Blue Hue/Tint after warmup / WG19k4906

delf

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Hi all,

I hope someone can help me track down or troubleshoot this problem I'm having with my Wells Gardner 19k4906, which is located in my Ms. Pac-Man machine.

I've had this machine for about a year, and when I received it, it had some monitor issues. Specifically, it would randomly flash a bright white on the screen for a mere second, and then go away. It wouldn't happen very often, but maybe once or twice during a game. One day, after power on, and a 15 second warmup cycle, the screen displayed what you see in the photo. Powered off, back on, same thing. Then it quit, and was normal.

So, I decided it was time for a cap kit. So, I ordered one from Bob Roberts, and pulled the chassis, and installed the cap kit. Everything worked just fine, but, the problem persisted. Today, the monitor seems to be stuck in the mode in the picture, of what you see after a 15 second warmup. The monitor looks great prior to then.

I've checked the caps--they are all in the right orientation. Being that this problem occurs when the monitor warms up after about 15 seconds, makes me think it's a component of some sort causing the issue. Anyone have any idea?

I've attached photos to this posting--sorry, I was having a heck of a time getting the monitor to be photogenic. It's hard to see, but the background is blue-ish in nature.

I've swapped boards, so I can rule out the board being the problem. I'm certain the problem is in the monitor itself. I've also checked the connections, wiggled wires, etc, and I just dont' see anything physically wrong.
 

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I would turn down the blues then see how it looks, if still blue pull the drive transistor for blue out of the neck board, if still blue you have a short in the tube and need to zap the tube.
 
Hi All,

Sorry, it has taken me some time to reply back to this post. I had to pull the machine back out and get into a good frame of mind.

So, I resoldered the connections on the neck board (Good suggestion), and removed the Blue driver transistor on the neckboard (this is right, isn't it?), and I"m still receiving the blue screen :( As an additional, troubleshooting step, I moved the transistors around and removed some of the others one by one, just to rule out the possibility that it was another transistor on board.

What I don't understand is why it does it when it warms up-- The first 10-15 seconds of a power on, the color and picture on the tube looks beautiful. After the 10-15 seconds, that's when you see a screen full of blue. Can someone explain that to me?

I appreciate everyone's effort.
 
well since you had the transistor out and swapped them around and still having your blue blasting I would say its your tube shorting the blue gun. find someone who can rejuvinate it for ya. as far as why it happens 10 seconds after you turn it on, its 30 years olds and tired. I have a k4600 that flickers green for a few seconds until it warms up, just how they are now, I zapped mine quite a few times and only get a quick flicker now then.
 
Well, geez, i don't know..

As soon as I posted my response earlier, I was standing back looking at the blue screen, and decided to fasten the control panel latches, and voila! The problem cleared up!

I've been banging around on the blasted thing trying to get it to go back to a blue screen, and I can't do it! So, maybe I have a loose connection somewhere on the chassis board, and I'm just not seeing it? Or do I have a tempermental tube?

I should have touched up the chassis board when I did the cap kit. At a minimum, inspect it a little more closely.

The mysteries of the universe...
 
Could have had some debris inside the cathode shorting out the blue gun that shook loose when you latched the control panel. It's a possibility if you couldn't find anything loose on the chassis.
 
if it's not the transistor on the neck board and all the other parts are good on there.
Did you test the tube with another chassis or rejuvinator?
if the tubes for sure good and the neck is then you need to look down at the RGB card it's the lighter card with less parts on it.

chances are you have one of the transitors in the blue drive out. follow the blue wire input down to the correct one and test those. there's one side that'll make the chassis blue and the other side will cause it to be missing.

one way to tell without a meter is just to swap them and see if you now have a different color. hope that helps.
 
I actually came across a TV that had the same symptom except for it was red. There was a resistor that was open on the neck board for that color. Test all resistors that is in line with the blue transistor. Worth a try. If nothing then I would also suggest hooking it up to a tube tester.
 
then you need to look down at the RGB card it's the lighter card with less parts on it.

that is a 4600 chassis.

he has a 4900.

i would get the tube checked if the problem returns.

it sounds like the crud was knocked off the gun like others have said.

Peace
Buffett
 
Ugh oops sorry about that.
yeah the 4600 has the daughter cards the 4900 has all the color drive transistors near the top left of the chassis.

But first off test another chassis or tube and see what you get. If you put another chassis on the tube and it's blue then it's your tube's cathode guns. You'll need a rejuvenator at that point to clear the short.




that is a 4600 chassis.

he has a 4900.

i would get the tube checked if the problem returns.

it sounds like the crud was knocked off the gun like others have said.

Peace
Buffett
 
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