Monitor Flickers/Loses Power When Cabinet Hit

OU Flight

Well-known member
Joined
Oct 2, 2010
Messages
1,672
Reaction score
32
Location
Spring, Texas
I have a Mortal Kombat 3 that has a monitor that is losing power or flickering when the cabinet or controls are hit or pressed hard. I have isolated it to the chassis by suspending it from touching anything and then hitting the cabinet. It only flickers when the chassis is hit.

I have tried to reflow the solder on the back of the chassis board with no luck. does anyone have any suggestions on what part of the board to focus on? Could this be a flyback going bad or another component? Are there any solder joints on the component side of the board that I may be missing?

Thanks
 
Quit hitting the cabinet.





Solder obviously, but also check that the pins for the power connector aren't hogged out. Check solder on flyback, neckboard, everything big...
 
I'd bet your issue is on the neck board....check your tube connections solder pads.
 
Yes, not hitting it is pretty good advice. :)
Well, after reflowing the board twice, the second time also reflowing the enitire neck board as well, it now works. Not sure what was the problem, but I thinking it must have been the neck board.

Thanks for the help guys.
 
if it's a K7000, then there's a great possibility that was the cause.

they're all reaching that point where cold solder's becoming more of an issue than anything. I had to reflow the entire neck socket and a bigger resistor (the one that controls the heat circuit) and also had to face a cracked neckboard to boot. :p
 
Old, old thread bump...but I am seeing this when I play my Gyruss machine and hit the buttons rapidly. Smacking the cabinet will cause the issue too. I had my wife watch the screen while I wiggled the RGB cable to the board, yoke wires, neck board, PCB harness, power supply, etc, but none of that would replicate it. Is this a common occurrence on a k4900 monitor as well? I recapped the monitor 4-5 years ago, it was my first recap, and I doubt I did any other reflow because I didn't know better.
 
Old, old thread bump...but I am seeing this when I play my Gyruss machine and hit the buttons rapidly. Smacking the cabinet will cause the issue too. I had my wife watch the screen while I wiggled the RGB cable to the board, yoke wires, neck board, PCB harness, power supply, etc, but none of that would replicate it. Is this a common occurrence on a k4900 monitor as well? I recapped the monitor 4-5 years ago, it was my first recap, and I doubt I did any other reflow because I didn't know better.
I would bet money on a cold solder joint somewhere else on the chassis. The K4900 is notorious for having cold solder joints everywhere. But especially check on the 130v rail in the back.
 
Last edited:
I would bet money on a cold solder joint somewhere else on the chassis. The K4900 is notorious for having cold solder joints everywhere. But especially check on the 130v rail in the back.


That's the exact spot I found a cold joint! Not only there, but one of the cement resistors in that section was loose/burned through. I reflowed every large resistor, every header, the neckboard socket, flyback, all ceramic resistors and now there is no more glitching. Thanks!
 
Back
Top Bottom