Replace neiman 3m25sf with a Wells Gardner 25k7191 snk vs. capcom Jamma

[MTPPC]

I recently picked up a SVC Chaos SNK vs. Capcom machine with a Jamma board in a midway cabinet. It looks like the neiman 3m25sf monitor has replaced whatever was originally in there. This nieman is not firing green. I've verified it is the monitor and not the board or connections. Now I have also aquired an Atari Steel Talons side by side with at least one good of the two Wells Gardner 25K7191 monitors. The second is dead (although the 2nd game station works besides the monitor).

My question is, can I drop the wells into my cabinet and how to wire it? It appears to be the same size as whatever was in there originally. I'm capable of doing minor wiring mods. I can hook up the power and r,b,g,ground, but how do I know what sync connections are coming from the jamma? I have 6 wires (yellow with various color stripes) coming from the jama board to the monitor through a small VGA adapter board. Please spoon-feed me some info or link so I can figure out how to hook up the last two synch wires.  I have basic test equipment and courage.  I don't have any experience working with CRTs.  I have stripped the isolation transformers from the donor machine and will mount one of those in my cabinet to power the wells if it will go. It is my understanding that I just need to use the two power wires from the isolation transformer and ground it like the rest of the machine. Please correct me if I am wrong.

Here is the layout of the wells: http://www.jstookey.com/arcade/WG_25k7191/WG_25k7191_diagram.JPG . I will be splicing into the pigtails I've cut from the donor machine.

I'm really struggling to find good information on the 3m25sf. Any help, tips, pointers or links would be appreciated.

I found this online: http://niemandisplays.com/nvd%203m%20spec%20electrical%20spec%20sheet.pdf

Do I connect just connect pin 14 of the d-sub to the +v synch on the wells? Do I need to worry about the -v sync at all? What about the +h and -h? I'm sorry my question is so rudimentary.

[ed12]

thats a 24.9" tri-sync
your http is
http://niemandisplays.com/
ask  RICK for a schematic
the phone # is on there main page
if u have any problem's
drop me a pm
i will get the schematic for u
or have him post it
as rick dose post here from time to time


ed

[MTPPC]

Thanks for the quick reply. I updated my post while you were replying. I added a link to the schematic. It shows the d-sub pinout, but I'm so stupid with CRTs, I still don't know what to do.

[MTPPC]

My research tells me that the jamma video sync output (terminal P) is negative polarity. So I should just connect this wire to the -V. SYNC and -H SYNC terminals on the 25k7191 monitor. Is this correct?

[ed12]

yup

also c if it has a input for r/g/b/syc on a sub board ?
if so that's where u want to tie in
it should be on the same board as the db in

ed

[Rickn]

Call me the fix is probably easier than replacing the monitor replace the green video output tansistor if it i s shorted (for green it is the one mounted on a heat sink from top to bottom of te neckboard Blue, Green, RED) check the solder joints on the power resistor in front of that transistor.
Here are a few sugestions on the transistor 2SC3788 or NTE 2508 or 2SC 2SC39533 or NTE 2501

Do not hesitate to call

Rick
519-621-1722

[MTPPC]

Thanks for the tips. I replaced the green transistor and re-soldered the power resistor - no change. When I put the red signal from the vga in the green position, I got a red box under the green label on my game's test screen. When I put the green signal from the VGA in the red input, no display under the red label. I verified the cable is good and I know the output is good because it works perfect on another monitor. Maybe the green is out in the tube. I don't have the equipment or experience to test it further, but I'll probably bring it to my monitor repair guy after the first of the year. These monitors are getting really hard to find so I'd just like to keep one or two as a spare.

[MTPPC]

I brought this monitor to my local repair guy and sure enough, the green gun is dead. Any ideas on replacing the tube? I guess I can use it on a test bed if not. I guess that's why the working game was under $200.

[Rickn]

Not to second guess your repair guy, but we have seen virtually no failures on that tube (made by Samsung).