Updated 27 Sep. 2002


Conversions and enhancements



  At this point in time the old Delta(6603) is no longer available.

It has been replaced by the 66031/2.

If the 66031 is your current Delta decoder, only the 80 address option is usable

**!!** The 66032 allready support 80 addresses **!!**



The Delta Decoder is Märklin's cheapest decoder, and the one with the fewest functions.

However this can be changed, with some additional components and a solder iron.

So what can you do yourself, to make the Delta Decoder better.


    Check it out:

  • You can get all 80 addresses
  • You can get the function
  • You can get the four extra functions

  • Get all 80 addresses. (This modification can be performed on all Delta decoders)

    When you use the dip switch Dib Switch you can either set ON or OFF(pretty obvious)

    "ON" matches the odd number on the 6080/6090, and "OFF" matches "--" that is neither

    odd or even numbers are set to ON on the 6080/6090 dip switch.

    In order to chose a digital address look at the digital address table, and find your desired


    On the Delta decoder you have odd numbers and "open", therefore the problem is to get

    the even numbers. What you do is set the switch OFF, and then solder a wire to a reference-

    point, which gives you level for the even numbers. You therefore need to solder the wire from the

    Delta dip switch to eg. the "big" capacitor. Address change

    Say you want to make the setting of dip3 to equal the

    level for an even number, you solder a wire from dip3,

    on the side that faces the board edge, to the capacitor,

    and solder the wire onto the side of the capacitor which

    has a marking (a light or dark line, depending on the color

    of the capacitor).




    If you want to use eg. address 64, the digital setting is:

     Märklin setting   6080/6090 Dip switch setting
      -2   3-   -6   --  set the following: ON : 2, 3, 6   OFF: 1,4,5,7,8

    Dip1 on the Delta equals dip1+2 on the digital. Dip2 equals dip3+4 and so on.

    In digital, you use two switches, to make one bit. It can either be high, low, or "floating"

    (both switches=off).

    Look in this table, to see the possible settings:
     DIP "odd" DIP "even" Result

     Delta equivalent
     on on illegal 

     on  off low 

     off  on high 

    impossible *
     off  off floating 


    * This is the setting that needs the modification. You set the switch to "OFF" and solder

    a wire to the capacitor.

    So, in the case of address 64 you set the Delta switch 1:OFF 2:ON 3:OFF 4:OFF

    You then solder wires from dip1 and dip3 to the capacitor.




    This is how you make address 03   ( ON, OFF+solder+off, ON, ON )

    This is how you make address 63   ( ON, ON, OFF+solder, OFF )


    If you don't want to modify you Delta decoder, you are limited to these addresses.

    So maybe it's worth taking the chance.


    If you want to read more about the digital format, or how Märklins trinary format

    Works, try this excellent page New Märklin Motorola Format by Andrea Scorzoni.

     Get the function. This modification can ONLY be performed on 701.17-based Delta decoders.

    The function equals the button "function" on your Control Unit 6021. This function is already

    present on the 6080 and 6090. You use it to turn on/off the headlights or to drive a Telex or a

    smoke unit. To have this function on your Delta decoder you need to solder a bit, and cut a little

    in your Delta circuit board. How much depend on which model of decoder you have. What you need

    is actually only two 10K(can be smaller) resistors and maybe a 2V7 zenerdiode.

    (maybe also 2 transistors if you have one of the old decoders). Besides adding the function it can

    also remove the annoying flickering you normally se in your train's headlights.


    The Function

    The Function is enabled, by adding the components described in the schematics

    You may have to cut a few leads on the Delta Circuit board, solder the appropriate components,

    and connect your bulbs, Telex or smoke unit, and you have the function.

    BUT - how do you go about making the conversion.

    There are two ways:

    1. You use a sharp knife to cut/break the leads that comes from the 701.17 chip. You then solder the

    resistors where you find it best. The disadvantages with this method is : where should I cut ?

    and what if I regret the conversion ?. (the questions are rhetorical and need no answer)

    2. The second method is the one I personally use. It is a bit more difficult, but a far better solution,

    because you don't have to cut at all, so you can always return to the starting point.

    First of all you need to buy two SMD 10Kohm resistors.(actually any value from 1 - 10 Kohm will do !)

    You then have to raise pin 6 and 7 on the 701.17 chip, from the circuit board. Use the tip of a small

    screwdriver, which you insert between two pins on the chip. You then apply heat (with a soldering iron)

    and gently tweak the pin up, as shown in this drawing.

    Next step are the resistors. Desolder the two resistors, shown on this

    picture.(this is only valid for the decoders where the resistors are placed as shown).

    Now you solder the the two (1-)10k resistors to the board. Here is another tricky task, because the resistors

    should be soldered at angle, and they should be soldered to the plates nearest the board's edge.

    Check the pictures/drawings for details (sorry, the pictures are not totally clear)

    How should you angle the resistors, compared to a normally soldered resistor ?

    How should it look ? Example 1   Example 2

    Then you solder the wires. I use thin lacquer-isolated copper wire. You solder wires from the raised

    pins on chip to the plates where you soldered the resistors - see this example. The "top"-ends of the

    resistors should be soldered together and then connected to the diode right beside the dip-switch.

    The other wires should be soldered to the plates where the resistors are soldered to the board. The wires

    are then to be connected to pin6 and 7 on the 701.17 chip.

    Here are some pictures showing the above descriptions

    The raised chip-pins, with wires soldered

    Overview of the wiring

    Overview of the finished result




    You can only remove the flickering, if your bulb sockets are of the new type with two solder

    pins on the back, or you have the possibility to detach the bulb from the chassis(on old loc's

    the bulb-holder is normally integrated in the chassis, so here it is difficult).

    (Check my tips & Tricks -page on how to retrofit a locomotive with the new type of bulb-sockets)

    You connect the bulbs with one wire to the transistor(the yellow and gray wires) on your Delta

    and the other wire through the zener to motor power.(normally the black wire)   

    Voila ! No more Flicker in your light bulbs.

    It's all described on schematics you can download. If you have the older types, and you cannot

    detach the socket from the chassis, you can still remove flicker, but you must make the modification

    with extra components. Check out the digital enhancement page.

    You don't HAVE to use the Zenerdiodes which you see in the schematics. Their job is to lower the

    voltage to the bulbs, because the Digital voltage is higher than the normal analog voltage. If you

    are satisfied with the bulbs brightness, don't add the zenerdiodes.

    P.S If you are converting a loc which have an electronic circuit to change direction, it is most

    likely that the bulbs are Märklin number 6000xx. These bulbs are LOW VOLTAGE bulbs, and

    will burn VERY brightly, and they may burn out fast. You should change the bulbs to 6100xx.


    The schematics

    The schematics is made by Dr Michael König Who also has an excellent homepage regarding this subject


    Get the four extra functions. This modification can ONLY be performed on                                                                           701.17-based decoders

    It is now possible to enable all the four function you see on your Control Unit (F1-F4), as well

    as the "normal" function, described in a earlier paragraph. You can also avoid flickering, just

    connect your bulbs(possibly through a zenerdiode, to lower the voltage) to motor-power instead

    off chassis(track ground).

    This conversion is not as easy , as the others. First up, you need a few extra components, and

    connect them acording to the schematic shown here to the right.  (Schematic created by Michael könig)

    You use a 4094 shift register and four transistors.Delta Add-on 

    The transistors must be connected to the output of the 4094.

    The transistors handling the light front and back, should be able

    to handle 200mA.The transistors who handle the function output

    should handle approximately. 1A.

    And last, you will also need a 270Kohm resistor.

    Bo braendstrup has made a very small PCB, which uses SMT-

    components. He uses a dual transistor ;NDC7002N for the

    normal functions(the front/back lights). And two ZETEX

    FMMT491A to handle the function output. In this version only

    F1 and F2 are enabled, but it is possible to enable all four functions. But here you are on your own.

    You have to build the add-on yourself, according to the schematic above. This however requires at bit

    more work, than just connecting a premade curcuitboard.

    Here are Bo Braendstrup's PCB layout enlarged :Delta Add-on - Layout

    R1+R2  : 820 Ohm

    Q1+Q3 : FMMT491A

    Q2       : NDC7002N

    IC1     : CMOS 4094


    Actual size is 1,4 cm x 1,4 cm


    The assembly:

    First the hard part. You need to desolder pin 3,4,5,6,7 on the 701.17 chip from the PCB.

    I find the easiest way, is to use a small screwdriver. You place it between two pins eg 2 and 3.

    You then put your solder iron down on pin 3 and at same time use your screwdriver to

    gently tweak pin 3 up from the PCB.

    You then solder wires from the add-on to the pins you desolderd on the Delta chip. Look at the

    schematic to see what pins to connect with each other. Finally you mount the 270Kohm

    resistor between Delta chip pin 5 to track ground (brown wire). It is not totally nessesary to use

    all the 22 Kohm resistors, as shown in the schematic -you can chose not to use them.


    The schematic over the add-on


    You can read more about this subject on Dr. König's homepage and Bo Braendstrup's homepage.

    Bo has a great homepage with allot of modifications to Märklin's Digital system.


    If you have a question about anything I have written, then send me a mail

     Back to main page

    Email :kenneth@pallund.dk