Just got a blast city with a 2931 monitor- dim screen

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tzakiel
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Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

I've just received a Blast City with a 2931 display and threw in a 15khz Jamma board to test with. The screen is extremely dull/dim. Is there something I can check? The contrast, bright, gain etc are all already set pretty high. I tried unplugging the VGA from the chassis because I thought I remembered that potentially causing brightness issues, which had no effect. Anything else I can try?
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DaveyD
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by DaveyD »

Dont they have a jumper for switching between 15k / 31k which adjusts the screen volts making the screen too dim if you have it the wrong way round?
tzakiel
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

The 2931 is supposed to auto switch. Not sure if that could still be part of the issue though.
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RMRM
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by RMRM »

I don't know the 2931 but what DaveyD says also apply to other Auto Switch chassis, they do sync but the image is too dim or too bright if you don't turn the impedance switch.

The Rodrotron 666 and the Wei Ya work like this.
tzakiel
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

Thanks all. I appreciate the help. From what I have read, no, the 2931 doesn't have or need this type of switch. I did read in the service manual you can adjust a pot somewhere called SCREEN to increase screen brightness beyond what the OSD can do. Not sure if that is wise.
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nem
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by nem »

There's no jumper on the 2931.

You could try turning up voltage on the flyback. Set brightness and contrast right in the middle before.

EDIT: you need to turn it while it is on, only make small adjustments.
tzakiel
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

Thanks... I can try that, I read about a SCREEN pot as well, but I am not sure how to figure out where they are located, or how to adjust them.
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

Update! I turned the B+ pot all the way clockwise (went slowly but didn't see much difference until max) and it made a huge difference. It's still not as bright as I have seen other monitors though. Does this mean my PSU isn't putting out enough power, or anything that this can tell us?
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nem
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by nem »

SCREEN pot is the one on the flyback.

If you have a multimeter, maybe measure what you're getting as input voltage. The pinout for the 15 pin AMP connector is here:

http://wiki.arcadeotaku.com/w/Nanao_MS-2930-S
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

Thanks I see it now. I'll try that and leave b+ back where it was. Is it safe to touch the pots on flyback while running?
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

SCREEN just made the picture quite washed out it seems but not brighter overall. It washed out blacks but didn't boost whites. To me the b+ adjustment looks much more normal. Hmm...
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Shadolf
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by Shadolf »

Could it be that the tube has to be rejuvenated?!
Normaly the "newer" type of tubes don't need to be, but dimm picture could be a sign for an worn out tube, right?
tzakiel
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

Sure, it could be? It does have slight burn in. But overall it seems to be highly related to voltage becuase upping b+ did make a huge difference. For now I've put it back for fear of frying something.
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

Seller is making it right and sending a 2930 free of charge.
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by Asure »

Do you not have this remote board under the control panel?

It's hidden near the back of the control panel area if you flip it over. Saw several blasts with this, and flipping the dip switch solved it.
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by cools »

Asure wrote:Do you not have this remote board under the control panel?

It's hidden near the back of the control panel area if you flip it over. Saw several blasts with this, and flipping the dip switch solved it.
He will once he gets the 2930. The 2931 doesn't have it.
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tzakiel
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Re: Just got a blast city with a 2931 monitor- dim screen

Post by tzakiel »

Asure wrote:Do you not have this remote board under the control panel?

It's hidden near the back of the control panel area if you flip it over. Saw several blasts with this, and flipping the dip switch solved it.
The 2931 is auto switching and doesn't need to be set for either frequency or impedance. The 2930 does have that control for freq.
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