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display shadow/smear

 
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wfk



Joined: 07 Dec 2013
Posts: 2
Location: Amsterdam, NL

PostPosted: Sun Mar 08, 2015 2:54 pm    Post subject: display shadow/smear Reply with quote

Hi all,

I recently tried to boot a NextCube with Dimension board I got some time ago for the first time, using a VGA multisync monitor.
On the first boot, everything worked flawlessly.
However, after I shut down and restarted, the display has started showing persistent severe horizontal shadowing, i.e. any sharp contrasts display a slowly fading smear to the right.

Has anyone here had a similar experience? Is this something that I can fix relatively easily? I'm kinda hoping that it's something as simple as a bad capacitor near the analog output circuitry, but I don't know enough about that sort of analog electronics to have confidence that I can figure this out for myself.

Any help is greatly appreciated.

BTW, looking at the file system time stamps, it looks like this machine hadn't been turned on since 1998...


WFK
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cubist



Joined: 20 Sep 2007
Posts: 246
Location: Cambridge, MA

PostPosted: Sun Mar 08, 2015 3:26 pm    Post subject: Re: display shadow/smear Reply with quote

wfk wrote:

However, after I shut down and restarted, the display has started showing persistent severe horizontal shadowing, i.e. any sharp contrasts display a slowly fading smear to the right.

Horizontal effects generally indicate an impedance problem in the analog video chain. Typically ringing, jitter and simple reflection. Not certain what your problem is, however. But check the usual: video connectors, your 13W3-to-VGA adapter, VGA connector, cables. Check for proper termination on the monitor (75ohm). Flex cables testing for intermittent failures in the signal path.
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barcher174



Joined: 07 Dec 2012
Posts: 559

PostPosted: Sun Mar 08, 2015 5:28 pm    Post subject: Reply with quote

Cabling is definitely the first suspect. However, if it was working and then showed this behavior after running for a while I would begin to suspect caps. In general I replace them now before ever turning on a machine. I love getting the ones that haven't been turned on in a good long while. It feels like opening a time capsule. Smile

--
Brian
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