The D7 7-pin connector

D7 digital i/o
Heiko Purnhagen (purnhage@tnt.uni-hannover.de) Tue, 27 Jun 95

Date: Tue, 27 Jun 95 17:18:01 +0200
From: purnhage (Heiko Purnhagen)
To: dat-heads@virginia.edu
Subject: D7 digital i/o

***** Version 2   Heiko Purnhagen   29-jun-95        *****
***** capacitor added in SPDIF output circuit        *****
***** additional notes concerning SPDIF transformers *****

Hello DAT-folks!

Somehow I managed to find shop here in Germany having one "RK-DA10"
cable (digital coax input for D7) in stock for 99.- DM ... and spent
that money.  Being curious about what's inside the 7-pin plugs
housing, I completely diassembled it. With the help of several
DAT-heads postings concerning this 7-pin connector (see list below), I
more or less understood what's going on in this small box and would
like to summarise this stuff here:


The D7 7-pin connector
======================

 PIN    FUNCTION

  1     transmit (SPDIF out, CMOS levels provided)
  2     +4V/+5V regulated
  3     dig/ana (connect to ground for "dig in")
  4     POWTRG (unregulated power ???)
  5     receive (SPDIF in, CMOS levels required)
  6     ground
  7     "sircs" (serial remote controll input ???)
shield  ground

NOTES:
- I suppose the D3 to have the same pinout on its 7-pin connector.
- While runnig from the mains (without batteries), I measured +4.2V at
  pin 2 and +5.2V at pin 4.
- Pin 1 (tx) has full CMOS level (0V / 4.2V).
- Both inputs (pin 5 and pin 7) are internally pulled down to 0V.
  Both inputs have a input resistance above 20 kOhm.
- There is a kind of random digital pulse pattern (min. pulse length 10 ms)
  on pin 3 (with a source resistance of about 500 Ohm).
  You have to connect pin 3 to ground with a resistor of less than
  50 kOhm to get "dig in" instead of "ana in".

??? Any idea what the pulse pattern is good for ???

  
PINOUT (as seen from outside the D7) 

   1 2 3 4
 +---------+
 | o o o o |
 | o o o  /
 +--------
   5 6 7
  
NOTES:
In this pinout diagram, pins 5 and 7 are swaped (compared to all
previous postings) !!!
I have no original source (SONY-manual) available, but I expect
the pin <-> functions lists in the different postings to be more
reliable than the pinout diagramms and thus "decided" to swap the
pin numbers on the pinout.
The correspondence between pinout and function given here I checked
by measurement.


But now for the "RK-DA10"
=========================

The first PCB in the 7-pin plugs housing carries the "dig/ana" switch.
It connects pin 3 to the 7-pin connectors shield if set to
"digital". Otherwise, pin 3 is open. The other PCB contains 3 SMD
resistors, 2 SMD capacitors and 2 SMD gates (labeled "E6" and "E5").
I'm quite shure that these are an inverter and an inverting
Schmitt-trigger similar to 74HCxx gates. This circuit amplifies the
0.5Vpp SPDIF signal on the coax input (which is terminated by a 75 Ohm
resistor) to CMOS level and sends it to pin 5. The circuit is powered
by pin 6 (ground) and pin 2 (+4V/+5V). The coax input shield is
connected to ground (and so there is no input transformer).

I'm afraid that I shouldn't give the detailed scematic of this circuit
here, but there are some similarities to my DIY interface described
below. (There are not so many different ways to design such circuits.)
If you have further questions, you can also e-mail me directly.

If you want to disassemble the plug yourself, first take off the
smaller part of the plastic housing (with "digital / analog" printed
on). Then you can push off the other part "over" the shield of the
7-pin connector. For further disassembling, heat up your soldering
iron ...


Interesting postings on DAT-Heads concerning the D7 7-pin connector
===================================================================

DAT-Heads Digest #770, Volume #1                 Fri, 14 Jan 94 15:12:17 EST
From: Bryan Levin 
Subject: re: secrets of the d3 ;-)

DAT-Heads Digest #847, Volume #1                 Sun, 27 Mar 94 16:12:13 EST
From: Bryan Levin 
Subject: Re: Digital cable to connect two TCD-D7s?

DAT-Heads Digest #129, Volume #2                 Wed, 14 Dec 94 16:12:15 EST
From: Jim Ferr 
Subject: Re: Sony strikes (out) again...

DAT-Heads Digest #300, Volume #2                 Mon, 15 May 95 10:12:06 EDT
From: phopely@eniac.seas.upenn.edu
Subject: d7 cables revealed, help grovel #2

You can find these postings (including the one you are reading) also on
http://www.fet.uni-hannover.de/purnhage/dat/d7connector


Digital Coax Input And Output for the D7 (DIY with standard components)
=======================================================================

After diassembeling the "RK-DA10", I soldered thin wires to all the 7
pins, made a small hole in the plastic housing, reassembled the cable
and soldered the other ends of the wires to a more common connector -
thus having them available for further experiments.

But I also managed to build my own 7-pin plug: I drilled 7 holes (0.5
mm) in a small piece of plastic (3 mm thick), put a short wire in each
hole and fixed them by soldering them to a small PCB. Then I cut the
wires down to the required length and shaped theirs tips. The shield
(not necessary - but prevents the wires from being bend) I made out of
some thin copper plate. OK - my connector doesn't look as nice as the
original one - but works quite reliable ... and is cheap.

The main task of an D7 <-> coax interface is to convert the level of
the SPDIF signal from CMOS (on the D7) to 0.5Vpp 75Ohm coax and
back. This can be done using a 74HC04 (hex inverter - it has to be HC)
- although using real RX/TX ICs for 75Ohm (like
phopely@eniac.seas.upenn.edu or hanssen@netcom.com do) would be more
professional. Here is the scematic of the circuit I build to have
digital coax i/o for my D7:


          74HC04

    +-------__-------+
 1 -| A in      Vcc  |- 14
 2 -| A out    F in  |- 13
 3 -| B in     F out |- 12
 4 -| B out    E in  |- 11
 5 -| C in     E out |- 10
 6 -| C out    D in  |-  9
 7 -|  GND     D out |-  8
    +----------------+


                         +--------+
                         |        <
         +---+    0.1 uF |  |\    > 10 kOhm  |\
 SPDIF   |   |       ||  |  | \   <          | \
 coax    | o-----+---||--+--+  o--+----------+  o---------  # 5  RX
 input   |   |   |   ||     | /              | /
         +-+-+   <          |/               |/
           |     > 75 Ohm
           |     <
           |     |
           +-----+----------------------------------------  # 6  GND

                                 /|
                                / |
                            +--o  +--+
                            |   \ |  |
                            |    \|  |
                            |        |
                    22 nF   |    /|  |    /|
                      ||    |   / |  |   / | 
                 +----||----+--o  +--+--o  +--------------  # 1  TX
                 |    ||    |   \ |  |   \ |
                 <          |    \|  |    \|
                 > 330 Ohm  |        |
         +---+   <          |    /|  |
 SPDIF   |   |   |          |   / |  |
 coax    | o-----+          +--o  +--+
 output  |   |   |              \ |
         +-+-+   <               \|
           |     > 100 Ohm
           |     <
           |     |
           +-----+----------------------------------------  # 6  GND


                      to Vcc ---+-------------------------  # 2  +4V/+5V
                                |
                                |                +--------  # 3  ana/dig
                               ---               o
                        0.1 uF ---     digital    /  analog
                                |                o
                                |                |
                      to GND ---+----------------+--------  # 6  GND


You can also add transformers to the SPDIF output and/or input if
isulation is required. But such transformers (like PE65612) are not
really standard components (I didn't yet manage to get them) ... and
at least in small comsumer setups things will work well without. (The
SONY 57ES has a transformer only on the output, not on the input - and
the RK-DA10 also has no transformer.)
 
All usual disclaimers apply - you have to build and operate such a
circuit at your own risc!

I hope that this information is of interest for you. Any comments
are welcome.

BTW: Has anybody yet managed to find out how to use the "sircs" input???
     If I manage find the required data format, another posting will
     follow ;-)


     Heiko


------------------------------------------------------------------------------
Dipl.-Ing. Heiko Purnhagen   Isernhagener Str. 51   D-30163 Hannover   Germany
e-mail: purnhage@tnt.uni-hannover.de                     phone: +49 511 624449
WWW:    http://www.fet.uni-hannover.de/purnhage/

                      "Theatre is life, film is art, television is furniture."