k4903 horizontal size question

jcterzin

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Hey guys. there are alot of pots on this K4903 that I have running in my pacman, but none seem to change the horizontal size. I can mess with the vertical size, but without being able to fix the horizontal the game is too big for the screen. Which pot is suppose to control this, or is there one?
 
Horizontal width is controlled by the Horizontal Width Coil. This is not a pot. It looks like a round cylinder sticking up off of the chassis. You need a hexagonal shaped tool to turn it, and do not use a metal allen wrench because it conducts electricity and will get very hot very quickly.
 
and that horizontal width coil will only adjust it so far....if you get to a point where it wont adjust any further you'll have the change out the horizontal width cap to another value.
 
I think my hwc must have been glued because it would not budge either direction. Needless to say the core broke. Ive got an old monitor chassis with one, can I use that as a replacment or is there some sort of value to these? also, is there a way to adjust it without the core?
 
Wg 4903

I'm no monitor expert but I have spent a good bit of time recently with WG 49XX monitors restoring a Moon Patrol and Robotron. The 4903 chasis has certain capacitors which expand the horizontal width specifcally for games like Moon Patrol - if you look at the schematic, there is a special note section on the 4903 that gives you the different cap values from the 4901. I'm not 100% sure that the width coil is not going to adjust the 4903 down to a size acceptable for a game like pac-man. Hopefully, a few of the more experienced monitor guys will chime in.

Thanks
Greg
 
what do I do if the core is stuck? I cant get it to shift at all even with the plastic tool. Ive tried everything. If I do need to replace the coil, where can I get one?
 
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That link tells you which cap to change for the 4900. If you can't find it, check the manual...
 
That link tells you which cap to change for the 4900. If you can't find it, check the manual...

the link says that the cap is located at C365 for Wells-Gardner K4900 Series. The manual then says that cap is a .33 microfarad 200v pp cap on the board. which direction should I swap the microfarads to to make the screen shrink? up? I'm thinking up. But how far? Also, the manual has a star next to that cap which states that means you should only replace that part with a factory part... could be bad.
 
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Nah. .33uf will be marked on the cap as 334. Replace it with a 534 (.53uF) cap to start. That will make it noticeably smaller. If it goes too small, then find something in between...
 
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