Converting a Class A2 (Possibly Trix) to DCC

[Smudge617]

Hi Everyone.

I recently purchased from everyone's favourite auction site, a Class A2,(Possibly Trix)  but I'm a little (read very), confused as to where I need to attach the DCC harness, as I don't understand how the motor wired up. (Electrics are not my strong suit as RAF can testify) as you can see, the motor is similar to a X03/O4. The Red and Green wires come from the tender pickups, that I get, but the two red covered wires to the front are a mystery, my understanding is that they should connect to pickups either side of the frame or one side via contact through the chassis from one of the two centre wheels, (others being fitted with traction tyres), but there are no pickups, and both wheels are insulated. When it arrived the green wire was not attached, but the motor ran when tested, so I know it's receiving power from the opposite side of the track via some part of the loco, therefore the two red wires are for something, and they don't look like capacitors that I've seen before, so do I simply wire in the the harness from these (observing polarity if I add the tender pickups) and then add the power from the harness to the motor as per an XO3/4. Or insulate the motor, and just use the tender pickups to power the motor. Any help would be appreciated.

[John ks]

The red things are Inductors or chokes for RFI & should not be necessary for DCC

 

I Would remove all wires, connections ( including the chokes) to the circuit board (for the brushes) on the motor & remove all solder from it so that you have a clean surface to start with.

 

This should isolate the brushes from the frame of the loco (check with a multimeter to ensure the brushes are isolated from the chassis & all pickups)

 

in the picture i have added a red & black line to show where i think the chokes are connected, the black looks to be connected through the choke to the chassis. The red looks to be connected to a lug on an insulating board. the red wire from the tender may have originally been connected to the other lug on this board.

The green wire is connected from the tender to the loco chassis

 

Connecting DCC using NMRA colour codes

Red wire from tender to  decoder Red wire   (usually connected to the pickups from the right hand side looking forward)

Green wire from tender to chassis & decoder black wire    (usually connected to the pickups from the left hand side looking forward)

Orange wire from decoder to motor brush (marked Or on circuit board

Grey wire from decoder to motor brush ( marked Gy on circuit board)

 

 

 

The 2 wires poking out of the motor brush circuit i have marked "spring" look to me to be one end of the brush tensioning springs

Provided that none of the copper tracks on the motor brush Printed board are touching the chassis or motor frame this conversion should be doable.

Hope this helps 

John

 

 

 

 

 

[Smudge617]

Thanks John, much appreciated, Your explanation is brilliant, and easy for a novice like me to get their head around. I'll let you know how I get on.

Edited October 11, 2021 by Smudge617

[Smudge617]

Just to keep everyone updated, as to how this is all progressing (apart from slowly).

Power was coming from the chassis via one side of both pony units on the loco, other side, via the tender pickups, so one side was picking up from the tender and the loco, other side just the tender, the red parts are indeed suppressors and removing them from the board isolates the motor. So I can power the loco via the decoder by just using the tender pickups. But I will have to solder directly onto the brushes as todays brushes are too wide to fit in the slot, and, ingeniously I thought, the springs holding the brushes are fitted under the top of the motor.

Edited October 16, 2021 by Smudge617