Advice installing a decoder in a Fleischmann BR78

[smokeyone]

Hello

 

I am hoping some forum members might be able to offer guidance on installing a decoder in a 4-6-4 Fleischmann steam loco.

I have googled and have found out about Fleischmann motor backplates and maybe how to insulate them but this models backplate is a little different.

It could be a case of just cutting the correct wire.

Also there already seems a place to put the decoder chip and are the lights already Led's or really small 12v bulbs..

 

Many thanks

Edited June 30, 2021 by smokeyone

[John ks]

7 hours ago, smokeyone said:

really small 12v bulbs..

They are really small bulbs

They will work on DCC provided their current draw does not exceed the decoder function output

 

If my knowledge of Fleischmann is correct then the lights are controlled by diodes which are a small disc between the lamp & its contact

(Represented by the grey disc in the drawing)

 

 

You need to isolate the motor brushes from the track pickups

Disconnect the red wire to the rear light at the motor

Disconnect the & remove the choke (is used for RFI suppression in DC it is not necessary for DCC)

Cut the bridge on the circuit board that holds the brushes (marked on the drawings)

Once this is done the brushes should be insulated from the chassis & all wheels 

Use a multimeter to check

 

The 2 drawings represent the before & after electrical connections in the loco

The thick blue line represents the metal chassis of the loco

 

If the uninsulated wheels that connect to the chassis are on the left hand side of the  of the loco then the colour of the wires from the decoder will be to NMRA standards

If not then swap the red & black wires to the decoder(IE red goes to where black was & black goes to where red was)  & similarly  swap the orange & grey wires to the decoder

 

Regarding the lights 

Front light( cylinder end), disconnect the red wire from the pickup & connect it to the white wire from the decoder

Rear light  Disconnect the red wire at the motor end & connect to the yellow decoder wire

 

If one or both lights don't work as expected the the diode for that light can be removed , turned around & replaced or removed completely

 

The blue wire from the decoder is not needed as the lights get half wave DCC from the chassis

If you decide to go to LED,s then you will need a resistor for each LED & the blue wire from the decoder will need to be connected to each led

 

 

 

John

 

 

[smokeyone]

Hello John

 

Thank you very much for the detailed explanation. I was thinking of trying a Zimo 1amp decoder - Zimo in particular because I could experiment with ABC braking. I will report back on my progress but just curious as to what the tiny coil of wire does to the right of the right hand motor brush - you can just see it in the photograph taken from above.

 

Thanks again

[John ks]

1 hour ago, smokeyone said:

curious as to what the tiny coil of wire does to the right of the right hand motor brush

It is a choke, also known as an inductor 

It is there to reduce RFI (Radio Frequency Interference ) on DC & can be deleted on DCC

 

If I wasn't clear in the previous post the wire from the inductor needs to be unsoldered from  the RH motor brush & replaced with the orange wire from the decoder

 

If you wish to retain the inductor then the following drawing should help

 

 

 

John

[smokeyone]

Hello John

 

Thank you again for the advice - I'll order the Zimo and warm up my Soldering Iron.