Nascom 2 screen offset problem

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Nascom 2 screen offset problem

Postby Lurch666 » Mon May 15, 2017 11:57 am

trying to fix a nascom 2 but a screen problem has me stumped.

In the video I have replaced a faulty prom with an eprom and can now type into the nascom but the display is offset on character to the left.

it should say
but as you can see it comes up
The squares on the right are in the margin of the screen and should not be displayed.
The schematics of the video circuit are here:

I've got quite a way fixing this following data paths to where they stopped to get it this far but this isn't missing data-it just seems to be maybe a timing problem to me.

I have a basic oscilloscope and multimeter but was wondering if anyone here has come across anything similar on an 8 bit system?