Page 40 H0 Sound Decoder MX640
Connection and control
of the external power module MXSPEIK:
A complete
power module (MXSPEIK),
which includes above circuitry with extended possibilities,
will be available from ZIMO in the course of 2008!
MORE INFORMATION TO FOLLOW
Connecting speaker, cam sensor:
In order to operate the MX640 as a sound decoder, the following items must/may be connected:
- mandatory –
SPEAKER –
Any 8-ohm speaker or two 4 Ohm speakers connected in series can be
used. Speaker with higher impedance are also allowed but will result in reduced volume.
An additional tweeter (also 8 ohms or higher) can be connected, if desired; the connection should be
made via a bipolar capacitor (10 uF bipolar for 2 kHz frequency).
Speaker installation – TO BE ADDED LATER
-
optional –
CAM SENSOR –
Normally, ZIMO decoders are programmed for the “virtual cam sen-
sor”, which can be fine-tuned with CV #267. If a real cam sensor is to be used, the settings of CV
#267 must be changed to 0 or 1 depending whether each pulse or every second pulse should trigger
a chuff beat. See chapter 6!
Mechanical contacts, Reed switches, optical switches and Hall Effect switches are suitable as cam
sensors.
9.
MX640C for C-Sinus / SoftDrive-Sinus
The MX640C can be switched to a
matching output configuration
required for the control of the
C-Sinus
boards
found in many Märklin and Trix locomotives with
C-Sinus motors
, provided the locomotive
comes with a 21-pin interface. The decoder also
supplies
the necessary
5V
the C-Sinus board needs to
operate (which “normal” decoders are not capable of!).
The MX640C is plugged into the pins of the loco board with the top side of the decoder pointing up,
whereby the pins are being pushed through the decoder board in order to make contact with the decoder
socket. The position is given by the loco board and is also keyed by the missing pin 11 (on the loco board)
and missing hole in the same location on the decoder board.
The picture below shows a sample layout; the loco board may however vary from case to case.
L o c o b o a r d w ith 2 1 - p in in te r fa c e a n d M X 6 4 D p lu g g e d in F la t r ib b o n c a b le to C - S in u s - M o to r
The switch-over to the C-Sinus control takes place with
CV #145,
see CV table!
An MX640C equipped C-Sinus locomotive can be operated in the
NMRA-DCC-data format
as well as the
MOTOROLA protocol
but not in analog mode (DC)!
No motor regulation, known as BEMF, takes place when the decoder operates in the C-Sinus mode, since
the motor tries to keep the target speed precisely in all situations. The relevant configuration variables,
among them CV #9, #56 and #58, are without effect!
The
MX640C
is a special development for locomotives with
SoftDrive-Sinus
and some locomo-
tives with
C-Sinus motor
.
It differs from normal MX640’s in that the function outputs FO3 and FO4 (=
AUX3, AUX4 according to NMRA interface specifications) are designed as logic level outputs and are ca-
pable of supplying the 5V required for powering up the Softdrive loco board (also required by some C-Sinus
boards).
CAUTION:
Unfortunately, Märklin/Trix has played a “dirty trick” (although probably not on purpose): Beginning with a
specific model or past a certain date, the protective resistors on the loco board input have been omitted, or
more precisely, instead of the 100kO resistors useless 0 Ohm resistors are being installed. As a result, a
high voltage from the MX640C reaches the loco board that will not only destroy the board but can
also
damage the decoder; unless the decoder has been set first to the C-Sinus (Softdrive-Sinus) mode with CV
#145.
But even if CV #145 is set properly, there is no guarantee that the loco board will survive (even
though there is no visible problem)!
Background information: Although the 21-pin interface in Märklin and Trix locomotives is virtually identical
to the standardized NMRA-DCC 21-pin interface, Märklin keeps modifying it whenever the need arises
(several versions, misapplication of function outputs for motor activation and now the mentioned electrical
