Adjusting Sync in a k4900

whoamonga

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Just to make sure I got this right, I wanted to run this by someone...

To adjust the sync on a WG k4900, one would first, jumper TP601 and TP31. (At this point, will I still have an image??)

Then, adjust the horizontal hold control VR351 'til the picture snaps into place.

This sound good?
 
without looking at my manual, that sounds right to me. do you not have an image when the TP's are jumpered?
a bad vr 351 wouldnt keep image on screen right. jumps from not being able to set right. clean it first. if you arent getting image you might have sync wires wrong. i install my sync test connector. i can change the input easy without getting shocked.
 
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I haven't tried jumper-ing this one yet. Will tonight. But every time I've jumpered the resistor on a k4600 to adjust the sync, I lost picture and couldn't see anything to adjust. Had to guess...

So just wondering if I should expect that with this.

The monitor will hold a sync with certain games just fine. Just not with the one I want it to.
 
What's the game you want it to hold sync on, and which way is the sync hooked up?

I never do the jumper thing. I start with a properly-rebuilt chassis, connect the sync wiring in the way the board requires, make sure the B+ is set properly, then adjust the hold pots if necessary...
 
Firstly, thanks for your help!

Monitor's perfect w/ Snow Bros., out of sync w/ Time Killers.

Time Killers has a dip switch setting to switch sync to positive/negative. Neither work, though behind the mess I see the overall color of the screen changing (game working).

How many ways can sync be hooked up? It goes from the JAMMA harness to the connector of the monitor... The black and white wires are where they've always been: on those 3 header pins.

What is B+, and how does one set it?

Thanks again.
 
On a K4900, composite negative sync (as from a JAMMA PCB) should only hook up to the negative horizontal sync (pin 3) only on the 3-pin section.

So - your pins would be wired like this from front to back (when looking at the connector):

1-red
2-green
3-blue
4-ground
5-not used
6-not used
7-no pin
8-not used
9-not used
10-negative composite sync.

Sometimes I've seen these monitors sync with the composite also attached to the negative vertical pin (#9) but not often. When you are using negative sync for the JAMMA on a 4900, it usually won't sync if the vertical pin is connected....
 
Good info here, I'm going to keep my eye on this one as Tim dropped off a 4900 on Saturday that's going into my Time Killers cab as soon as I get all the cab wiring checked out and control panel rebuilt.
 
I think I usually see a black wire and a white wire from the harness to the monitor headers. One going to pin 10, and one spliced onto 8 and 9. Let me see if I can find a picture of it.

At least that's what I normally find on the k4600s....
 
I think the video ground is what I'm talking about...

Here's a pic of a 4600 w/ the black and white wires I'm referring to:
http://i282.photobucket.com/albums/kk259/whoamonga/arcades/chelnov4600002.jpg

How is this relevant to the problem you are having? You started this thread by asking about adjusting sync on a 4900, not a 4600. The two monitors behave differently, and the way I told you to connect the negative composite sync is proper for a 4900, but would NOT be proper for a 4600.


dmbj said:
4 or 8 can be used as video ground. they short to each other.

I know. I just used Pin 4 because most connectors already have it that way....
 
I didn't have a pic of a 4900, so I used one of a 4600. I was trying to illustrate only the black and white wires, regardless of monitor.... so that I might know the purpose of each wire. White = sync? Black = video ground?

But I adjusted the Sync pot and got a clearer picture, but now the image is rolling uncontrollably. Hold pots can't get the image to hold still. Normally they'll snap into position, but at the VERY SLIGHTEST tweak in the other direction, the screen will roll the other way. No minuscule amount of adjustment will hold the picture either vertically, or horizontally. It's just like the square screen moving diagonally over and over...

Weird thing is, it doesn't do it with a different JAMMA board. Threw in an Avengers board and it worked fine... But i think it's ALL weird because this VERY SAME Time Killers board worked in there a few days ago...

So does this seem like a board issue?
 
Board issue... tried it in another cab and same thing...

I'll start another thread about the board to avoid confusion w/ the monitor...
 
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