INTRODUCTION

It has been discovered that there is a mistake in every Dragon's Lair main harness, and it affects the volume controls.
This document has three purposes..

1. To show you how to correct your audio wiring.
2. Show you how to properly construct a volume control harness for a new build.
3. Explain the nature of the mistake and why it should be corrected.

PROCEDURE

Image 1 - "Original" factory wiring for Dragon's Lair volume controls


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The fix...
Looking at the Molex connected to the volume controls, find the wires coming from pins 5 and 6. (See image 1 above)
On mine, one is RED and the other is BLUE.
Where they connect to the potentiometer, reverse them.
You should then have pin-5 connected to the center lead, and pin-6 connected to the side lead. (see image 2 below)
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Image 2 - "Corrected" audio wiring for Dragon's Lair volume controls.

*Note - This is the correct way to assemble a Volume (OCP) Harness, no matter if you have an original factory harness, or a reproduction.

THE FULL EXPLAINATION

"But my machine works fine. Why do I need this?"

Good question. The problem stems from a reversal of two pins going to one of the volume control potentiometers.
Because of this mistake, we are varying the strength of the input signal by shorting it to ground.
Yes, this certainly lowers the volume, but if you turn the volume all the way down, you have tied an active signal directly to ground with no resistance.
This is hard on the signal source, and creates noise to the entire system. Not good.

The correct configuration keeps a constant load on the signal source, and varies the amount of signal going to the main board's amplifier.
It also wires the left and right channels in the same way.


Let's take a look at the actual mistake.
Here is a diagram of the 9 pin audio Molex on the main harness side..

Note that the incoming audio signal from the laserdisc player (red) is being delivered to pin-6, and the CPU pin-16 is getting the output signal from pin-5.

Now let's look at the harness design plan as stated in the Dragon's Lair Schematics...


According to the documentation, the incoming disc audio signal for the RIGHT channel enters the Molex at pin-5, and the volume out signal
leaves the Molex at pin-6, going to the main board at pin-16.
Somewhere between design and production, these two wires got reversed.

"If the mistake is in the main harness at these two pins, why not use a pin extractor and swap the wires?"
Unfortunately, pin-6 is male, and pin-5 is female, so swapping the pins would prevent the Molex from closing.

Changing the wiring at the potentiometer is easy, requires no tools, and takes all of 30 seconds.
So you should make this fix immediately on all Dragon's Lair and Space Ace machines.

However... You are responsible all work you decide to do to your machine. The Author and LaserCon are not responsible if you damage your equipment.
Follow this guide at your own risk, and... ENJOY THE GAME!