part was the game was working 100% with a super clear picture then I turned it off, installed locks and turned it back on again and this happened.

 

[modessitt]

The fuse is mounted along the back edge behind the flyback near the tube. Sometimes I find I can just stick my hand back there (power off) under the frame and my fingers will fit between the chassis and tube for me to pop the fuse out. I can test it, then replace it if it's okay. Then I know it's most likely bad solder or a popped cap.

If it's blown, then there is no reason to put another in, as it will most likely blow again. Then you check the VR (IC4) and the HOT, then check C38, C36, D18, and the flyback, along with the caps...