my 19" CRT shuts off after 20 mins but turns back on if I touch screen

BRI71

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my 19" CRT shuts off after 20 mins but turns back on if I touch screen

What could be causing this... my 19" crt will turn off after 20 minutes of gameplay. Most times, if I touch my finger to the screen, it will turn back on.

Brian
 
What could be causing this... my 19" crt will turn off after 20 minutes of gameplay. Most times, if I touch my finger to the screen, it will turn back on.

Brian

Sounds like it could be just a bad solder connection. When you touch the screen, perhaps the slight vibration makes the solder-joint "reconnect" and the thing comes back on. It really depends on what brand monitor you have for anyone to help you fix it.

Dave.
COINOPSHOP
 
It's an old arcade monitor. Sorry, I don't have the make/model until I get home from work.
 
Bad ground to the monitor perhaps? Without a clear path to ground the monitor could be building up a charge then going into HV shutdown. When he touches the monitor he discharges enough of the power to ground allowing the monitor to operate again....

Just a guess due to a similar problem happening to me recently.
 
I think it's more than likely a bad solder joint somewhere. The face of the glass tube is completely not conductive, you won't discharge anything by touching it. And a bad DAG ground usally causes arcing, not a blank screen.

I'm going to take a stab and say that this is a K4600, which is little more than a picture tube attached to a bunch of cold solder joints anyway...

When it cuts out, I'm sure you could bang on the side of the cabinet and get the picture back too.

But, again, speculation. The type of monitor would help greatly.

"I have an older car. It's blue. It stalls after a while. Why?" :D

-Ian
 
looks like a K7000 variant. could also potentially be the heater circuit, what's that, R201 on the neckboard? I had a K7000 do the same exact thing where the tube would fade out (obviously due to lack of heater function) and you'd tap the cab and it would come back.

after thoroughly reflowing just about every major component on the neckboard it was fine... until of course the flyback went kaboom on it, then I had an assortment of other fixes to apply to it.

the K7000s are prone to cold solder everywhere too though. is the tube shutting down or is it just a black screen? if it hasn't been capped, it's due. if it has a white knob flyback, replace it. if the solder joints have not been gone over on the power header, signal header or any other major spot, it's due.

I worked on a K7200 in a Pac-Man that "wouldn't turn on" and it wound up being a loose AC pin in the power connectors. could be anything, you see.
 
check the neck board for hair line cracks....then the chassis
 
Thanks very much for this thread. My K7xxx 13" also was having a strange "go soft focus and then fade to black" issue. Opening the back of the cab, poking around, then turning back on caused it to work again... then randomly it would start going out of focus and slowly (10 seconds) get dim and turn off, yet there was still HV and I could hear the 15.75 KHz refresh.

I didn't see any bad joints, but did notice a few following back from pin 4 (of 8 pin) which is the heater that had been resoldered before in a couple spots along the way. I reflowed everything from Pin 4 (and pin 5 -- ground) all the way back to the flyback through the neckboard, the jumper wire, the 5 wire bundle down to the mainboard, etc...

Put back together and could not make it fail, even after pressing the neckboard, chassis or messing with the bundle of cords from the neckboard. Seems to be fixed now.
 
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