newbie question

[sp0rk]

I've already searched the boards for a while.  I know most of the questions here have to do with PC's.

I'm setting up a jamma cabinet.  I have a 'working monitor' that I bought from a guy, but it didn't have the wiring (RGB) on the monitor to hook it up, so I've been trying to make my own.

A couple questions.

1)  I know i have the RGB correct, what about the 'composite synch'?  Is this the +h and +v (horizontal and vetrical) or the -h, -v?

2) the two wires not from the jamma harness, ground and synch.  They are both black on all three cabinets I own.  Do these go in any order?

I'm thinking it's something with the wiring I'm dong wrong, since when I power on, the monitor is obviously on, but doesn't show anything.  It starts to make a really high pitched hum.  When I turn the switch off, you can see the monitor 'shut down' (ie, the screen goes in to the middle in a square as it dissapears).

Thanks for any help!

[SirPeale]

And the make and model of the monitor is.....?

[MonitorGuru]

Jamma boards are all negative composite sync.  Attempt to connect the single sync wire to the -H first and see if you get a picture. If not, try the -V.  If still not (or garbled) then split the wire in two and send it to both -H and -V (do it by sticking a spare wire in the end of the jamma harness and splitting it, dont cut the wire until you're sure that is what will fix it)

Depending on your monitor, you may need to run the ground next to the RGB inputs (usually 4th one in after RGB) and also to the sync block (usually before -H and -V)

[sp0rk]

thanks. 

I tried again and still no luck yet.  I'm wondering if the monitor may have gone bad, although it was sold to me 'tested' and 'working', but I didn't see him power it up.

One other thing, The monitor has a different chass on it, so it isn't grounded into the metal of the cab.  Any chance this could have anything to do with it?

Thanks for the help.  I noticed my other monitors are all wired with negative v and h (with the wires split).

BTW it's a wells 49.

[MonitorGuru]

Turn up your screen control on the flyback transformer (big black thing with the red wire comming out of it going to the tube). It may have been bumped low and not giving enough brightness to the screen.


Do you hear the high pitched whine change when you connect and disconnect the sync wires? If so, then the monitor is working with deflection correctly.

The monitor frame should be grounded to the ground strap off the power board/cord comming into the game/off the metal frame of the isolation transformer in the bottom of the cabinet.

However it doesn't "need" to be grounded to that to work, it's a safety issue instead.


By different chassis do you mean it was a Wells K4900 and now replaced with a replacement chassis on a black plastic frame instead?

[sp0rk]

Ok.  I turned my brightness up.  That helped, because I noticed a vertical blue line got brighter, and I could see it change.  So, I messed with the horizontal settings.  I got a beautiful picture, but it was bright.  I went to turn the brightness down, and now all I get is the blue line again.  I'm guessing I'll need a cap kit, because for a brief instant the screen had some horizontal bars in it, then they went away into a crisp picture, and now no matter how much I adjust the horiz/vert, all I get is the vertical blue line. 

Cap kit?

thanks for your help.

[MonitorGuru]

You may need to also adjust the drive (on chassis or neckboard) and cutoff controls on the neckboard for each gun to see all the colors.

As far as getting a single vertical line, that means (assuming you're looking at the monitor like a TV--wider than tall) that your horizontal deflection is not working. 

That could be caused by the yoke wires not connected to the chassis in the plug or the wires from the cable starting to come off the yoke itself.  Or you could have a bad width coil or adjustment dial, or as you said bad capacitors, though if you had it for a moment and now it's gone, its more lilkely to be the adjustments or the yoke wires as a capacitor generally will fail slowly collapsing the image not an all one minute, nothing the next (though it could happen)

[sp0rk]

Thanks for all your help.

I'll try some other things later.

One more thing:

I have a buster bros game that I just replaced the monitor in.  The new monitor is awesome, has great color, but it's too wide, the sides are off the screen.

I see no horiz adjustment, I'm assuming it's this coil.  How do you adjust that?  Does it turn somehow? I haven't touched it yet because it's not an 'adjustable' knob like the other ones, and I don't want to mess up a perfectly good looking picture.

Thanks again.

[MonitorGuru]

The horizontal width coil is unlike normal "knob" (potentiometer/variable resistor) controls as instead of a level of resistance, you are turning a fragile piece of iron inside a coil to affect the image.

You need a special set of hexagon nylon / plastic adjustment tools. BobRoberts sells them, as do RadioShack if they still have hobbiest parts in your local store (some no longer carry them)

A full set of 4 cost about $4.   Do NOT turn it with anything metal like an allen wrench (it affects the image while you place it in the coil so when you remove it it will be wrong, AND it can get hot, AND it can break the fragile iron core.  You need to turn it with the unit on otherwise you will constantly be adjusting, powering back up,etc...

On newer monitors like the JennShinn and WeiYa replacement chassis, they usually mount a nylon adjuster in the coil so you can just use that, unless it fell out/is lost.


Since you have another, game I'd try taking this monitor you're working on over to it (slide both games side to side or 45 degree angle back to back (just enough to get in) and then connect the buster bros video output into the one you're working on and vise-versa.  That way you can determine if you're wiring and boards are okay in both machine before you start digging deeper into this particular monitor with the blue screen.

[sp0rk]

thanks for all your help.  It's greatly appreciated.

:>