Pioneer CLD-1950

Posted on Feb 5, 2014

This modification is to be done AT YOUR OWN RISK and there is no guarantee that the modification will work for you. Failure to properly install this design correctly may result in damage to you and/or your laserdisc player. This web site takes no responsibility for any modification you may attempt. The following shows a step-by step description on

Pioneer CLD-1950
Click here to download the full size of the above Circuit.

how I modified my Pioneer CLD-1950 laserdisc player to output the Dolby* Digital (AC-3) RF signal needed to drive Dolby Digital demodulators/decoders. My intention is to help those interested in modifying their own player; thereby avoiding the cost of upgrading to a new machine or paying a large sum of money to services that provide the Dolby Digital modification. The custom board shown here holds the required AC-3 circuitry. Once installed, the card enables older, non-AC-3 laserdisc players the ability to output the much talked about AC-3 RF signal. The circuit I used came from Kevin`s web page. Instead of the 2SA1037K and the UN2112 I used the BC808, which is available in Europe. This made it necessary to add a pullup from the base of Q2 to +5VDC, and a series resistor from the same base to the mute input of the board. I used 22k for each resistor, the value is not critical though. This version of the board uses metal film surface mount resistors as well as surface mount ceramic capacitors and transistors to minimize the level of noise in the signal. Players which have the AC-3 circuitry from the factory, typically use surface mount components as well. The card was constructed using a printout from the circuit board program I have written myself. The new circuit card needs two voltage forms (+5VDC, -5VDC) and a ground. Power is tapped from these three lines as indicated in the photo. Red carries the +5VDC; Yellow carries...

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