Image too big on K4900?

[OldTymeToys]

Hey guys- I put a 60-in-1 in my JAMMA cab with a K4900 (4953) today. No matter what adjustments I make, the image is stretched top to bottom and you can only see half of the "iCade" text at the top on the game select screen. When playing- some games you can only see the bottom edge of the high score and others, like Galaga, you can only see the top edge of the stages and extra men.

I'm assuming this adjustment should be the horizontal centering pot, but which ever way I turn it, it doesn't completely fix it. I think the entire image is actually too big on the screen and needs to be shrunk somehow...

Does this make sense??? What else can I try? Any help would be much appreciated!

 

[Dokert]

adjust the HWC (Horizontal width coil)

 

[modessitt]

Or change the value of the horizontal width cap...

 

[OldTymeToys]

adjust the HWC (Horizontal width coil)

Duh! Thanks man! I don't know how I missed that. Even after looking through the manual!!!

 

[Dokert]

Duh! Thanks man! I don't know how I missed that. Even after looking through the manual!!!

Kiss principle Brother

 

[OldTymeToys]

Well, I wish it was that easy! I tried adjusting the horiz. width today and it would never stabilize. I'm guessing I need a new one? Is the the correct one for my 4900? http://www.therealbobroberts.net/wc4.jpg

 

[KenLayton]

Or change the value of the horizontal width cap...

Capacitor C365 sets the width range. The factory installed value is .33 uf @ 200 volts polypropylene type. Changing the value will change the horizontal size of the picture. Generally the next value up or down is all it takes.

 

[OldTymeToys]

Capacitor C365 sets the width range. The factory installed value is .33 uf @ 200 volts polypropylene type. Changing the value will change the horizontal size of the picture. Generally the next value up or down is all it takes.

So if I go down in value will the picture be smaller or is it the other way around?

 

[modessitt]

Larger the value, the smaller the picture. If you have a 334 and want to go smaller, try a 534...

 

[OldTymeToys]

Larger the value, the smaller the picture. If you have a 334 and want to go smaller, try a 534...

Thanks Mod- I'm worried the width coil is damaged too. I don't know if you can see from the pic but it looks to be unraveling towards the bottom?

 

[modessitt]

If you have any picture at all, it's good enough. As long as it still goes round and round and is connected to the chassis on each end, then don't worry about it for now...

 

[OldTymeToys]

Good! I'll order higher cap and post how it goes! Thanks!

 

[KenLayton]

The next sizes up and down in value from the .33 uf are .39 uf and .27 uf. They MUST be polypropylene types because they are in a horizontal deflection circuit (they work very hard, ordinary capacitors will fail in short order and take parts out with it).

Your width coil looks normal.

 

[OldTymeToys]

The next sizes up and down in value from the .33 uf are .39 uf and .27 uf.

Your width coil looks normal.

Thanks Ken!

 

[modessitt]

Bob sells a kit of various sizes. Sometimes you have have to use two to get a specific range.

When I do tube swaps, I pull various ones off of the TV chassis' and keep them for this purpose...

 

[OldTymeToys]

I can't seem to find the kit on Bob's page- Mod, do you know where it is on his page?

EDIT: Found the cap: http://www.therealbobroberts.net/cap039v2.jpg but you mentioned a kit?

 

[KenLayton]

http://homearcade.org/BBBB/width.html

That .39 uf one you linked from Bob's site looks correct.

 

[OldTymeToys]

http://homearcade.org/BBBB/width.html

That .39 uf one you linked from Bob's site looks correct.

Thanks again Ken!

 

[PrairieDillo]

I recently got a bunch of caps from a local place that is electronics surplus.
I made my own width cap kit for $1 and can spare what you need.
I can just send you what you may need. Let me know if I can help.

 

[OldTymeToys]

I recently got a bunch of caps from a local place that is electronics surplus.
I made my own width cap kit for $1 and can spare what you need.
I can just send you what you may need. Let me know if I can help.

Damn man- too late! I ordered from Bob yesterday. I needed a few other things as well, so not really a big deal. Thanks for the offer!