Greetings all,

A problem which has bothered me for a long time is that the Marklin 60760 (entry level) decoder, as well as its derivatives in many of the "Hobby" and starter set locos, exhibit an unpredictable and annoying habit (after a Power interruption), of resuming their speed in an unknown direction when Power is restored. This can be "catastrophic" when running a layout under computer control - the results are invariable a "train-smash" - literally

Investigation has revealed that the design of the decoder is such that the Loco Direction component of the received data "packet" is IGNORED if the first "packet" received after the power outage has a non-zero speed value. I can only assume that this is intentional to cater for legacy AC and MM1 environments.

I'm looking for a solution and am considering some options...

A "keep-alive" capacitor could reduce the impact by remembering the previously set direction, but only for a while, so I'd consider it not to be viable.

A more likely option would be to re-code and re-program the micro-controller on the decoder with a version of software which ALWAYS "obeyed" the direction bit in the received packet (specifically MM2).

So, after all that waffle, my question to all the technical guys out there is, has anyone experimented or done such a modification? I have the equipment to re-program the chip (a Microchip 16F676) and I have my own decoder code, so am about to do some (sacrificing...?) of a decoder. It would of course help if someone has already done this

Thanks in advance,
Norm

Dare I say "Watch this space?". My first effort will be to make a version for MM2 only, no analog support. My code is currently dual protocol (DCC and MM) and fits on a Microchip 16F87x. I'll have to trim off a fair bit of code, but I'm sure it's doable:-)

Thanks for your comments:-) I have used a couple of Control Units - An Intellibox 1, Intellibox II, and IB Com. Also a Marklin 6021 and a Control Unit designed and built for Elektor. I have not gone down the CS2/CS3 route simply because I have too much invested in The Intellibox/LocoNet/and DCC systems. I'd be very interested to hear if the same problem exits with the CS2 or 3 Command Stations, but I suspect it does, because my findings is that it's part of the 60760 design - reasons below:-).

During debugging with the self designed Elektor unit and in discussions with the author, we learned of this "quirk". I suspect the way it's been designed is to handle a transition from an Analog/AC section of track, to a Digital section. In that scenario an Analog locomotive has its direction changed and set by a high voltage pulse, and not by a command as such. (Yes, I know you know all this:-)) but I'm mentioning it as a possible reason to explain why the decoder ignores direction information in data packets which include a non-zero speed value, in order to achieve a smooth transition from the Analog to the Digital section. We have concluded that even though the Control Unit sends data to the loco, including direction information, it's possible for the 60760 to resume in its DEFAULT direction, and NOT what the Control Unit is sending.

Clean track is indeed an absolute must to minimise the issue, but short circuits coming from derailments, or simply cutting and restoring power are where the problem is most evident.

A question you could answer for me is what happens with a CS2 or CS3 when you have a short circuit and press the "resume" after correcting the shut-down? Do all locos have their speeds set to zero and then have to be restarted?

Accidental double post.