Page 42 H0 Sound Decoder MX640
10.
The MX640 and competitor systems
All Zimo decoders comply with NMRA standards and recommended practices and can be used on
layouts with other brands of NMRA compliant systems.
What most systems of other manufacturers have in common, in contrast to ZIMO systems, is that
track power is not stabilized or only partly stabilized and often relatively weak (in regards to voltage
but also amperage). This can lead to uneven speeds and/or limited top speed because Zimo decod-
ers are of course programmed by default to operate on stabilized and regulated track power of up to
24V from a Zimo command station.
If such problems arise or as preventive measure, it is recommended to:
- change
CV #57
(reference voltage) from ”0” (where regulation is based on track voltage) to a fixed
voltage. For example: “140” for a DCC system with a typical track voltage of 16 - 18V. In this case
14V will be used as reference, which leaves a certain safety margin during voltage drops.
MX640 with Lenz “DIGITAL plus” from software version 2.0
This system uses 28 speed steps beginning with version 2.0 and 128 steps with version 3.0 and up.
It also programs in direct mode according to NMRA DCC standards and is therefore fully compatible
with Zimo decoders.
All Zimo decoders are set to 28 speed steps by default. Make sure the system is also set to 28 steps
for the decoder address in question. Incompatibility will be the result if the speed steps between de-
coder and system do not agree with each other; which is most often noticed by non working head-
lights. It would only make sense to switch the system from 14 steps to 28 or 128 speed steps rather
then setting the decoder back to 14 steps, which would result in unnecessary poor drivability.
All configuration variables are accessible; see the manual for the cab in question. The address is lo-
cated in the registry’s position #1.
The configuration variables #49 to #54 will have no effect, since the signal controlled speed influ-
ence is only supported by a Zimo system.
MX640 with ROCO Lokmouse-2
Although the Lokmaus-2 allows CV programming, its display is limited to two digits only and there-
fore limits the number of CV’s and their values to 99.
Zimo decoders offer a special pseudo-programming feature with CV #7 (that normally stores the
software version number) to allow unrestricted programming. It is called pseudo-programming be-
cause the permanently stored value in CV #7 cannot be overwritten but rather holds a temporary
value that allows the Lokmouse2 to be used for expanded programming capabilities (see CV table);
the engine must not be running during the programming procedure!
Example:
To enter a value of 160 (which is not possible with a Lokmouse-2 because value is >99) to CV #5
(max. speed) proceed as follows:
First program CV #7 to 1, followed immediately by setting CV #5 to 60. No power interruptions be-
tween those steps are allowed.
Explanation: The value 1 in CV #7 actually 01 (tens digit=0 and ones digit=1) causes the decoder to
add 100 to the CV
value
that will be entered in the next programming step. Therefore, a value of 60
entered to CV #5 with the Lokmouse2 is stored as 160!
Example:
To program CV #122 (exponential deceleration), for example, with a value of 25 do the following:
Again, go to CV #7 and enter a value of 10, then go to CV #22 and enter a value of 25.
Explanation: CV #7 = 10. The 1 in the tens digit causes the decoder to add 100 to the CV
address
in the following programming step. As a result, CV #122 will be programmed instead of CV #22!
MX640
with DIGITRAX Chief
No problems expected with this system!
The Digitrax system usually operates at 28 or 128 speed steps. If for some reason the headlights
don’t work, confirm that indeed the system and the decoder are set to the same number of speed
steps and if necessary, change the speed steps at your cab to 28 or 128 steps.
There have been some malfunctions in the past during system boot up. For example: locomotives
would not start unless the power to the decoder was interrupted briefly (by tipping the locomotive off
one rail). It is not quite clear whether the causes have ever been fully identified and eliminated; it
may also depend on the command station model (year of manufacture) and the software version in
the Digitrax command station.
