Re: Question about Midway Trog boardset

Hi Rodger,

You are probably right. A 10k pull up resistor does pull up the
brightness a little. A 1k pull up resistor brings it up a lot.

When you say "no buffering", aren't the 74ALS541
<http://www.fairchildsemi.com/ds/DM/DM74ALS541.pdf>chips at U2 and U20
doing that or am I getting confused?

Thanks!

Matt

On 1/28/2013 7:04 PM, Rodger Boots wrote:
> 1084S has a 75 ohm input impedance, board can't handle that (no
> buffering). Game monitors are usually high impedance. Pullup
> resistors might help,
>
>
> On Mon, Jan 28, 2013 at 7:04 PM, Matthew Rossiter <matt@rossiters.com
> <mailto:matt@rossiters.com>> wrote:
>
> Hello Everybody,
>
> I have a quick question about a Midway Trog Boardset
> <http://www.arcade-museum.com/game_detail.php?game_id=10201>.
>
> It seems to be working fine but the screen is very dim. The
> logical response would be that it's the monitor. I'm using an
> Amiga 1084S Video Monitor and it's perfectly fine (bright and
> colorful) for any other game, so it has to be the boardset. I
> also tried sending the video to my other flat screen computer
> monitor using an RGB/VGA converter, but the signal drops out
> alot. So maybe it's sending out weak signals. The board
> voltages look pretty good. Pretty much +5v and +12v.
>
> The Schematic for the Video Output sections is here
> <http://www.arcade-museum.com/manuals-videogames/T/trog.pdf> on
> PDF page 55. I'm not much of an expert on Jamma boards. Any
> suggestions?
>
> Matt
>
>
>

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Received on Tue Jan 29 14:37:53 2013