Gauntlet blank screen problem

[Danoodleman101]

Hello,

I have a Gauntlet machine and one day the screen went black, but when i adjust the screen dial on the CRT, the screen turns white. With inspections on the boards, I don't see any blown caps, and all the resistors look clean and have continuity. Does anyone have ideas on what IC's it could be and proper ways to diagnose a bad IC with a multi meter?

Thankyou

 

[Darksoft]

First, I think you need to know if the problem is the PCB or the monitor. Try that PCB in another cabinet or a supergun, or your second option is to plug another known-to-work PCB on that cabinet. Once that is clear, post a couple of pictures about the chasis if that's the culprit. We've got a lot of very talented people around.

 

[Danoodleman101]

I don't have a monitor with the same connector, but I have some VGA conversion kits. I tried that out and got no display still. I have attached pictures of both the monitor boards and the Game PCB.

 

[nem]

Your monitor is likely fine.

Does the game play blind?

 

[Danoodleman101]

Not that I can tell, theres no video or audio.

I want to check the IC's but I find multiple ways to test them with a multimeter and I'm finding different results with each one.

 

[Danoodleman101]

The machine does have power, the marquee lights up, coin mechs are functioning, and the red LED on the game PCB lights up when its plugged in

 

[nem]

Start by checking voltages on the game board. Look up the pinout from the manual.

 

[Funhouse1971]

Have you reseated every socketed chip as these Gauntlet boards have the crappy single wipe sockets and the pins in them suffer from age related metal fatigue and end up breaking.

I had a Gauntlet board which was perfectly fine when put away for storage and a year later I plugged it in prior to installing a Gauntlet Multi kit and there were numerous graphical glitches.

Pressing on some of the chips on the board brought back the graphics temporarily so I knew it was a socket connectivity issue.

Knowing the other sockets on the board were likely going to follow suit at some point in the future I decided to bulletproof the board by painstakingly prising all the single wipe sockets off the board which were associated with the Multi kit just leaving the socket pins in place on the board then de-soldered the pins one by one, however when doing so some of the pins were just breaking away from the board leaving a little stub of pin still connected to the board.

Once all the sockets were replaced the board has run rock solid since.

 

[Darksoft]

Good info. Hopefully something similar is the culprit here.

 

[Danoodleman101]

Thankyou.

I was reseating the chips and when I pulled one off, the plastic socket came loose from the pins, but the pins seemed stable. Ill double check all my voltages and update.

 

[Funhouse1971]

I did say the sockets were rubbish, although handy for when you want to replace them .

You may have been lucky not to have completely removed the socket from the pins as I found it nigh on impossible to get them to sit back over the pins properly when completely removed from the board.

If you have access to a probe you may need to see if the CPU is resetting properly, reset line is pin 18.