Pioneer CLD-A100
AC3/ Dolby Digital Upgrade for Laserdisc Player

Adding a AC-3 RF OUT to a Pioneer CLD-A100

The modification was provided by Jerry DaSilva at JCD4878@rit.edu.
The email address is no longer valid. Jerry if you are still around I hope it's OK to print your details.

This page will attempt to show you how to add a AC-3 RF output jack to the Pioneer CLD-A100 Laseractive laser disc player. The circuit described within has been built and tested to work on my CLD-A100 and a Pioneer VSX-99 AC-3 Decoder/Receiver with no problems. I do not guarantee it will work for you, though. For one thing, messing with electronics when you do not know what you are doing can seriously damage them. Therefore, I highly recomend you do NOT do this modification yourself unless you are a skilled electronics professional or hobbyist. If you really want to do this to your player, and you do not feel you are skilled enough to do it yourself, bring it to a friend or shop with these plans to get it done by someone who has the experience to do it. Finally, if anything blows up as the result of performing any of these modifications, It is not my fault. Do this modification at your own risk! Make sure you read these instructions in their entirety before doing anything.

Building the AC-3 circuit for the Pioneer CLD-A100

Shown above is the AC-3 circuit I built on a homemade single-sided PC board. You can build the circuit any way you want. I choose to build it as above to make it easier on me to mount, and so it would look half 'nice' when installed. I highly recommend you make a PCB for the circuit. The board is approximately 1.75" x 0.5625" in size. I'm sorry I cannot provide a actual size PCB layout. I originally drew the PCB layout right on the board using a permanent marker and etched. I never drew it out on paper. You should be able to approximate my board design from the above images and the following schematic. In my pictures: RED is -5V, WHITE/GREEN is AFM, BLUE is +5V, and BROWN is GND.

The schematic diagram on the left was derived from the original AC-3 upgrade circuit schematic obtained from http://users.aol.com/chunter/ac-3mod.html. I modified it to clarify the original circuit, and to specialize the schematic for specific use in a Pioneer CLD-A100 player. One difference you'll notice is that I dropped the MUTE circuit completely. This is because the AFM signal in the CLD-A100 already mutes itself when in STOP and PAUSE mode. I also dropped the 75ohm coax cable from the design because the AFM signal in the CLD-A100 was so close to the back panel that I was able to build the circuit right next to the output jack while keeping the AFM signal wire short.

Here is a parts list for the AC-3 circuit built, all of which were purchased at a local Radio Shack store.

1       1/4 watt 680 ohm resistor

1       1/4 watt 75 ohm resistor

1       1/4 watt 10,000 ohm resistor

1       1/4 watt 100,000 ohm resistor

2       0.1 microFarad ceramic capacitors

1       MPS3904 Transistor

1       Panel mount RCA jack

Adding the AC-3 circuit to the Pioneer CLD-A100

Keep the following in mind when you are reading through the instructions:
1. All the accompanying pictures on this page a thumbnails. Click on the thumbnail image to get the much larger detailed image.
2. The bright red lines and such on some of the images were drawn on there by me. They are not part of the original image, just in case you freak when there isn't a red circle on your player where my image shows one. The red lines and such are for clarifying steps.
3. Be aware of static electricity. Wearing a static discharge wristband is a very good idea. You do not want to kill your player because of a silly spark jumping from your finger.
Ok, now lets get to it.

The left image shows approximately what the final product will look like after the modification is added (Yours will probably look different depending on how you build it). I put a red box around the new jack for clarity. Yes, you will have to drill the case. If this makes you nervous, stop now! First we need to open the player up. Before we continue, I recommend you remove any Laseractive paks that you might have in the Pak port first. No sense risking blowing up a Pak along with the player if something goes wrong. take out the two black screws on each side of the player out. Then remove the five silver screws out along the back left, right, and top edges of the case. The cover should now slide easily. Slide the cover back a little and then pull the two sides out so you can lift the cover straight up off the player.

You should now see the image to the left, pending Pioneer did not make any serious design changes. I have circled the four screws you have to remove next. MAKE SURE TO DISCHARGE ALL STATIC ELECTRICITY FROM YOURSELF BEFORE TOUCHING ANY CIRCUITRY! Remove these screws and take the white plastic sheet off the back of the board.

You should now see the image to the left. Swing the board out as you see it in the next picture for the next step. There is a white clip on the right rear corner of the player, when you are facing the rear, attached to the board below the green board you are swinging up. You can rotate this clip up to hold the green board upright. Slip the rear corner of the green board into the white clip, and slip the front corner of the green board into the black plastic slot on the front of the player where you removed one of the screws that holds the green board down. I have circled the clip locations on the following step's image.

The main green board should now be standing up on its own as shown in the image to the left. I have boxed the area of the board of interest in red. This is the location of the AFM signal we need. A blown up detail follows in the next step.

This is the analog audio decoding section where you can find the AFM RF signal before it is processed into left/right channels by the CX chip. You can tap everything you need for the AC-3 circuit from this section of the board.

If you use a large enough gauge wire, you can solder all the wires to the board right through the jumper wire holes. As you can see in the picture, that is what I did. Solder a wire through the indicated -5V jumper wire hole. In my case, I used a RED wire for this. Solder another wire through the indicated GND jumper wire hole. I used a BROWN wire for this.

Solder a wire through the indicated +5V jumper wire hole. I used a BLUE wire for this. Finally, solder a wire through the indicated unmarked jumper wire hole. I used a WHITE wire for this.

The rest depends on if you made a PCB for your circuit like I did or not. If you built a PCB like mine, you need to drill three holes in the back panel of the player to mount the board. This is a BIG pain, since you need to remove the back panel of the player. DO NOT TRY TO SHORTCUT THIS! I warn you because I made the mistake of trying to shortcut it by trying to drill a 1/2" hole into sheet metal thinking I could 'catch' the drill bit punching through before it worked its way to that PCB in the player about an inch away from the puncture point. It didn't work (imagine that), and I had to shell out $110 to Pioneer to send me the PCB I snapped in half with a drill bit. So unless you want to make this upgrade a expensive venture, I'd take the trouble to get the entire back panel off of the player before you drill it. First drill a 1/2" hole approximately in the position showed in my above pictures. You can then place the PCB you made with the jack through the 1/2" hole flush with the panel. Make sure the jack does NOT touch the back panel. The jack must not short against panel ground, or you will bypass the AC-3 circuit's capacitor between the panel ground and the jack's ground. Once you got it lined up, you can centerpunch the mounting holes on the panel through the mounting holes in your PCB board. If you do this carefully, the jack will not touch the panel when you mount the PCB to the panel. Now mount the rear panel back onto the player without the PCB mounted to it.

Finally, all you have to do is solder the four wires to the appropriate points on your PCB board, and then mount the PCB to the back panel through the holes you made for it. That's it. Before closing the player up, I recommend you test it completely. This includes all sound modes, digital and analog. Be sure everything works the way it did before. You can do this with the main green board propped up on the plastic clips. The player was designed so it can work with the board folded up. Careful not to touch or drop anything on the laserdisc while it is spinning. That disc has the potential to cause some major harm when it is spinning that fast. Just imagine what would happen if you shattered that laserdisc while it was spinning! Make sure to test the AC-3 output jack you added too. If you don't have a AC-3 decoder yet, find a friend who does and trusts that your player won't blow up his/her decoder. If everything works ok, close it up and enjoy! Congrats!, you're now a owner of a AC-3 enabled laserdisc player.