Dapol 08

Discussion in 'Talk' started by Ressaldar, 21 March 2016.

  1. Steph Dale

    Steph Dale Western Thunderer

    Jim, Graham,
    The QSI white paper on model loco acoustics may help a little, although sadly no longer on their 'site...:


    Attached Files:

  2. FiftyFourA

    FiftyFourA Western Thunderer

    I just realied that using the 'upload a file' thingy would work for pdfs as well as piccies :confused:, so here is the JLTRT 08 file Laurie sent me.


    Attached Files:

  3. TheSnapper

    TheSnapper Western Thunderer

    In case anyone is interested, Paul Chetter can supply a 21-pin Zimo644D decoder especially for the Dapol 08, with fully controllable lights and some other unique features.

    Contact Paul for more details at soundsloco@btinternet.com

    Usual disclaimer: I have no commercial connection, just a happy customer!


  4. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    My understanding is that MTC21 is the connector which has NMRA approval and NEM recognition. Therefore by default all 21 pin decoders are MTC compliant and should work provided the decoder has sufficient functions viz.

    Having checked the latest respective manuals. The ESU Loksound V4 pins 2, 3 (wheel sensors) and 17 (motor 3) have no connection whereas they do on the Zimo Mx644D for functions 5 and 6. This unfortunately means checking the decoder specifications before selecting.

    I also checked the NEM 2011 Electrical Interface Recommendation and NMRA recommended practices (RP-9 1.1) just to be certain.

    Loksound V4.0

    Zimo MX644D. Note this does not have a blank index pin but a ground instead. Take care when installing.
  5. JimG

    JimG Western Thunderer


    That's a good paper that goes into a lot more detail than my efforts above.

  6. richard carr

    richard carr Western Thunderer

    Mine hasn't been converted to S7 yet I just ran it on some plain track.

    Converting this one is a job for Col !
    eastsidepilot likes this.
  7. eastsidepilot

    eastsidepilot Western Thunderer

    If they're anything like the Bachmann then it'll be interesting ! :D

  8. richard carr

    richard carr Western Thunderer

    Hopefully Col it's not.

    Are you going over to John's in the near future ?

  9. eastsidepilot

    eastsidepilot Western Thunderer

    PM sent mate.

  10. SoundsLoco

    SoundsLoco Member

    Hi Dave,

    You are right to highlight the differences and especially that potential purchasers should check the specifications carefully, but some of what you said needs slight modification.

    21MTC is a Decoder/ Loco PCB specification originally produced by ESU for Maerklin (Maerklin - Trix Connector). The specification requires that all function outputs from AUX 3 and above should be Logic Level only. All ESU 21 pin decoders and some other brands (Lenz, TCS?) follow this spec. Logic Level means that there is always a voltage present at AUX 3 and above.

    The problem is that although the paperwork with the Dapol 08 carries the 21MTC logo, the model does not actually comply with the MTC part.

    That is, the Loco PCB is designed to work with Aux3 as a 'normal' or 'open collector' function output. Open collector outputs have no voltage just a switching function. Power is supplied by the common positive. So you can see that the PCB is 'expecting' to see 0v at the AUX 3 pinout.

    As 21MTC compliant decoders always have a (Low) voltage, LEDs connected to this are permanently powered so long as the loco is powered.

    The ZIMO MX644D is a 21 pin decoder, so it fits the same physical connector, but all function outputs up to No 8 are open collector types. Thus, there is no voltage to the LEDs until the AUX is switched 'on'. This makes anything connected to Aux3 controllable, on/off.

    This is the decoder which Dapol will be supplying with the 'official' sound project. (Details here:

    A further complication which can pply to ant 21 pin decoder, MTC or not, is there needs to be sufficient function outputs available for the number of separately controllable circuits on the model. This often does not cause a problem since many R-T-R models do not use many function outputs.

    Dapol have designed this model with top marker lights, directionally switched, that's 2 function outputs. There is a cab light on Aux 1, a pair of front shunting lamps on Aux 2 and a pair of shunting lamps at the rear on Aux 3. If you total that up, it is 5 function outputs in all.

    If the decoder does not have a minimum of 5, 'normal' (open collector) outputs, then some features will not work. In this case, Aux3, the rear shunting lamps.

    So, 21 pin 4 function decoders of any type will leave the rear lamps permanently unlit, and 21MTC decoders with 5 or more function outputs will leave the rrear lamps permanently illuminated.

    Physical rewiring of the model's electrics will be needed to overcome this hardware incompatibility.

    This interface was declared 'obsolecent' in around 2009 and manufacturers were supposed to stop designing new models with it as their DCC interface.

    There are two 'new' plug in interface standards which by and large stop this sort of misunderstanding by closely defining not only the electrical connections but the physical sizes of the decoders and the space that manufactureres must leave in their models to accomodate the decoders.

    NexT18 is intended for N gauge and small 00 models. Common in Europe, now adopted as standard by Bachmann for Farish N gauge and some smaller Branchline models.

    Plux22 (and 16, 12 and 8,I think). Theses are physically similar to 21 pin decoders, but the pins are on the decoders, not the connectors so they are not interchangeable. This standard has been adopted by Sutton's Locomotive Workshop and Little Loco Company to be able to exploit all the decoders' features.

    Finally, the ZIMO MX644D decoder itself does have any pins in common wit all other such decoders. The male connector (with the pins) will be found on the loco PCB. That will normally have a missing or 'index pin'.

    The diagram you reproduced from the ZIMO small decoder manual does show the connection as 'Ground' but there is no actual metal in its connector for a pin to make contact with and the 'hole' is blanked off to resist the entry of a pin if somehow incorrectly orientated; it would be possibe to solder directly onto the decoder to use this ground connection if it were needed.

    Hope this clarifies the MTC issue which can be a rather confusing.

    Kind regards,

  11. SoundsLoco

    SoundsLoco Member

    A short video might give some idea of the sounds...

    Here's a link to the Dapol 08 with my ProtoDrive sound project:

    and similar project in a Bachmann 08

    Kind regards,

    Yorkshire Dave likes this.
  12. InvernessTMD

    InvernessTMD Western Thunderer

    Sounds like a strip out and rewire is in order then...
  13. Temeraire

    Temeraire Western Thunderer

    Or use a Zimo decoder...
  14. richard_t

    richard_t Active Member

    Unless you pre-purchased a ESU LokSound on the basis that the model was 21MTC compatible ... "like wot I did"
  15. Temeraire

    Temeraire Western Thunderer

    Well yes. That would be a bit awkward I grant you!

    An ESU decoder would be my preferred option too. I do think Dapol have dropped a bit of a clanger here. Surely if you publish a spec that includes
    being 21MTC compatible you need to make damn sure it actually is. Kind of defeats the object of decoder standards otherwise.
  16. richard carr

    richard carr Western Thunderer

    Your ESU decoder is MTC compatible, it just doesn't have enough functions for you to control all the lights.

    Dapol should have said MTC compatible plus a minimum of 6 powered functions.

  17. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    Quite agree.

    Out of curiosity does the DCC label on the Dapol box carry the MTC21 logo?
  18. SoundsLoco

    SoundsLoco Member

    No. The only place it appears in on the 'Owners Guide' - I use the term loosly as that's what Dapol call the single sided A4 sheet, and even then it is so oddly placed it's easy to miss.

  19. Ressaldar

    Ressaldar Western Thunderer

    Title edited to be more in line with the generality of the topic.


  20. SoundsLoco

    SoundsLoco Member


    That's the problem, the ESU decoder is 21MTC compatible, but the model is not. The model expects to 'see' an 'Open Collector' function output on AUX3, which the ZIMO, TCS and others which follow the NMRA standards will provide.

    ESU 21 pin decoders have Logic Level on Aux 3, and the'wrong polarity'. The pin is always live, therefore the rear lamps on this model cannot be switched off.

    The 21 MTC specs (NEM660) require 'Logic Level' function outputs on Aux3 and above. In other words, there is no such thing as a 21MTC decoder which has 6 'powered', 'full power', 'normal' or more correctly 'open collector' function outputs.

    The issue arises because the term 21MTC is used incorrectly by some to mean 'any 21 pin decoder'.

    It's only because Dapol have used a function output above AUX 2 that this disparity has come to wider attention.

    The sooner we move to the PluX interface the better, as it removes this problem altogether.

    Kind regards,