Information about the Märklin Decoders 60901 and 60902 
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Meanwhile there is some information about the new Märklin Decoder 60901 (with motor) and 60902 (without motor) in the Internet. At this page I want to collect, what information meanwhile arrived me. This information still is not complete, whoever knows something new, is invited to contribute to a completion.
 

 
First I might remind however, that I have examined this information to best knowledge and consciences. I cannot rule out however, that there may be mistakes existing in the sources of my information, or I may have added additional mistakes. Therefore I don't accept any liability for damages, that originate out of the utilization of this information.

 

1. Base technology

The Decoders 60901 and 60902 are a complete new design and based on a new chip, 701.22B. In this chip more functions are available than in the old ones (701.13 or 701.17). The differences are:
This chip is designed for the new (Märklin/Motorola) digital-format, however it also still "understands" the old (Motorola) format, if the additional functions of F1 until F4 are ignored. Both digital-formats are described by A.Scorzoni, the old format also in the German Märklin books

2. Possibilities and connection of the Decoders

In the usual version of the Decoders the functions F0, F1 and F2 are completely implemented. For the utilization of function 3, 3 more parts need to be added, and function 4 is normally used for the internal control of the acceleration and braking. You can also utilize the F4 as an output with addition of some components, however the switching off of the acceleration and braking delay is then no longer possible.

When operating with the conventional transformer (AC), in contrast to the C90 the function F0 (journey-direction-dependent) and F1 are continually on. The functions F2, F3 and F4 are continually off.

The normal connection information was at the beginning not general available, therefore a sketching:

C91 Connection diagram

The maximum ratings of the exits is here also shown:
 
Motor output
max. 800 mA
   
Function output
max. 200 mA
(all 3 together however no more than 400 mA total)
Complete component
max. 1100 mA
   

 

3. The Circuit

The details of the Decoder-board are shown in both following pictures:

C91 Front view
Forefront

C91 Rear view
Rear

The blue coloured components are not included in the standard decoder. Further details are discussed underneath in the section “expansions”.

The same is valid for the now following circuit:
 

C91 Diagram

The values of the components are:
 
  R1
10k
   C1
10uF/16V
  R2
10k
   C2
10uF/16V
  R3
10k
   C3
1uF/50V
  R4
100k
   C4
220nF/50V
  R5
47k
   D1
BYD77D
  R6
47k
   D2
BYD77D
  R7
47k
   D3
BYD77D
  R8
47k
   D4
BYD77D
  R9
3R9
   D5
BZD27C47
  R10
3R9
   T1
i.e. BST 51
  R11
3R3
   T2
i.e. BST 51
  R12
3R3
   T3
i.e. BST 51
  R13
3R3
   T4
i.e. BST 51
  P1
500k
      
  P2
10k
      

 

4. Expansions and options

The functions F3 and F4 can be added. For activation of the function F3, the components R7, R11 and T3 are added and the brown/yellow wire at the corresponding solder pad at the edge of the board. For the function F4 a little more is required. The components R8, R12 and R13 and the Darlington transistor T4 are added. Further, the solder pads at S4 must be bridged. This disables the internal function "Rangiergang (shunting) at F4" and makes F4 available externally. A corresponding brown/white wire is soldered to the output solder pad on the board.

Whoever wants the telex-function that the delta Decoder 66031 has, can do this by adding the same components as for F4, but bridge S3 instead of S4. Thereby this additional function is, same as with the Delta-Decoder, also usable in the conventional AC operation, and the internal function "Rangiergang at F4" remains. The function becomes then activated through several changes of direction.

In the end one more little candy. Viewing closely the circuit will show that the pins 13 and 14 of the 701.22B are not connected to anything. These two pins are used in the ICE or Cargo Sprinters to facilitate switching the pickup shoes. At the switching of the journey-direction a short pulse (about 50 ms) is outputted on the corresponding pin, so one can connect the two coils of a bistable Relay (protection diodes necessary!) from these to pin 20 of IC1 (that is, one side of each coil goes to one of pins 13 and 14, the other side of each coil goes to pin 20).

Many thanks to Norman, who triggered me for this page with his translation
(c) Jürgen Schad & Norman Champion, 03.10.2002