Swapped Boards, Still Red Screen

Nessy

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I've spent several hours troubleshooting this issue and I've about given up. I could really use some advice here. I bought a used NBA JAM cabinet and was told it had a bad vertical hold. I figured it was a simple cap or pot replacement but it seems to be a bigger issue. I plan on using this for MAME, so I'm already ahead of the curve on hardware.

Looks like its a 25" CRT with a Sharp chassis, as shown here. Very similiar to the K7000. http://www.thegleek.com/bobroberts/monitor78.html

The monitor projects a bright red screen with vertical scan lines. RGB drives on the neck board do nothing. The controls on the flyback seem to work as well as the vertical, horizontal, brightness, contrast etc controls found on the board itself.

Trying to avoid additional troubleshooting, I went out and found a Wei Ya Chassis on ebay. Figured I could at least give it a shot. Now with the new chassis installed, im experiencing the EXACT same issue as the Sharp, only this time, I actually get somewhat of an image from my computer. ( https://imgur.com/V9GC8RW )

Keep in mind, I get a red screen despite if I have it hooked up to my computer or not.

Could it be a bad tube? Is the chassis not getting enough power potentially making it an issue with the PSU or transformer?

I'm really stumped and help would be much appreciated. Thanks!
 
Sounds like a heater to cathode short in the CRT. A good CRT tester will confirm. CRT tester/rejuvenators usually have a "Remove G1 Short" option but rarely can do anything with HK.

There are several tricks to knock a HK short out but all are risky. A work around would be to modify the neck board to isolate the filament.
 
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