Vectrex, line spacing issue

[SnakeGrunger]

Hi everyone,

 

I have a Vectrex of a friend of mine and asked me to do change all its capacitors, which I did, but one problem remained : uneven scanline distribution. Here's a video of the problem :

 

 

As you can see, most lines (in text) and not evenly distributed, the corners on the startup screen logo don't touch either.

 

Here's what I did :

- Replace absolutely all the electrolytic capacitors on both the mainboard and power/video board. (and taking care of soldering on the top and bottom exposed holes that don't have copper going down the via)

- Replace the 5 small styrene caps near the op-amp on the cpu board with film caps of equal capacity.

- Replace all the single-wipe sockets with double-wipe.

- Did the de-buzz audio mod which works very well.

 

Does anyone have an idea of what may be wrong or which IC I should check more closely ?

 

Thanks!

Edited September 14, 2018 by SnakeGrunger

[TopJimmy]

old topic, but i am having a similar issue with my Vectrex.  the power board has been re-capped last year by me.   I opened my Vectrex up this weekend to add a buzz-off audio board, and thought i'd give this issue another look.

 

problem:   text shows what looks like an extra line or line offset ONLY near the bottom of the display.   the rest of the screen text looks fine.   and the rest of the geometry looks ok.   i did adjust the DAC offset pot to zero and have adjusted the other two pots as best as i can.

 

any insights as to what may cause this issue?

 

thanks.