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CPS3 sound and video issues

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ebzero89

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Hello all, finally got around to having a full session with my CPS3 board playing 3s yesterday and found some sort of intermittent issues. First, the sound works sometimes and sometimes will cut out. Switching audio from external to JAMMA and back fixes for a while but then it dies again. Using external audio in general works for a while, but then one of the channels will suddenly die out and stay that way until I have the power off for a bit. To me it feels like a heat issue and an amp going bad, but I'm not sure where to start on fixing it. Any ideas on what I should change out in the area? I see several caps around there that are perilously bent/loose, so that may be a place to start.

Second issue is that there is some bowing in the center of the screen like the geometry on my cab is bad. After we switched games to something else rather than deal with the sound issues, I swapped my CPS2 into the cab. Sound works great first try and there's no geometry issues. Where should I start with trying to troubleshoot this CPS3 board?

Thanks in advance for your help!
 
There is a good chance your volume potentiometer is either dirty or needs replacing. Pretty common problem on them.

I would try cleaning the volume pot first.

To clean the pot spray some electrical contact cleaner inside of it/under it and turn the knob fully clockwise and counterclockwise a few times. This should clean it up if your pot isn't fubar'd.
 
Ok I'll give that a shot and see how it goes. Any ideas about the video geometry? Like I said that doesn't happen with the cps2 so it's likely something with the board.
 
So as a bit of an update, I cleaned out the volume pot, and also noticed that capacitor cx6 is just straight up broken off the board. It's a 1000uf 25v cap. Is this part of the audio circuit that could be causing the problem? I'm going to fix it anyway it's just be nice to know it's something obvious.
 
So replacing that cap appears to have fixed the stereo audio. So that's 1 problem down!

The convergence on the video is the next thing. Here are some pictures.

CO4NxJr.jpg


YDp9qhe.jpg


rIYN3mL.jpg
 
Convergence is typically a monitor issue. Different boards have different resolutions so the fact you didn't have the same issue on your CPS2 may not be relevant. That's why monitors have adjustments.

Either way whether it's monitor or board, cap replacement is in order. Since you've already replaced the large audio cap, might be worth replacing the other electrolytics on that board.
 
You're probably right. I'm a bit skittish to do a cap kit on my monitor chassis as 2931's are exceedingly hard to come by at the moment. So I can live with it until I have a backup in place. Thanks for you guys help!
 
Haha Haha that'll teach me to complain before googling. Literally the first result is about someone saying that the 2931 has side compression in 15khz.
 
ebzero89 said:
Haha Haha that'll teach me to complain before googling. Literally the first result is about someone saying that the 2931 has side compression in 15khz.
Click to expand...
I don't think the 2931 has that much side compression. It has some, but honestly it's very hard to see unless you're looking at a grid. Anyway, your geometry is definitely off. Hit up the extended menu and adjust both side pincushion and corner distortion. The extended menu can be accessed by holding down on the monitor remote for a few seconds. The adjustments you're looking for are SPC and CORNER.

You won't be able to fix corner convergence by doing this though, so the corners will look out of focus and the colors will be off.
 
Yeah the corner convergence is a different thing. I was more wondering how to fix the bowing in the middle which I guess is side compression. I'll have to get some strips or something to fix the colors in the corners I think.
 
Kind of necroing my own post here, but I did end up getting the pincushion adjusted and that worked out pretty well, but the corners evade me. No matter what I do, the left hand side of the screen isn't in line with the right hand side on the bottom. There's a sort of upwards slope to the bottom of the screen that's fairly noticeable and a bit annoying. You can see it pretty well in this image on the 3rd strike machine. Would a recap help this? I finally got my other 2931 back from repair (but haven't tested yet). May wait until after this weekend to swap the boards out and do a recap if it'll help.

UOIIE1b.jpg
 
This is a well known issue on the trisync monitors in 15k mode. You can get it close but not perfect

The NAOMI supports 31k so it shouldn't have the same issues
 
An upwards slope at the bottom of the screen is standard on trisync monitors? I've heard of side compression but that's a bit out there...
 
ebzero89 said:
An upwards slope at the bottom of the screen is standard on trisync monitors?
Click to expand...
Well, no. It has nothing to do with it being trisync.

Most likely you're missing a permalloy strip or even a magnet from the yoke. It's a common issue with this monitor.

See this thread:

Nanao ms-2931 buzz (fixed!)

Unless you want to reconverge the whole monitor, you'll have to learn to live with it.
 
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