Enable F4 function (delay switch) for the Cargo Sprinter 37090 
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Recently I have bought the Märklin Cargo Sprinter. After some "standard" tests I found that the decoder 60902 must be working inside. But it did not react on the F4 function which normally enables/disables the acceleration/deceleration delay (as long as this function is not used for other purposes). So it was not too hard to decide: do it (using the soldering iron). But before you start (warming up your iron) please note :

Please note what Märklin is announcing to this theme: If you do any changes to the electronic equipment of your locomotive by your own, any warranty is void, so it´s at your own risk. And you cannot get any spare parts from Märklin (only complete new decoders). Same is with me, I did the best to avoid any "bugs", but I cannot made liable for any damage occurring if you follow this text.

First you have to lift the container covering the electric engine. As Märklin has recognised by many damaged containers, you should pull it gently only in the directly upward direction, taking care of the 4 hooks fixing the container. Now you can see the relais mounted on the decoders printed circuit board just behind the engine (red arrow below). The cover of the decoder, which is mounted with another 8 hooks, can be removed beginning at he relais side using a small screwdriver.

After you have removed the two Philipps screws, you can take the decoder gently out of the pit. Looking at the description of the 60902 you can see that the type of connection of the pin for F4 of IC1 (701.22B) causes that either an external function or the internal delay on/off function is used. If this pin 18 of IC1 is connected to electric ground (pin 10) (or a transistor connected to it) the internal function is disabled. If the pin can float free, the internal function is enabled. So: warm up your SMD soldering iron (shouldn´t be the one for plumbing), warm up the pin 18 (marked with the red arrow below) and gently lift it from the solder pad. If you are shure, that you will not go back, you may fix the pin with a small drop of glue in the isolated position.

That´s it ! Now you should mount the decoder again with the two screws and test it. F4 now shows the internal function switching off the delay when activated.

If you want to use functions F1 to F3 additionally, you should be aware of that pins 15 through 17 are connected to electrical ground too. So you must lift them the same way as pin 18 to get them free of electrical ground.

At the right top side of the decoder printed circuit board you can see the simple ciruitry for switching between the two pick up shoes. The diagram for that can be found on circuitry for pick up shoe switch.

(c) Jürgen Schad, 15.11.2000