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Old 10 November 2011, 20:41   #1
lost_loven
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interlace a3k

Any idea's on a cause for this? Anytime a interlace screen comes on or i try it from prefs, the top half of the screen looks like there is interference. I could try posting pic's if need. thanks.

lost
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Old 10 November 2011, 22:58   #2
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Sounds like a bug in the built-in scandoubler. I have no idea though, I'm only guessing. Does it still happen if you use another output, such as RGB, Composite or RF?
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Old 10 November 2011, 23:14   #3
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hmm I tried other vga monitors but i didn't think to try my 1084s .. will get back to ya on that. good idea!

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Old 11 November 2011, 02:47   #4
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Mine does that also, but on the bottom half. I get odd green lines randomly placed only in Hi-Res Laced Mode on the bottom half of the screen.

It is only on the VGA output, not the RGB. Something wrong in the scandoubler I guess. It rarely shows up in any games or software, though.
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Old 11 November 2011, 05:30   #5
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hmmm.. would something need to be replaced then ? caps? something burning out maybe?

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Old 11 November 2011, 05:38   #6
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Quote:
Originally Posted by lost_loven View Post
Any idea's on a cause for this? Anytime a interlace screen comes on or i try it from prefs, the top half of the screen looks like there is interference. I could try posting pic's if need. thanks.

lost
Theres a adjustment pot for tuning the flicker fixer near the switch on the back,have you guys tried it? it often goes out of adjustment with age. it takes many turns to make a change btw.

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Old 11 November 2011, 05:50   #7
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tried that.. it was my first thought. maybe it the amber chip? is that in a socket?

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Old 11 November 2011, 05:57   #8
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it is in a socket.. maybe give that a quick check out .. dirty connections maybe? reset it? Is this desperate?

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Old 11 November 2011, 15:44   #9
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Amber re-seating may help. But you should also check for battery leakage since a little trace corrosion is all that's needed for this kind of problem. Next thing to check is the +5V Video power supply. It's separate from the main +5V Logic power supply. Good luck!
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Old 11 November 2011, 23:53   #10
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I removed the battery when i got the machine. Fixed and neutralized all the corroded areas too! I didn't reseat the amber because i am to chicken shit to try and pop it out with out the right tools (puller) so i guess i will have to sit on it for a while and make due. not that i use interlace modes that much anyhow.
Here is some pics to show what i was talking about.

lost
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Old 12 November 2011, 18:22   #11
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The images you uploaded do help give a better picture of the problem your having. (But does not really make it an easier problem to fix). It's does not appear to be a PLL tuning problem since the noise is only on part of the screen. I would make a educated guess about a defective RAM chip or a noisy data path to a RAM chip. (There is 384K of RAM used as field store memory so Amber can generate a non-interlaced screen).

It's also possible (but less likely) that you have video noise caused by sync signal distortion but you really need an oscilloscope to verify that problem. You could try a different multi-sync monitor just to see what happens. You should get a PLCC chip puller if you want to try to reseat or replace Amber since the PLCC sockets are easily damaged by screwdrivers... and once again Good Luck!
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Old 27 November 2011, 16:16   #12
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UPDATE!
its not doing it now, I recently install the advance pack of classic workbench and moved the monitor from which was sitting on top to a shelf on top. Funny lines all gone! Wtf lol!

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