DCC Using Zimo Swiss Mapping to control Heljan Rear Lights

Discussion in 'Techniques' started by TheSnapper, 5 January 2015.

  1. TheSnapper

    TheSnapper Western Thunderer

    About 6 years ago I installed a Loksound XL v3.5 in a Heljan Hymek, and posted the details on the (now defunct) MIG0 Forum. This was copied over to this forum - see Posts #1 & #2 here.

    It worked OK, and with subsequent amendments to the wiring, and suitable CV changes, I was able to switch the red lights independently.

    I have to admit that despite the wiring mods to the PCB being sanctioned by Heljan, they are a bit messy & look” unprofessional”. Nevertheless, it worked, so I did the same modifications for my Heljan Class47, which has exactly the same board. (The newer Heljan locos have a different PCB; I’m not sure with which model they changed).

    Incidentally, the wheel profile also has changed with the newer models. Both my ’47 wheels & this Hymek’s wheels have been superbly re-profiled by Colin Dowling (eastsidepilot of this parish). Also the motors don’t seem to be so “power-hungry”. For instance, I have successfully used a Zimo645 in a Class 31 and a Class20. However, I have since replaced the decoder in the ’31 with a ZimoMX695KV, and I have removed one of the motors and the flywheel from the ’20…..but that’s another story

    Anyway, back to the topic: The ’47 remains in pieces – I have a habit of reducing Heljan models to kit-form! .My excuse is that it’s awaiting the application of a full detailing kit from MMP. Also, since I bought it, I have gone over completely to Zimo decoders for various reasons. I think they have better motor control, a better manual, and are better value. Not to mention, some great sound projects available from Digitrains & especiallyPaul Chetter (eg the LNER A4/A3 is superb…). No connection, just a satisfied customer.

    Nowadays, I’m not really bothered about working lights or fans, so I tend to disconnect them completely (isn’t the Heljan fan awful – so NOISY). However, I was asked by a friend to install sound into his Hymek, and he asked if I could replicate my installation. (BTW, I no longer have my own Hymek)

    I would have liked to try the method as described beneath mine in Post #3 here, but couldn’t source the Heljan-style connectors. I even contacted Heljan, hoping they would sell or give me a small quantity, but they could only offer to sell me 10,0000! So I took the lazy way out and decided to use the already-prepared Heljan PCB from my ’47, together with my favoured Zimo MX695KV instead of a Loksound XL. I say “lazy way out”, because it meant that I wouldn’t need to do any rewiring or fitting series resistors for the LED’s!

    To cut a long story short, I am indebted to Paul Chetter, via RMWeb, for his help in achieving independent Red Light switching using Swiss Mapping on the ZimoMX695. To be quite honest, it is a section of the Zimo manual I have ignored in the past, as I wrongly assumed it applies only to Swiss loco lighting! How wrong I was! It has enormous potential being so simple to configure, compared with the struggle I had trying to do the same for another installation using the Loksound XLv.4

    Paul said:

    Decide which F Key you wish to operate the red LEDs. Since this action will be infrequent in comparison to playing various sounds etc, I suggest you use a high F key which does not already have a sound or function assigned, say F22. The actual one used is irrelevant, but I'll use this as an illustration.

    So, if you know which Function Outputs are connected, and which F key you wish to use:

    CV430 = X (where X is the number of the F key, in this case F22, so CV430 = 22)
    CV432 = Y (where Y is the number of the Function Output you wish to operate in the forward direction, in this case FO1, so CV432 = 1)
    CV434 = Z (where Z is the number of the Function Output you wish to operate in the reverse direction, in this case FO2, so CV434 = 2)

    PS, to add 'softstart' to all the lights, add 52 to the values in CVs 125, 126, 127 and 128.

    I coupled up the modified Heljan PCB to the Zimo695, according to this diagram:


    Then I configured the CV’s as he suggested. I even got the fan working on FO23 using “Swiss Mapping Group 2”, and tamed the speed (& noise) satisfactorily with a combination of on-board potentiometer adjustment & Function Output “dimming” (CV60).

    And it all works.. I rate Swiss Mapping as "My Discovery of 2014"!


  2. Dikitriki

    Dikitriki Flying Squad

    I'm very glad you're a member of the Heyside Group Tim, because that is so far over my head.......:)

    3 LINK and Dan Randall like this.
  3. Scale7JB

    Scale7JB Western Thunderer

    I still find stay alive capacitors to be a bit sophisticated...!

    3 LINK likes this.
  4. Pugsley

    Pugsley Western Thunderer

    Thanks for putting this up - I hadn't read that part of the instruction manual and it is very useful. I configured the lights on my 37 using the advanced configuration with CV 61 set to a value of 98, which works well, but means that I need to reduce the volume on some of the sound effects (that I'm probably not going to use anyway).

    However, this other method means that I can use the higher function for the lights, leaving the sounds untouched.
  5. Dog Star

    Dog Star Western Thunderer


    I have done a search for Zimo and Swiss, the results need some clarification and I hope that you can explain.

    What does Swiss Mapping offer?

    Why is Swiss Mapping an improvement over what has gone before?

    thanks, Graham
  6. TheSnapper

    TheSnapper Western Thunderer

    Hi Graham

    IMHO, the main advantage of Swiss Mapping is that it is so simple to configure, compared with the struggles I have had in the past trying to do the same using other decoders. After setting-up the first one, you hardly need to refer to the manual, but see p28 of the manual here:


    With “traditional” function mapping, choosing which Function Key to use has always been a dilemma for me. Using Swiss Mapping, you can allocate a Key which does not already have a sound or function assigned (see Pugsley’s post, above). Alternatively, you could deliberately use a key that does have a corresponding sound eg switching-on a fan.

    The Zimo MX695KV has 12 Function outputs (13 if you include F0-lights), and using Swiss Mapping groups, you can assign each one to a Function Key of your choice, in seconds! Having said that, it would be one hell of a loco that required 13 controlled functions!

    Finally its worth noting that each Function Output can easily be assigned to work in either direction, or both.


    Dog Star likes this.
  7. Dale Heys

    Dale Heys New Member

    Tim, this was a series of excellent posts about how to install DCC in older Heljan O Scale Diesels, I am following the posts to DCC a second hand Hymek I have with a Loksound XL 4.0.

    Like you I don't like the idea of "hacking" the original PCB and your design for the replacement "board" is good, so am replicating it!

    Reason for my post, you stated you couldn't source the Heljan connector sockets any more, you are quite correct they are no longer produced by Molex (the manufacturer) however; after contacting Molex they pointed me to "Mouser Ltd." (Mouser Electronics United Kingdom - Electronic Components Distributor) in the UK who still have in excess of 4,500 of them (at the time of writing), just use the original Mouser product code (538-89400-0220) or search on the Molex product code (89400-0220) to find them once on their site.

    I have just ordered 100 myself (to have a few spares if needed) for £7.50 + P&P so will be making the board this weekend!

  8. victorianman

    victorianman Western Thunderer

    Can't comment on the mapping etc., but I, too am switching to Zimo decoders , the no-frills budget ones (!), having found the quality of motor control out of this world. They acknowledge the use of core;ess motors, too, which I find reassuring. I also make life simpler by using JMRI and a SPROG for a good, basic set-up, and maintain that if I can use these, anyone can.
  9. parky

    parky Western Thunderer

    I have only used Zimo when I have put sound in my locos. The best has to be the Heljan Class 40 as I set up the Swiss mapping as it means we can double head locos at the club and I can selectively turn of the inappropriate lights. The directional function still works but you can choose t either head or tail light to be off

    It took a bit of trial and error to set it up as Heljan use red and black wires without any real logicAnother advantage over my friends Loksound Class 40 is I have function keys to increase the volume for clubroom use or reduce for home use. It makes it so flexible

    Another vote for Paul Chettar's sound projects and if I get one of the new Class 47's it will have to get another Zimo 6xx series chip
    Last edited: 11 January 2019
  10. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    ESU also acknowledge use for coreless motors and like Zimo they also have superb motor control.
  11. Steph Dale

    Steph Dale Western Thunderer

    ESU do that too. Usually on F8. In terms of performance there's little more than a hair's breadth between the feature set of ESU and Zimo. It may just be that the provider of the sound profile has turned it off, although for the life of me I can't think why...

    Arguably the command programming of the ESU decoders makes them more adaptable, although I've not obviously seen that feature used by any of the providers of UK sounds.

    Last edited: 11 January 2019
  12. Blueeighties

    Blueeighties Western Thunderer

    I know this thread was started a long time ago but I'm just curious....why alter the original Heljan pcb or manufacture a new one....the pcb is always binned and everything wired directly to the chip? Or at least that's how I do my installs. A few of the original big Heljans such as the 37 and 47s used filament bulbs so need resistors wiring in, but pretty much everything else uses leds with appropriate resistors already installed on the lighting board pcb.
  13. Ressaldar

    Ressaldar Western Thunderer

    Hi Lee,

    As ‘supplied’ the tail (red lights) always come on, regardless of whether running light or hauling a train. Using ‘Swiss mapping’ allows you to switch the lights off when hauling its train and numerous other applications as well.


  14. Richard Burston

    Richard Burston New Member

    Dale Did you get your Molex bits yet as I am looking for what I believe is the mating part, the trailing socket as the part no you are showing is the bit that mounts on the board.I have a sound fitted Hymek but it seems someone removed the front and rear lights.