SOLVED: Dead K4900: Turned into a game issue

PassivePac-Man

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The WG K4900 in my Galaga died a while ago. It blew the fuse F501. I replaced the fuse, the HOT, and installed a cap kit, and put it back into the game. I swear I heard something burn up, but I could've been imagining it. It is still completely dead. I am at a complete loss, help?
 
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The WG K4900 in my Galaga died a while ago. It blew the fuse F501. I replaced the fuse, the HOT, and installed a cap kit, and put it back into the game. I swear I heard something burn up, but I could've been imagining it. It is still completely dead. I am at a complete loss, help?

diodes in the 500 section and flyback is where i would start and this is assuming there is no issue from your previous work such as cap in wrong or bridged solder joint, etc.
 
and check those jumpers along the backside of the board. And that resistor in the corner behind the flyback. Look for cold solder on them.
 
yup, as suggested check the jumpers.

also re-flow that entire line on the chassis, the 130vdc rail needs it.


if you hit a brick wall, your welcome to send it in.
if you need parts i stock them.

Peace
Buffett
 
Okay, I did all that but still no change. This chassis has new caps, HOT, Flyback, and I replaced the fuse, which still tests good. I get no neck glow. Help?
 
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Okay, I did all that but still no change. This chassis has new caps, HOT, Flyback, and I replaced the fuse, which still tests good. I get no neck glow. Help?

did you measure the B+?? did you remember on new flybacks you have to turn the screen control pot on?
 
Okay guys. I didn't check the voltage going into the monitor before, and now I find that it's only getting about 9VAC. I guess this isn't a monitor problem anymore. I'm getting 123VAC out of the transformer and 9V at the plug. What could go wrong in between those that would cause this? Thanks

Edit: It also blows the 2A fuse directly under the monitor isolation transformer whenever powered on
 
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Awesome, glad to know what the issue turned out to be.:confused:

thanks for the update.:(


Peace
Buffett

I was not checking the fuses in between repairs, and didn't realize that the 2A fuse was blown, so of course the monitor wouldn't work in between repairs. I replaced the HOT, Flyback, and installed a cap kit. Once I replaced the fuse, it worked, but I have no way of knowing which one was blowing the fuse.
 
shorted HOT can do it. blown flyback may or may not, I've seen bad ones just try to fire indefinitely.

'kitchen sink' repairs can turn out to be pretty troublesome if you replace a mass of parts all at once, and also if they're parts you don't need to replace. if you got your stuff from security vs. say, Bob Roberts, I wouldn't worry so much about changing parts out with bad ones out of the box.

I've at times overlooked blown fuses too. I had a monitor that "didn't work" and it wound up not having a fuse in it at all. and if I recall, there was nothing wrong with it to prevent it from running.
 
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