Supergrafx RGB Image Shearing

[Vimtoman]

Ok then Steve idea using the LM1881 may sort it out.

or just use composite.

[famiac]

The LM1881 did not help. I still have the same problem. Could there be a problem with the composite circuit? I replaced all of the caps, and as far as i know i didn't lift any traces. The image does work on a different monitor, after all.

It may be worth noting that R159 is missing. I think that normally it should be there. Can anyone check its value?

here's the location

http://picturepush.com/public/14519585

This image is not mine.

[thesteve]

if you are using the din plug, your missing a signal
looks like composite
also looks like 23ohms

[famiac]

Yeah i thought it looked like 23ohms too, but i wasn't quite sure.

I use a modified a din socket. There are only 4 signals. Red, green, brue, and sync. The RGB signals are definitely present, and the sync is there. It's just not working properly on my BVM.

About terminating the outputs:
does every single output on the BVM have to be terminated, or just the ones on the slot i'm using?

[Vimtoman]

Looking at the manual for the monitor you need to terminate the out BNC on all the connections.

I think this should sort it out.

[famiac]

Alright, an update for you guys.

I terminated every single BNC output. Still no dice.

I figured a couple more things out.
I removed the LM 1881, and fed the pvm pure sync from pin 44, using this circuit:
http://console5.com/wiki/File:Hu6260_RGB_Amplifier_Schematic.png


Same issue.
The shearing jittered a little bit back when i had the lm1881 in, but now it's back to how it was before.


I discovered that the shearing happens on all other channels as well! even when the pc engine's input card isn't selected. This could be a clue. Note: this only happens with my supergrafx

More pics:
http://imgur.com/a/atmSd


Edit:
I also get the exact same behavior when i use a t connector to combine the sync and green and set the bvm to use internal sync.

[Vimtoman]

Can you try the composite sync

[thesteve]

a few points
1 the amp you used doesnt increase the sync pulse, so it wont help
2 have you tried composite video on that screen (can you)

[famiac]

It was resolved. The BVMs sure are picky

The details are here:
http://shmups.system11.org/viewtopic.php?f=6&t=55732

[Vimtoman]

Well done.
 I guess it's down to dicky VCR's in Ye old days. E ayre missus.