Adding a Digital out to MDS-JE330

Have you ever wondered, why cheap MD-Decks don't have digital out although they operate on digital audio? The answer is: They do have a digital out. This document ist about how to add a Coax or toslink connector to the MDS-JE330 form Sony.It may work also with other MDS-Models, but maybe you have to use other jumper wires to connect.

Disclaimer: I tried this with my MDS-JE330 and it worked. That doesn't mean it will work with yours. You may even damage your device. Anyhow, your warranty will be void!

What you need

Soldering iron with a thin tip
small experimental PCB
100nf Capacitor
Shielded wire
4.7 Ohm resistor
8.2 k resistor
toslink transmitter TOTX173 (in Switzerland at Pusterla(Zürich) or Distrelec)
toslink transmitter GP1F32T
150 Ohm resistor
330 Ohm resistor
Cinch connector female

Finding the connections

When you open the case you'll see a big brownish PCB with the power supply on it. You have to find the following points to connect your wires to (according to the figure bellow):

Jumper wire JW405
Jumper wire JW473
Capacitor C416 (here you need the + pin)

I suggest that you take a shielded wire at least for the S/P DIF signal (JW405). Take a soldering iron with a thin tip and sold wires to the pins as follows:

JW405 (TTL S/P DIF Signal) to inner conductor of shielded cable (thereafter called wire 1)
JW473 (GND) to outer conductor (shield)
C416 (+5v) to other inner conductor or to another (unshielded wire, wire 2)

You don't need wire 2 for the coax output!

The "converter"

Now we have to convert the 5v TTL level S/P DIF signal either to 0.5v coax or to light pulses using a toslink transmitter. Look at these schematic diagrams


Schematic diagram for toslink output

Schematic diagram for coax output.

I built these circuits on a small experimental PCB. I haven't tested running both circuits parallel, but that will probably work as well.

Here's an alternative, easier circuit using Sharp's GP1F32T (I couldn't try these yet. Please tell me if it worked with your deck)

What if I have another low-end Sony Minidisc Deck?

Larry Battraw informed me about S/P DIF out at his JE320. Here you have to connect wire 1 (S/P DIF) to JW17 (instead ofJW405) and the shield (GND) to JW187 (instead ofJW475). He couldn't tell about Vcc but that one should be easy to find using a DMM (see tips below).

If you want to find the right connections on your non-320 non-330 Minidisc recorder, the following suggestions could be helpful:


Well, that one is easy. Just look for the big, broad copper traces near the output/input section on the PCB. Take a DMM or a continuity tester to check. Or take the GND of the analogue audio connectors.

Vcc (5v)

You have to be sure that your 5v supply runs enough current for the toslink transmitter to drive. Search near broad coper traces and big capacitors using a DMM.


That's the hardest one. Turn on your deck (but don't start playback) and use a oscilloscope (use a high-frequency probe!) to search for a steady square wave signal with aprox. 350 ns per bit (raise to fall) or 700 ns per period (raise to raise) respectively as shown below. The picture should become unstable when playback started, showing that the data transmitted isn't 000000... anymore (which is represented in biphase mark by high-low-high-low-high-low...).