QNIC CGM 2500 25" MONITOR - power but no image

djpurpose

New member
Joined
Apr 15, 2012
Messages
8
Reaction score
0
Location
Sacramento, California
QNIC CGM 2500 25" MONITOR - power but no image

Just purchased an arcade cabinet with the monitor inside no board (going to use PC with mame). The person I bought the cabinet from swore the monitor worked but couldn't show it because the power supply was out.

I got it home and since I will not be running a board with this I figure I don't need the power supply. I hooked up a power cord from the wall to the isolation transformer thing that powers the monitor and marque. When I plug in the cord I can hear it get power (high pitch hum) and if all the lights are off I can see the tube neck lightly glowing orange. But no glow comes from the monitor, even tried playing with brightness on the extra board with the knobs for contrast and all but still no light comes off the monitor.

I figured that maybe i needed a video signal for it to show anything so I cut up a vga cable carefully and wired up the composite sync, ground and r,g,b to the monitor board. Turning on the computer doesn't give a picture at all.

The monitor does however flash when I connect the power and disconnect the power so I am hopeful. Here is a short youtube video that shows the monitor when power is connected and disconnected.

http://www.youtube.com/watch?v=sRt5VePeqXM

Specs:
Chassis: QNIC CGM 2500 25" monitor
Tube: RCA A63ADT10X05
Input: PC with nvidia 6600GT vga out, broken out to composite sync, RGB and ground.

Thanks in advance for any help you can provide.
 
looks like it is working to me.

turn up the screen nob on the flyback and you should get raster lines and a wite screen.

but from what you describe it's working fine. and it flashes when its turned off that's a good sign.

other than that i know nothing about that chassis type.

Peace
Buffett
 
I just played with what I think is the screen knob and there was no change. There where 2 knobs I adjusted the top one (bottom was epoxied in place so I assume that one was the focus). So even after turning up the screen knob and brightness it stays pitch black as if I had no power to it.

I assume that even with no video source at all the monitor (front screen) would have a little bit of light coming from it if there is power to it. Am I correct? Cause even with the lights off and getting really close to the screen I cannot see even the faintest hint of light coming form it, only the neck has a slight glow, the front shows nothing though.

As a heads up this is my first machine and up until 2 days ago I only knew where to put quarters on arcade machines. I'm a quick learner but I have to admit I'm a little overwhelmed with this one.
 
the bottom knob with the hot glue is your screen nob.
break off the hot glue and turn it up to see.

otherwise your screen is probally adjusted fine and no need to mess with it till you get a signal to it.

and sometimes without a signal it is hard to trouble shoot a monitor. not always but sometimes.

i also know nothing about Mame so i am no help there.

Peace
Buffett
 
Ok I adjusted the screen knob and presto, I get something but it appears to be getting no signal at all from the computer. I took a picture of what I get.
 

Attachments

  • IMG_3162.jpg
    IMG_3162.jpg
    29.3 KB · Views: 18
that's what you should see.

your monitor works.

now its up to some one else that knows about Mame to help you the rest of the way.


Peace
Buffett
 
I suppose that I need to get a signal to it before I can figure out if the picture on the mointor is messed up but after adjusting the vertical size knob that was as large as the picture would go. Now I'm not sure if that's because I have no signal to it or if that means something is going bad and I need replacement parts.
 
all that is doing is adjusting the raster.

i have seen and fixed chassis that this would happen. after a signal was applied the image would adjust off the screen like it was supposed to.

you need a game with a steady RGB signal to test it with to see if there is something wrong with actual image size.

Peace
Buffett
 
So I double checked my vga breakout cable and I can at least confirm that the PC side of the vga breakout cable is correct so the cut jamma cable that was originally hooked up now looks like this:

PC side --------- Jamma connector side
vga pin 1 ------- red wire
vga pin 2 ------- green wire
vga pin 3 ------- blue wire
vga pin 5 ------- black wire
vga pin 13 & 14 ------- gray wire

Now comes the weird part:

Option A (original wiring)
I have attached a picture of exactly how the cable was hooked up to the chassis when I bought it (IMG_3167.JPG):
Red, green, blue, [3 empty], black (ground?), [empty], gray (composite sync?)

Option B (labeled on the board)
If you look though the printing next to the chassis connector it seems it should be:
Red, green, blue, [empty], horizontal sync (wire color?), vertical sync(wire color?),[4 empty] ----- (the labeling on the board doesn't show anything for a ground)

Option C (wiring diagram setup)
Now the last option is the wiring diagram here: http://www.freeinfosociety.com/electronics/schematics/video/pictures/qniccgm2500.jpg which I'm not sure how to read (and it doesn't seem to match the board all the way). It has 9 pins split up rather than 10 pins all together like on my board.

So My next step is to make sure I have my wires correct but it seems that I have 3 conflicting options, how it came hooked up, how the board is labeled and finally a diagram that doesn't quite match up.

So I've almost completely ruled out the computer as I have tested that it will output to my LCD and I have double checked the pin outs on the vga cable. If there is a wiring issue I believe it would have to be on the chassis connector side. which would mean that it was hooked up wrong all along or that I was mistaken on what the gray and black wire were for.
 

Attachments

  • IMG_3170.jpg
    IMG_3170.jpg
    53.3 KB · Views: 10
  • IMG_3169.jpg
    IMG_3169.jpg
    31.1 KB · Views: 10
  • IMG_3167.jpg
    IMG_3167.jpg
    39.7 KB · Views: 11
  • IMG_3166.jpg
    IMG_3166.jpg
    67.4 KB · Views: 7
One more tidbit I thought I would leave you. I figured at the very least I could see which pins on the chassis were ground so at least that part would be clear. I attached an image of what I measured. I put on lead on the pin and one on the monitor frame and if it came up 0 ohms I marked it as grounded. For full disclosure I used the 20M setting to measure the ohms.
 

Attachments

  • grounded-pins.jpg
    grounded-pins.jpg
    58.4 KB · Views: 7
pic #3 in post 9 is how it should go to the chassis from left to right

pin
1 red
2 green
3 blue
4 and or 7 ground
10 synk

as far as the D-sub coming from your computer i have no idea how it is layed out in the connector.

Peace
Buffett
 
Then I'm stuck. I was really hoping it was a wiring issue on the monitor end of the cable but if you are 100% on that wiring then I have no idea what it could be. I know PC's don't output the perfect signal for monitors but from what I have seen it seems I should be getting at least a distorted image. I figure I can rule out windows and driver settings as those don't apply during bios screens and even during the boot I get a blank screen.
 
I couldn't tell by the pictures, can anyone identify what chassis that is?
 
Back
Top Bottom