Supergrafx RGB Image Shearing BVM D20F1U

[famiac]

Hi all.

I modified my SGX using the amp on the gamesx website. Much like Chris Covell, i experienced image shearing after the initial mod, but only on my BVM 20F1U. I removed the amplifier as Chris suggested here, but i'm still getting the same problem.

Any idea what might be causing this?



I terminated every single BNC output. Still no dice.
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.
I tried using an LM1881, but i also got the same behavior.

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.

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

Note: I get a nice and stable picture on my two PVM monitors.


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

[svensonson]

I had the same Problem on my bvm-d32 with my snes or so. I cant remember.
anyway, I was able to fix it by turning off the VCR Mode in my BVM Settings
Hope this helps

[famiac]

VCR mode? Where do i find that?

[kamiboy]

I do not think that feature is present on the 20F1 model.

[famiac]

It was in the extended menu. The default password is 1111

It worked!!!!
I actually had to turn VCR mode ON.

Really strange. Thank you svensonson!

[Guspaz]

The manual for this display says of the H DELAY sync button:

"When this button is pushed in (ON), the picture moves horizontally, and a horizontal sync signal appears approximately one quarter in the left edge of the screen."

That kind of sounds like what you're seeing, no? The horizontal sync only happening around a quarter of the way down?

EDIT: The H DELAY button is the SYNC button when SHIFT is off (green lights), while the same buton is the regular sync button when shift is on (orange lights)