Is there a Defender board mod to allow proper monitor syncing?

fatherpain

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Is there a Defender board mod to allow proper monitor syncing?

Hi guys,

I recently got a Defender, installed a newer Wells Gardner monitor and the image continually rolls vertically. I cannot stop the roll despite adjusting the Vert hold. Additionally the picture is off to the side and horiz position does not adjust it over. I suspect I'm not syncing right though the board is calling for pos H and pos V.

My friend stuffmonger mentioned there may be a defender board mod to perform (cutting some trace) to enable proper monitor sync. Can anyone please point me in the right direction? I'm dying to play some defender and am having trouble locating this fix on the klov search.

Thanks :)

Tom
 
Do you have it wired to the positive H and V sync pins? What type of monitor do you have? Some of the replacement chassis have a switch for sync polarity.
 
There is a modification that can be done to change it from separate positive sync to composite positive sync on the later series Defender boards by cutting a trace, then using pin 7 of the video connector on the CPU for the composite sync. You could invert it to negative composite sync using a 7404.

Early series Defender boards would require a 7486 to combine then invert the sync.

Here is the info if you need it:

http://www.robotron-2084.co.uk/techwilliams2jamma.html#video

I had a Defender CPU that had the same issue as you, and I found that it had already been modified for the composite positive sync. Once I changed the wiring on the CPU video connector and monitor input connector from separate to composite, the picture synced just fine...
 
Thanks Modesitt, that helped a ton :) The boardset in the cab was the older style. .Fortunately I had a later revision boardset with the trace already cut. After swapping in this boardset and wiring it for composite the image finally synced and looks beautiful! Thanks man :D

Tom
 
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