Jan 032016

Contra / Gryzor shares almost the same hardware specs with Combat School / Boot Camp, Fast Lane, Flak Attack / MX5000, Haunted Castle / Akumajô Dracula and Trick Trap / Labyrinth Runner.

But among these titles, it is the only game that offers a stereo output thru a 4-pin connector on the board (labeled CN2).

First, you have to select stereo by plugging a connector on CN4 (and put switch 4 of DIPSW3 to off).


The thing is that all the boards I’ve seen still delivers mono sound when you plug this connector (originally brought by Konami and present on the board) on the stereo plug. Why ? Because it doesn’t have the good wiring…

As shown on the picture above, this connector originally comes with pin #1 wired to #2 and pin #3 wired to #4. In that way and plugged on the stereo connector (CN4), it mixes channel 1 and channel 2 from the YM3012 DAC to the LA4445 amp which results a mono output.

To separate the channels, you have to simply modify the connector by wiring pin #1 to #3 and pin #2 to #4.
Now plug it on CN4 and enjoy stereo sound out of CN2. 🙂

There are other Konami games that use the same connector to choose mono or stereo. I’m not sure about the wiring for every game. To my knowledge they are:

– Jackal / Top Gunner
Devil World / Dark Adventure
– Gradius II / Vulcan Venture

– Ajax

Lightning Fighters / Trigon (stereo works without modification of the connector)
– Parodius
(stereo works without modification of the connector)
Surprise Attack (that game seems to have a mono sound design, despite the stereo connector present on the board)

ps. If anybody knows if the original wiring on these boards allows to deliver stereo sound or any other board that is using this connector, I would be glad to know and add it here.

Nintendo Super System – stereo to mono

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Jul 032011

Not really a repair but useful information.
My NSS board by default is set to stereo sound output.
This is no good for me but fortunately it can be switched for mono output via the on board jumper pads and the silk screen clearly states what needs to be done.
Although most people will not need a guide on how to do this, I thought id write it up anyway for just for the sake of it.

Silk screen instruction clearly show for mono output jumpers SL1, 2 and 3 and CL1 and 2 need to be closed.

On my board the CL jumpers were already shorted but non of the SL ones were.

I used a tiny off cut from a recently soldered capacitor to make up small links to solder in and within a couple of minutes all was complete.

The board now outputs mono sound.
I also noticed my BIOS ROM was labelled up “NSS V3” and I am pretty sure MAME only has V2. I dumped it and sure enough it wasn’t recognised by MAME.
Ill have to get it sent off or you can download it here