Monitor brighter at the top part IV (put your thinking caps on)

mecha

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Monitor brighter at the top part IV (put your thinking caps on)

okay, tl;dr time again.

I have this one Midway cab (of the War Gods-spraypainted-black variety) where any monitor you install in it has the top inch of the screen that's brighter than the rest. presently it has a WG U5000 in it, until I get off my lazy ass (not really) and head to a UPS store to send my Polo back to Chad for intensive care. the Polo you could actually see retrace lines in this section. now you can turn the brightness down enough to where it's barely noticeable, but this makes the screen too dark to see anything.

I've made probably 3 threads pertaining to this over the past couple years.

I traded out ALL the wiring inside the machine and replaced them with other parts that were working pulls from a KI I got on ebay (for a whopping $10). some encouraged that maybe the JAMMA harness was at fault for this, and I figured replacing the stupid non-iso power block with an iso and using the supplied wiring with it would get it. so, I repeat, the only thing that's the same is whatever's in the coin door and the monitor itself. I replaced EVERYTHING else.

it didn't make a difference, the iso. in fact, I even had ghosting in the picture, but a little snip of the earth ground to the monitor corrected that. why does that happen anyway? it didn't do it with the old non-iso block, but now it does it with the iso. I replaced the cord on it with a brand new one, so why would this be a problem? all the other earth ground wires are connected to where they need to go too. also FWIW, for the first time ever, I actually jumpered the earth ground to the synthetic ground on the screw terminal PSU (also brand new Happ PowerPro)... I think it did the ghosting before I did this though.

now, the last possible item I can think of that's causing the brightness at the top issue has to be the actual top monitor mounting brackets causing some kind of interference or something. the real proof in the pudding would be if I pulled the monitor and tried running it on the floor, but as I already mentioned, I replaced every single wire inside the cab lol, I even changed the power switch.

the marquee light and speakers as far as I can tell have no bearing over this, as I have removed/disconnected them from the machine. the speakers are factory and are unshielded as far as I can tell, and they don't affect the monitor at all where they're mounted, so they probably wouldn't have had anything to do with it anyway. I've even removed the speaker grill, still no change.

the monitor mounting brackets are not magnetized at all. there were no other strange artifacts hidden inside the cab that I saw, so if wood has this kind of effect, then maybe I should donate this thing to science.

thanks for reading if you made it this far. now help me somehow. :)
 
Is there anything running along the back of the tube, between the neck and the top, that might have a magnetic pull? It does sound very bizarre that two different monitors would experience the same problem...
 
that's different.

I'll have to take a gander at that sometime. might have to pull the monitor to achieve it.
 
ok, time for the latest and greatest:

1) I pulled the monitor and ran it on the floor outside of the cab -- problem persisted

2) I hooked the monitor up to another cab (power only, brightness turned up), the problem went away.

3) I disconnected all grounds from the lug, and moved the iso off the ground strap. problem persisted. (see the very end for why this step was pointless :p)

4) did I mention I have replaced every single wire there is in this cab? I even replaced the power cord.. I think, I may or may not have recycled it since I had to cut it and solder it to the line filter/fuse block underneath the iso frame. I originally ran the Midway power block and replaced it with a Midway isolation transformer. these are not the same in any way (I had to swap out all the wiring) and the symptom is identical.

5) I unplugged the marquee. problem persisted.

6) there is no ground running to this monitor, when it was attached I had ghost images, is this symptomatic of a bad line filter? oh, monitor was bright at the top still when the ground was attached and there was ghosting.

as far as I can tell the only thing that's left is the AC input itself... which may or may not be the friggin power cord, I can't remember if I changed that out or not. would that seriously cause this?
 
1) I pulled the monitor and ran it on the floor outside of the cab -- problem persisted

2) I hooked the monitor up to another cab (power only, brightness turned up), the problem went away.

Have you tried another game board in this cabinet ?
(or did I miss that somewhere)

Just wondering if it's some sort of foldover issue coming from the game pcb itself.
I know at least a K7000 will sometimes have a bright looking section at the top if the image is too tall and folds over just right. (not enough to see a double image like typically foldover though) I've seen this on horizontally mounted monitors, so it would be a vertical foldover issue. Just a thought.......
 
Have you tried another game board in this cabinet ?
(or did I miss that somewhere)

Just wondering if it's some sort of foldover issue coming from the game pcb itself.
I know at least a K7000 will sometimes have a bright looking section at the top if the image is too tall and folds over just right. (not enough to see a double image like typically foldover though) I've seen this on horizontally mounted monitors, so it would be a vertical foldover issue. Just a thought.......

does it with multiple games, but for this particular test I had the video signal not even plugged in. it also did this with a Hantarex Polo, and this is a U5000.
 
let me pull em from my phone. it's hard to see on a camera unfortunately.

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U5000, huh? Let me ask you this: Does it do the same thing in both standard and medium-res modes?
 
U5000, huh? Let me ask you this: Does it do the same thing in both standard and medium-res modes?

Leave the video unhooked and swap the res plug (with power off) to see if still does it....
 
Also, does it only happen when the video is hooked up? If so (and you know it's not the cab), then look at that video processing IC...
 
it did it on a Polo too after Chad fixed it for me... that one you could actually see retrace lines in that section that's brighter than the rest.

if you read up, I hooked it up in my KI cab and it went away. I wonder what would happen if I put a K7000 in it...?

so it's something power-related, cause it does it with the video unplugged.

I operated this in my Sportstation for awhile too until I fixed my K7500 (which looks immaculate after the rejuve and new flyback) and it didn't do it in their either.

I made a detailed list above about what I've tried with this so far. lol it's independent of the resolution I'm afraid.
 
if you read up, I hooked it up in my KI cab and it went away.

Actually you said you hooked it up without video and it went away.

so it's something power-related, cause it does it with the video unplugged.

I'm not following your logic. Apparently it was implied that you ran it without video and got this problem, as you mentioned no video with one cab, but never specifically said you got the same problem with no video on the problem cab.


Well, here's your next step: Hook up all the video and stuff in the problem cab, but run the power from the KI cab to the monitor. Goes away? Then it's a power issue or power wiring issue. If not, then hook up the power from the problem cab and run the video from the KI cab. Goes away? Then it's something in the video wiring.

Once you know for sure that it's power, then you should be able to hook up the power from the problem cab to the monitor in the KI and see the same problem, right? After all, if it did it on the U5000 and the Polo, then it's not monitor specific...
 
Actually you said you hooked it up without video and it went away.



I'm not following your logic. Apparently it was implied that you ran it without video and got this problem, as you mentioned no video with one cab, but never specifically said you got the same problem with no video on the problem cab.


Well, here's your next step: Hook up all the video and stuff in the problem cab, but run the power from the KI cab to the monitor. Goes away? Then it's a power issue or power wiring issue. If not, then hook up the power from the problem cab and run the video from the KI cab. Goes away? Then it's something in the video wiring.

Once you know for sure that it's power, then you should be able to hook up the power from the problem cab to the monitor in the KI and see the same problem, right? After all, if it did it on the U5000 and the Polo, then it's not monitor specific...

problem cab:
ran outside of cab on floor, no video hooked up, hooked to problem cab power = bright spot on top

the picture you see was with the video hooked up. so what I'm saying is it is independent of video signal.

KI cab:
ran outside of cab on floor, no video hooked up, hooked to KI cab power = bright spot on top goes away.

so it's something power-related. what I don't comprehend is that I replaced ALL the wiring in the cab and the problem remains.

the problem cab had a shitty JAMMA harness and came with the later model Midway power block that was nothing more than a power cord plug-in, a fuse, and a ground lug.

I stripped every single wire out of this machine. I replaced the JAMMA harness and installed an isolation transformer from a parted-out KI cab (was a parts lot I won on ebay) and I had to borrow some of the old wiring particularly for the marquee fixture from the old power wiring I took out cause the ends were lopped off on the parted-out wiring. I had to use the monitor AC plug from the old wiring too, cause I think the parted out one went to a K7000 (as evident from the white and black wires that were attached with butt connectors -- not the straight violet/violet-yellow wires that Midway used with the isos).

actually, I take that back, the isolation transformer was a pull from the MK2 cab I bought from 7116Aaron, cause the power cord was damaged on his. I installed a new power cord on that MK2 iso and put it in the problem cab... the MK2 got the KI part-out iso lol
 
What is the voltage coming out of the isolation transformer?

Since a U5000 doesn't need an iso, try tapping the monitor power into the iso input instead of the output just to see if the iso is the cause.

Wiring doesn't generate power. This looks like improper power or filtering (either by the filter or the iso)....
 
yeah, but why would a straight AC feed and an isolation transformer produce the same EXACT problem in the same cab?

I know it sounds completely stupid but there's a sharing between the power cord and the monitor connector. that's the only deduction I can make.
 
Well, if you can hook up external power to the monitor and make it go away, then you just need to tap your monitor power into different points of the cabs power (before filter, after filter, before iso, after iso) until you find the spot where it comes and goes. Then you can fix it...
 
well the part that's confusing is I ran it in a non-iso setup and it had the same problem, so I don't think it's anything to do with the iso.

I'll have to dig a little deeper. maybe route the monitor's power wiring differently, maybe try a different connector, cause that's about the only other things I've narrowed it down to.

wonder what would happen if you ran a K7000 in it, something that doesn't have its own power supply built in. strange, I know..
 
Shouldn't matter. You said it's not the monitor, because it works fine when connected to power from a different cab. So, you get an old power cord, put a power connector on one end to connect to the monitor, and jumper wires on the other end. Then connect the jumpers to where power comes into the filter. If you still have the glow, then look at the line cord (assuming you can plug it into a different outlet and still have the problem). If no glow, then connect the jumpers to the output of the filter. If you have a glow, replace the filter. If not, keep going through....
 
I connected the monitor to my KI cab again, the problem carried.

it's something in the monitor.

so am I looking for some strange artifact in the yoke, or maybe I need to adjust the yoke?

the part that doesn't make sense is that Polo had the same problem. what are the odds of that? lol
 
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