In November 1994, when Pioneer announced to the world they would be producing LaserDiscs with 5.1 channel digital audio on LaserDiscs, I was skeptical. The Dolby Surround Digital AC-3 system, which is now called Dolby Digital, was the new audio format and it would occupy the physical area on the disc used previously by the FM analog Right channel. A new LaserDisc player would be required. Further, it would render old pre-digital sound players obsolete as the remaining FM Analog Left channel would only produce Mono playback.
Digital Theater Systems also announced that they too would be developing a home system utilizing LaserDisc. However, the DTS Digital Surround system would provide the same channel configuration at not only a higher bitrate, but it would be fully compatible with the existing LaserDiscs players. All that would be required is a digital audio output on the back of the player. This would allow playback of DTS encoded discs on all LaserDisc players ever made, even ones dating back to 1978. The drawback was the entire PCM audio carrier used for standard 2 channel digital sound would be replaced with the DTS datastream. Meaning if you don't have a DTS decoder, you must listen to the Analog FM audio tracks.
I decided that DTS was the clear and obvious choice and elected not to invest in the Pioneer/Dolby Digital venture. Oops. DTS got started very late, not releasing their first title Jurassic Park until a full two years after the first Dolby Digital title. DTS also has a clear advantage in their system as it can also be utilized on Compact Discs, bringing a full 5.1 channels to the audio only medium which has dominated the recording industry. With their two year head start, Pioneer began belting out Dolby Digital laserdiscs at a furious pace. There are currently over 200 titles in release, with more being released every week. It looks as if I may have made a bad decision on my 5.1 channel support. So, in I decided to buckle under and invest in a Dolby Digital system.
The player pictured here is the Pioneer CLD-D704. I don't have a scan of the CLD-D703. Externally, you can't tell one from the other. In a nutshell, the bulk of the difference between them is the addition of an RF connector for the datastream which houses the Dolby Digital signal. With that in mind, I fell okay about showing this image.
Not wanting to dump my (at the time) 8 month old 703 player for a 704, I began exploring the options to upgrade my CLD-D703. I started in September 1995 by purchasing the service manuals for the CLD-D703 (P/N: RRV1064 [$30] & RRV1066 [$26]) and the CLD-D704 (P/N: RR1244 [$26]). Upon close inspection, and tracing the schematics, I discovered that the board which provides all audio processing is a single board called the AUDB Assembly. The schmetic on the right is a slightly altered version of the schmetic in the CLD-D704 service manual. It has been re-aranged for space considerations, but is essentially the same as that in the Service Manual.
Pioneer also made some minor modifications to the AUDB board just prior to the RF signal being processed. The schematic on the left shows the RF path for both the CLD-D703 (deviations in RED) and what was added for the CLD-D704 (highlighted in BLUE). Based on the RF schematic on the right and the additional modifications Pioneer introduced on the left, I decided the best course of action was to let them do all the work! By design (isn't Pioneer gracious), the AUDB board for the CLD-D703 and CLD-D704 players is based on the same template. The AUDB board from the CLD-D704 will fit into the CLD-D703. All that is really required is to drill a hole in the backplate for the new RCA connector.
Of couse, this presented a small problem. How do you get the RF signal into connector CN123 (labeled SRD) on the AUDB board? Pioneer accomplishes this with a minor modification to the VSOP board to tap the needed RF signal and send it to what in essense is the 2nd RF input on the AUDB. The VSOP Assembly is THE guts of all current Pioneer LaserDisc players. It provides, among other things, the RF signal to the AUDB board for processing. The images on the left and right display the section of the VSOP where this signal is taken. The left image is the for the CLD-D703, with the CLD-D704 being shown on the right. The section where the jumper J24 leaves the VSOP to carry the RF signals to the AUDB for processing is the same. However, the CLD-D704 has an additional jumper for carrying the same RF signal to the Dolby Digital section (marked as SRD & SRDGND on the schematics) of the AUDB. It is clearly the same signal.
So, without the CN123 connector on the VSOP board in the CLD-D703, how would you acomplish this? Well, that is the easy part. Since the signals for both audio systems are taken from the same electrical trace on the VSOP board, it only makes sense you could pick the RF carrier from another source, before it is processed in any way by the FM analog circuits. The signal is already present on the AUDB board in the proper format. By simply adding a jumper from the CN204 connector, to the CN123 connector on the AUDB assembly, a single feed from the VSOP can drive both audio signals. I have to assume Pioneer chose a 2nd jumper from the VSOP because incorporating the necessary trace changes on the AUDB board would have required an extensive redesign. Being cost effective, their decision is understandable.
I purchased the AUDB Assembly (P/N: VWV1419) from Pioneer Electronics Service for $160 (including shipping). When the board arrived, I located the most obvious places to extract the RF signal for delivery to the CN123 connector. Of course directly from the connector CN204 proved to be the most logical location. By constructing a jumper from pins 6&7 of CN204 to pins 2&1 of CN123, the signal from the VSOP could feed both sets of circuits.
Pioneer further proved generious by including an acceptable jumper wire. The AUDB boards ship with a length of wire which leaves J201 of the AUDB and takes the raw headphone audio to the HEPB assembly located at the front of the machine. The jumper is hard-soldered to the AUDB board. Since it is unlikely I will ever use the AUDB board from the CLD-D703 again (and since it is less likely I'll ever use headphones at all), I removed a length of this cable for the construction of my RF jumper.
The image above is the full AUDB board from the CLD-D704. The details are too fine and the raw scan is over 1.5mb
in size for me to use it as a good bed for detailing the RF jumper. I have composed another image which shows the
extreme lower left and lower right corners of the AUDB, which is where all our action takes place. The
blue areas highlight the actual connectors involved. The green
bars indicate the jumper which must be added. Note that on CN204, the RF is on Pin6 with GND on Pin7 and on CN123,
the GND comes first, on Pin1 with SRD (RF really) on Pin2. Proper polarity is very important. Reversing it can
perminantly damage the AUDB board. Care should be taken to not heat the solder points for too long a period. The
electronics on the board are heat sensitive and excessive exposure to the sodering iron may damage them. With this
modification in place, you are ready to mount the new AUDB board into the CLD-D703 player...almost.
By adding a new external connector to the player, a hole must be drilled into the back plate. You may have to move the serial number sticker to another location. The sticker on my player was in the exact wrong spot. Drill a 7/16" hole approximately 5/8" from the top of the back panel and 2" to the left of the of the existing RCA connectors. Exact spacing of the connectors can be done prior to mounting the AUDB board into the player. Further, the RCA connector for the Dolby Digital output is in line with the top most connector (when the board is mounted in the player), so measuring the existing holes can give you an approximate distance down from the top. Since I drilled my hole wrong and ended up filing away at the frame for another hour to get the connector to fit, you may wish to take additional measurements. There is also a tiny hole you can drill to the lower left of the connector which is used to anchor the connector to the back panel. Pioneer does not provide a screw for this when you buy the AUDB board, so you'll have to come up with one on your own. I took mine from a junked ONKYO equalizer.
Once all of the holes have been drilled and board is installed, it's time to hook everything up. The diagram on the right is a modified graphic extracted from the CLD-D703 operations manual. I have added the Dolby Digital connector as well as connections at the amplifier end for Dolby Digital, and DTS Digital Surround.
The modifications you have just completed allow this player to be used with literally any of the LaserDiscs ever made, in any audio format now in existance. From the early days between 1978 and 1985 when there was only analog audio, to today when Dolby Digital is all around us and DTS Digital Surround looming on the horizon, your Pioneer CLD-D703 will play all discs ever produced.
It will not, however, play the new DVD discs. You'll have to buy a whole new player for that. And why would you want to? Pioneer has plans to introduce combination LaserDisc/DVD players which will do everything the current line of LaserDisc players do, but also play DVD's as well. DVD is among us, but its true impact and future are still in question. Many wonder what exactly does it offer us over what we already have? I wonder why introduce a format which will be obselete in less than two years with the introduction of HDTV looming over us.
After finally purchasing a Denon Dolby Digital equipped receiver, these modifications have been put to the test. While there are several folks who have followed the same path outlined above and had their systems work without flaw, I was skeptical this upgrade path would work. With Twister roaring in the background, I can assure you this was worth the price. I am amazed at the audio I hear. I can hardly wait for my DTS decoder...
Based upon reading Kevin Nakano's Dolby Digital upgrade procedure for the CLD-D702, it is unlikely that the upgrade path listed here will work for the other Pioneer LaserDisc players. It is possible however, that this procedure may also be used for the CLD-503. This player may use the same AUDB board, or at least a variation of it specific to the 503 player. If you have any questions or comments on this modification, feel free to contact me.
Updated: November 28, 2010
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