Yellow picture at start up MS 2931

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LarsVegas
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Yellow picture at start up MS 2931

Post by LarsVegas »

Got some strange behavior on my blast today. Fired it up with a jamma board and got a allover yellow picture. After warming up, it was gone.

Tested with a different board over VGA, same problem. After some time it was gone

Let the monitor stay on for a while and after powering on, everything was normal from start up.

There is something wrong withe the blue channel, when it geht's yellow right?

When I adjusted the picture size and position, the metal bracket was under some light voltage and on the first time, when I moved the joystick the picture was gone, but the monitor still on. When everything worked normal, no game crash and no voltage on the metal. Can there be some short causing this issue?
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grantspain
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Re: Yellow picture at start up MS 2931

Post by grantspain »

sounds like bad solder joint, possibly on the neck card crt socket or perhaps a leaky diode in the blue circuit
as for the remote board short, remove the remote board from its location
LarsVegas
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Re: Yellow picture at start up MS 2931

Post by LarsVegas »

Okay, that sounds manageable. Remoteboard hasn't been mounted to it's place. It's laying around in the CP. Is there a specific diode which can cause the problem?
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grantspain
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Re: Yellow picture at start up MS 2931

Post by grantspain »

most likely the 15v zener on the neck card in blue circuit

perhaps its not even a monitor fault and your wiring is the issue
LarsVegas
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Re: Yellow picture at start up MS 2931

Post by LarsVegas »

This cab is a mess. But it worked well. I will give it some maintenance in new year. Monitor is blurry as hell, awful corner convergence, shadows in the white and geometry is a pain too. Check then the wiring, recap and reflow some solder. Change the diode if needed then. I will report in the future. Thanks Grant, you're such a helpful member and a big enrichment for the community.
LarsVegas
Posts: 65
Joined: November 6th, 2019, 5:40 am
Location: Düsseldorf
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Re: Yellow picture at start up MS 2931

Post by LarsVegas »

Just to give this an update. It seems like the PSU is causing the problem. Made this a VS setup und realized, got only 4.5 V on the jamma connector. Even with the pot cranked up, it's only reaching 4.92V, but the problem was gone after that. Anyway, I will recap the chassis and the PSU. Let's see.
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