k7000 horizontal line

nmod

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After replacing the flyback, voltage regulator, HOT, a resistor, and a few diodes, I finally got my screen to light up. But its only in a horizontal line. I can see the game playing within the 1 pixel line. So does anyone have any idea whats wrong with it? Check out the photo. Its on a Bubble Bobble installed in a Super PacMan machine. I just bought it and have been trying to get it to work. Its a WG K7000 board
 

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check to see if your V-size pot is not broke they often are.

check for cold solder joints and broke traces.

check D13 see if it is shorted/bad.

it could be that IC3 is bad.

also update your general location and someone local may stop in and help.

Peace
Buffett
 
buffett left out some magical words. What you're seeing is total "vertical collapse". Basically, your vertical deflection circuit has stopped working completely.

Just thought you'd like some terms to stick in the search box.
 
I suggest turning the brightness right down while you are attempting to fix it. That bright line will burn into the screen real quick.

BINGO!

Yep - check IC3, recap it if it needs it, check the green and yellow wires to the yoke connector (I've seen a wire break off), etc...
 
To add......check the yoke header. I've seen the solder crack open from the (years) of pressure from plugging/unplugging.

Edward
 
To add......check the yoke header. I've seen the solder crack open from the (years) of pressure from plugging/unplugging.

Definitely check the yoke connector. A cracked solder joint there is a very common failure. It's also a common failure in television sets. I don't know how many TV's I fixed over the years that just had a bad solder joint in the yoke connector.

The funny thing is that the joints don't go bad from the pressures of plugging/unplugging - especially since most monitors and especially TV's were never taken apart, not even once. Of course, if it was dismantled a lot, that would also cause the problem... They go bad from heating/cooling cycles, etc. Not only that, but I'm pretty sure a lot of those solder joints weren't all that great when the thing was new.

-Ian
 
Okay so I'm back to this project. I just replaced IC3 and nothing has improved. V-size pot looks physically good. I didn't check it with a multimeter though. I don't see any bad solder joints. I check the yoke connections and they look good. The caps look like they have been replaced recently. I didn't do it. What should my next step be?
 
physically check the pot wiggle it back and forth to see if it is cracked.

check D13 to see if its bad.

check for broken or cold solder joints/traces in the IC3 area and around the yoke connector.

Peace
Buffett
 
check D13 to see if its bad.

The pot doesn't look cracked in any way. Is D13 the one behind the flyback? Its hard to even see it back there. How do I possibly replace that? I don't have a functioning multimeter right now so I can't test it right now, but I have a 3 amp epoxy recitifier diode from radio shack. Can I just swap that in to test it or is that the wrong type of diode? I would like to be able to get it from radio shack
 
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The pot doesn't look cracked in any way.

did you physically move it with your finger wile looking at it. or did you just look at it.

i had one that was bad but did not look like it till i moved it.
that chassis drove me nuts for 3 days till i moved the pot with my fingers.


Is D13 the one behind the flyback? Its hard to even see it back there. How do I possibly replace that?

look in the manual it is labeled on the chassis layout pic. but yes it is there behind the flyback. measure it from the bottom of the chassis.

desolder it if it is bad and place the new one on the solder side of the chassis.


I don't have a functioning multimeter right now so I can't test it right now,

get one you cant do efficient chassis repair without one.
get a DMM.


but I have a 3 amp epoxy recitifier diode from radio shack. Can I just swap that in to test it or is that the wrong type of diode? I would like to be able to get it from radio shack

NO they are not the same at all.


Peace
Buffett
 
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