How-to: Sony MXD-D5C Minidisc / CD Changer deck, modified to add TOSlink optical and Coaxial S/PDIF outputs

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This is my photographic How-To guide to adding S/PDIF digital audio outputs to my Sony MXD-D5C, which was equipped from the factory with only analog outputs. No soldering to the deck is required This guide is intended to be the companion thread to my earlier discussion:

...which in turn was inspired by:

...as well as:

Adding a Digital out to MDS-JE330

Adding Digital Optical Output to a Sony MDS-JE440 Minidisc Deck

Digital Optical Output Mod for Sony MDS-JE470 Minidisc Deck

...which I found here:

Construction projects: Adding Digital I/Os

LET'S BEGIN!

Sony MXD-D5C, North America model:

Goal: to build four working S/PDIF digital audio outputs, featuring a relatively clean-looking installation:

***DISCLAIMER***

WARNING: Do Not Attempt. Working with electronic equipment can be hazardous. There is a great risk of electric shock. You do not want to get The Shock. Furthermore, static discharge from simply handling your components can render your equipment useless. I cannot be responsible for damage or destruction to your equipment, reversible or otherwise. I cannot be responsible for Death, Injury, or Insult yourself or others may sustain while attempting to modify your own gear or that of others. The methods described here worked for me, but your equipment and experience may differ. This will void your warranty.

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Background: I've had this Sony MXD-D5C 5-CD Changer / Minidisc deck for over ten years, and even though I love this unit, I have always been frustrated by the lack of digital audio output on this deck. Although I don't listen to a lot of MD's anymore, this deck is my primary CD Player in my aging home audio rack (I love the 5-CD changer). This guide will depict my successful attempt to add S/PDIF TOSlink optical and coaxial digital audio output myself. Having read the "hacking" pages of Minidisc.org many years ago, I know there are still (as of this writing) How-To articles online for adding TOSLINK outputs to certain Minidisc decks which were not equipped with S/PDIF digital outputs from the factory (see links above). However, none of these articles described the MXD-D5C specifically. I thought the internal components might be similar enough that those earlier guides would be virtually identical to what I would carry out myself, but alas, this did not turn out to be the case. However, after studying the Sony MXD-D5C service manual schematics for a few days and having extended and extremely helpful online discussions with sonyinsider.com forum administrator and fellow MXD deck owner Stephen sfbp, I was finally able to discover that getting the digital outputs would ultimately be quite easy. I am no electrical engineer, but am merely a tinkerer who likes to "hack upward" the things in my life which I feel can be upgraded with a bit of ingenuity. The "figuring out" part of the project was probably the most challenging aspect for myself, a non-EE hobbyist... followed closely by the rear-panel modifications in which I attempted to make the deck appear factory-equipped with digital outputs in the end.

I had also initially hoped that I would be able to simply use one digital output for both MD and CD digital audio streams. However, not only was there no single connectable point where both CD and MD SPDIF digital audio signals would be autoswitched according to the transport in use, it was also impossible to mix the two circuits into one output cable (I did test this). With this knowledge, I decided to go all-out and make optical and coaxial connections for both MD and CD transports for maximum connective flexibility, bringing the total number of digital audio outputs to four.

Some of the materials I was able to easily find at my local Radio Shack retail store. Some parts I already had lying around, but the TOSlink transmitters TOTX177AL had to come from a specific online source (http://www.digikey.com/). More on these parts soon.

Here is a fairly comprehensive parts list for this mod:

1x Sony MXD-D5C Minidisc Recorder / 5-CD Changer Deck:

1x Sony MXD-D5C Service Manual

2x Toshiba TOTX177AL(F,T) TOSlink Transmitting Modules with integrated dust flap and screw-mount hole (order a couple extra - you will be soldering directly onto these inexpensive but delicate components. 10+ Qty. discount): Digi-Key Corporation (TOTX177AL Data Sheet)

1x 4-pack RCA Phono Panel-mount Jacks (only 2 jacks used): Radio Shack

1x 4-Position Dual-Row Barrier Strip: Radio Shack

2x 2-pack 0.1µF Ceramic Disc Capacitor (4 capacitors total needed) (cap code "104"): Radio Shack

1x 5-Pack 1/8-Watt 330 Ohm Carbon Film Resistors (2 resistors needed) (color code "orange-orange-brown / gold"): Radio Shack

1x 5 Pack 1/8-Watt 150 Ohm Carbon-Film Resistors (2 resistors needed) (color code "brown-green-brown / gold"): Radio Shack

2x 22-18 AWG 1/4" Female Disconnects: Radio Shack (size needs confirmed)

2x 22-18 AWG #6 Stud Size Insulated Ring Terminal: Radio Shack (size needs confirmed - it fits around the threaded base of the coax jack, and the inner diameter is 1/4" or about 7mm. Marked "2 - 6" on the part I used)

1x 16-Pack #6 Insulated Spade Terminal: Radio Shack (size needs confirmed - small, narrow spade connector, inner distance between prongs is slightly less than 4mm. Marked "1.25 - 3.5L" on the part I used)

Heat-shrink tubing suitable for ~26 Gauge wire: Radio Shack

24" (60cm) x4 Colors (Red, Black, Yellow, White, etc.) 26AWG Multistrand wire (I used several 12V Power Extension Wires with Mini Pin and Socket connectors at either end, similar to these PC Fan Extension Cables at Newegg.com or even better, these Y-cables).

2x Size 8 0.5" (Very small) Steel Sequin Pins: Joann Fabric and Crafts. (Maybe there is a better true electronics component for this, but pins similar to these worked for me. Be sure you don't use a type with a plastic head, as you will be soldering directly to these very small pins).

1x 10-pack 6-32 x 1/2" Round Head Machine Screws and Nuts

1x 10-pack 6-32 x 1/2" Flat Head Machine Screws and Nuts

2x Small-diameter Round Head Sheet Metal Screws (sized appropriately for mounting the TOSlink transmitters)

1x Piece approx. 6"x2" x 1/16" or 1/32" thick Sheet Steel or Aluminum (I used a scrap pop-out drive bay cover to an old ATX PC case)

Here are some tools and consumables I used for this project:

Clean working space with plenty of good light

Grounding Strap: Radio Shack

Electronics and Hobby Miniature Soldering Iron Kit: Radio Shack

1oz. .015 diameter "High-Tech" Silver-Bearing Solder" Radio Shack

2 oz. Canister Non-Spill Rosin Soldering Paste Flux: Radio Shack

Butane Micro-torch: Radio Shack

Mini Diagonal Wire Cutters: Radio Shack

Mini Needle-nose Pliers: Radio Shack

Wire Stripper/Connector Crimping Tool: Radio Shack

Dremel Rotary Tool with a stack of cut-off discs and an assortment of grinding wheels: Amazon.com

3M Scotch 23 0.75"x30' Pliable Rubber Splicing Tape: Amazon.com or Mouser.com

Drill or Drill Press with an assortment of sharp metal-drilling bits

Mini bench vise

Scissors

Tweezers

Magnifying Glass

Phillips and Flathead Screwdrivers

etc.

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Unplug your deck from power and audio connections and carefully bring it to your flat, clean and dry work area.

Use a Phillips head screwdriver to unscrew the 6 black painted screws which affix the top cover to the deck. There are two black screws on the rear panel along the upper edge, two screws on the left panel of the deck, and two screws on the right panel as well. Set them aside in a safe place where they will not get lost:

Carefully lift the top cover panel off of the deck and set it aside in a safe place where it will not get scratched or bent. Use caution when removing the top panel so as not to have the front edge bind up against the fragile front panel. The top panel is metal and has very sharp edges - handle it very carefully such that you do not cut yourself. The deck itself also has plenty of sharp edges as well. This is the first view of the inside of the MXD-D5C:

We can clearly see the large CD-changer mechanism dominating the left side of the deck, while the right side houses the truly "mini" Minidisc transport mechanism, power transformer, Main Circuit Board, and the smaller Audio Board slightly above the Main Board at the rear.

The smaller audio board is connected to the rear panel of the deck by three screws near each connector jack. Remove them and set them aside with the screws removed earlier.

Unplug the white keyboard connector from the audio board by carefully lifting straight up so as not to bend or break the pins:

Close-up view of the Audio Board's ribbon wire Connector CN305, which we will soon be tapping for digital audio signals:

Very very carefully remove the audio board by gently squeezing the tips of the 2 plastic support prongs with mini-needlenose pliers and lifting the Audio Board up. Use extreme caution. You may wish to also carefully remove the ribbon cable from Connector CN305 such that the audio board may be set aside without flopping over in the way on it's own (the ribbon cable is delicate yet springy). Remember to always wear your anti-static strap and carefully handle this board only by its edges, never touching the electronic components which are soldered to it. Here is a close-up of the audio board after it has been removed from it's supports:

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Now is a good time to have a look inside the MXD-D5C Sony Service Manual:

This is a wonderful resource for learning about how this deck operates. When it comes down to it for this project, though, we are really looking to tap 4 connections:

+5VDC (This will supply power to our two TOTX177 TOSlink transmitters.)

GND (One ground connection is required for each of our two TOSlink transmitters as well as for each of our two coaxial output jacks)

SPDIF0 (Minidisc digital audio output which will get split to one TOSlink Transmitter and one coaxial connector)

SPDIF1 (Compact Disc digital audio output which will get split to one TOSlink Transmitter and one coaxial connector)

(We'll look at this circuit diagram in a little bit.)

Where can we find these 4 connection points inside this deck? First off, we are looking for +5VDC and GND. Page 61 is where we'll start. This is the 2nd of 4 schematic diagrams of the Main Board. This particular schematic does not depict the board as we would look at it in the deck, but rather it shows which paths the circuits make. Although it is not the only location depicted, +5VDC and GND are conveniently located on the #1 and #6 circuits of Connector CN800 (For Check), which is an unused connector and will be very easy to tap:

On page 58, we see the Main Board exactly as we would looking down into the deck. We will want to tap the #1 (GND) and #6 (+5VDC) pins of Connector CN800:

A closer view of the printed circuit at CN800:

Before we do any wiring, lets look for our S/PDIF digital audio circuits. Page 66 shows us the circuit schematics of the Audio Board, and Connector CN305 passes along SPDIF0 (MD) and SPDIF1 (CD) signals from the ribbon cable to the on-board audio processing:

A closer view of CN305 on pg. 66 reveals that the MD audio is on circuit 1, and the CD audio is on circuit 3:

On page 64, we see the Audio Board as we would looking down into the deck. We will want to tap the #1 (SPDIF0 for Minidisc) and #3 (SPDIF1 for CD) pins of Connector CN305:

It's a good time to look at our circuit diagram for our mod. It's really quite simple:

You'll notice that each jack requires one or more additional components. The TOSlink connectors each require a 0.1µF capacitor between the Power and Ground leads, according to page 2 of the TOTX177AL data sheet:

The coaxial connectors require a few components each, according to Robert Meyer-Piening's Adding a Digital out to MDS-JE330 How-To page, referenced near the top of this guide. We'll have a look at the coaxial circuits soon.

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Let's start building our circuits.

According the the TOTX177AL TOSlink transmitter datasheet referenced above, I needed to place a 0.1µF capacitor between the power and ground leads, within 7mm of the transmitter led emitter.

This proved to be a task requiring delicate soldering. I soldered the capacitor to the TOTX177 leads by making tiny loops with the leads of the capacitor, such that the loops would slide over the transmitter leads but not contact adjacent leads:

Snipping off the excess leads of the capacitor:

Soldering a capacitor to one of the TOSlink transmitters:

I did this for both TOSlink transmitters, then set them carefully aside. Next I turned to the coaxial jacks. Instead of soldering directly to the jacks, I wanted to have the flexibility to disconnect the leads for installation, servicing etc. I found that a ring terminal (for Ground) and a quick-disconnect (for SPDIF Signal) worked nicely:

I have modeled my coaxial output circuit on Robert Meyer-Piening's Adding a Digital out to MDS-JE330 coaxial jack circuit diagram. Each coaxial connector utilizes a 0.1µF capacitor in series with a 330-Ohm resistor between the SPDIF signal source and the center post on the RCA-Phono Jack. Additionally, a 150-Ohm resistor is placed between the Signal post and Ground ring of the RCA connector. Multistrand 26AWG wire is a nice working size. Seen here is one of two coaxial circuits prior to soldering:

...and again after soldering, with heatshrink tubing ready to fit in place to insulate the bare metal leads of the circuit:

I built twin versions of this circuit and joined the ground leads together on the two coaxial outputs. The opposite end of the leads gets a crimp-on ring or spade connector, which will fit on the 4-Position Dual-Row Barrier Strip that I used as a distribution block:

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Next we are going to tap into the four contacts that we require within the deck to supply our digital output jacks:

For the tapping of each SPDIF signal from Connector CN305 on the audio board I soldered and heatshrinked a 12-inch length of 26AWG multistranded wire to a 1/2" size 8 steel sequin pin:

I used extreme care when inserting these pins so as not to damage the connector nor the ribbon cable. Once in, however, they are held firmly in place and make an excellent connection between the ribbon contact and the connector contact.

Next I tapped Ground (contact #1) and +5VDC Power (contact #6) inside Connector CN800 on the Main Board. This connector is located directly underneath the Audio Board and is the reason the Audio Board was dismounted from it's support prongs. This connector is normally vacant, without any ribbon cable in it. I needed a slightly larger pin size to tap into this connector than the two I used on CN305, such that my wire fits securely with gentle pressure. For this I dismantled a spare PC case fan power cord with miniature 12V pin-and-socket connectors. These pins were just a bit too large for connector CN800, so I filed them down a small amount until the fit was just right. Heatshrink was applied over the extended bare metal of the pins such that they do not short out against one another. The opposite end of each wire was snipped of its unneeded Molex PC connector and stripped to fit a crimp-on spade connector:

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Now we have two TOSlink transmitters with their 0.1µF capacitors soldered in place, and two RCA-Phono coaxial jacks with their associated components soldered in as well. I connected test leads to all associated connections and verified that each jack was putting out a digital signal. Good news, my circuits work

I used a 4-Position Dual-Row Barrier Strip to split the incoming single SPDIF0, SPDIF1, +5VDC, and GND wires amongst the output connections. If I were to do this project again, I would probably eliminate this part, and instead crimp each of the same Signal, Power, and Ground wires into fully-insulated quick-disconnect connectors for a cleaner, easily dis-connectable arrangement. However, the part works fine and was inexpensive. You can see my test bracket here:

You may have noticed the power and ground wires with very small connectors fitted on the leads of the TOSlink transmitters. These were extra wires in my PC parts bin that I put to use.

I don't know what they are called, but the similar-but-slightly-larger 12V PC Fan Socket Connectors should fit just about as well. Most 12V PC Fan connectors seem to have three leads per socket connector, which is perfect for our TOSlink transmitters. On my transmitters, I had to use a separate third lead for the SPDIF signal... a three-conductor socket would make for a cleaner installation, but the arrangement I have performs fine.

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Next will be the fitting of all the output jacks to the rear panel of the deck and routing the final wiring harness. I marked up the general blank area where I wanted to have the output jacks emerge from the rear panel of the deck:

Next I disconnected the yellow mains power cord connector from the Main Board and removed the 7 rear panel screws to release the rear panel from the deck:

I started determining more precisely where I would be placing the output jacks by lightly penciling the zone where I'd be drilling holes in the rear panel, beginning with markings that align approximately with the factory analog output jacks:

Spacing of the jacks is going to be important. The width of two typical TOSlink connectors is greater than the width of two transmitters side-by-side and needs to be accounted for when determining jack placement:

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I mounted all the output jacks to a small steel plate such that there would be a bit more flexibility with mounting and removal of the digital outputs for servicing. Using a separate mounting plate instead of mounting the connectors directly to the back panel of the deck would also spare the deck's rear panel from heavy cutting and grinding (in theory, anyway LOL).

This is the steel plate I will use to mount the four digital outputs jacks and barrier strip distribution block. It is an unused pop-out drive bay cover for an old desktop ATX PC case:

I aligned the marks that I traced on the rear panel of the deck to the steel plate. Then I drilled mounting holes for the RCA-Phono jacks and used my Dremel Rotary Tool with cut-off wheel to cut two "H" shaped channels which are going to be used to mount the square TOSlink connectors:

In addition to the holes for digital output jacks, I drilled holes for the mounting screws for the barrier strip distribution block. These holes need to be countersunk such that the tapered head of the barrier strip mounting screw will sit flush against the plate, since the plate will be mounted flat against the rear panel of the deck:

On the rear of the plate, I used the Dremel cut-off wheel to carve a notch along the outer edges of the "H" shapes. These notches are not cut all the way through the metal because I need to make a sort of "Barn Door" flap. The notch will make the flaps a bit easier to fold back:

A small hole is drilled and a mounting screw affixes each TOTX177AL to the plate:

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I temporarily removed the TOSlink transmitters from the mounting plate and placed it on the deck's rear panel to verify the position of holes to be drilled:

I used hopelessly dull drill bits which made this part of the job much more difficult than it should have been. Two small screw holes are drilled to mount either end of the plate, two 1/2" holes are drilled for the RCA-Phono jacks, and two larger holes, approximately 3/4" inches diameter, are drilled and shaped with a grinding stone for the TOSlink transmitters. The upper edge of the TOSlink holes needed to be elongated to allow for the TOSlinks' mounting screws:

I used a large permanent marker to "paint" black any bare metal that would show:

The barrier strip distribution block gets mounted to the mounting plate with flatheaded screws:

TOSlink components in place:

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Fitting the RCA-Phono coaxial jacks to the mounting plate:

We can see the need for the elongated TOSlink holes with the transmitter mounting screws in place:

I wrapped additional insulation (3M Scotch 23 0.75"x30' Pliable Rubber Splicing Tape: Amazon.com or Mouser.com) on the coaxial circuits due to some exposed metal that the heatshrink tubing could not cover:

Connecting the coaxial circuits:

Mounting the plate to the rear panel with nuts and lock washers:

TOSlink leads fitted:

Label Baby Jr. provides a visual cue on the distribution block. I have made the top row the "input" side, and the bottom row can be considered the "output" side:

The rear panel is also clearly labelled:

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Rear panel is now ready to be replaced onto the deck:

Here we can see how the mounting plate and wiring fits inside the deck:

The +5VDC, GND, SPDIF (MD), and SPDIF (CD) supply leads are connected to the top row of the distribution block:

All wires are now connected.

Reconnect the mains cord - we are almost finished!

About to test the digital output connections to my A/V receiver - happy to report that all four digital audio outputs tested perfectly:

The top cover was replaced (do you remember where you put those screws? ), and I decided to use the TOSlink connections to my A/V receiver for it's final hookup:

FINALLY our MXD-D5C deck is settled back into it's place on the A/V stand, in full SPDIF digital audio output glory

IN CONCLUSION:

If you've made it this far, boy, then congratulations to you! I cannot express how thrilled I am with this mod, and I hope others can learn and improve upon what I've done here. I know now how I'd simplify a few things if I were to do this again, but it all worked out in the end.

I do have one small issue with my new digital audio output connection - but it is a shortcoming of the A/V receiver, not the mod to the deck. During playback of CD's, which often have a two-second space of silence between tracks, the receiver momentarily loses the digital S/PDIF signal lock. When the next song begins, my receiver takes about a quarter-second to re-lock the signal again before it plays the audio stream, so I often miss the first beat of music after the two-second silence. However, this is also true when playing back the same CD's on my Panasonic DVD player when connected via TOSlink to the receiver, so I know it's not the fault of the MXD-D5C Digital Audio Output Mod. I am hoping a newer receiver will solve this issue in the future. Input on this issue is very welcome.

I cannot thank enough the folks mentioned earlier in this guide that modded their decks and wrote to tell about it for others to learn, but I'd especially like to thank sonyinsider forums administrator Stephen sfbp for his constant and incredibly helpful communication throughout this project - THANK YOU SO MUCH!

Thanks for reading.

camroncamera

We'll finish this writeup with the following videos of my project:

[sfbp]

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