Hard-wiring a decoder to a Farish Class 14 - banish the PCB?

[BusDriverMan]

Hi folks,

 

My mission for tomorrow is to hard-wire a decoder to a Farish Class 14 that's been decorating my desk for six months.

 

I successfully wired up a Farish 04 before, but that was far roomier inside than the 14!

 

I saw a comment on a locked thread about another N-gauge low-bonnetted diesel - someone saying he'd remove the DC motor PCB to get the precious extra millimetres. And the decoder manual (Digitrax DZ126T) mentions I should remove RFI capacitors in the locomotive wiring. Is that what the PCB on the end of the motor is, with its two capacitors - should I remove it?

 

[BusDriverMan]

The two capacitors are in series across the motor terminals - same as the 04. More research says they're not needed when used with a decoder, and interfere with the decoder's speed control.

 

I removed the capacitors from the PCB on the 04 I'd previously wired, and low-speed performance immediately improved.

 

I removed the entire circuit board on the 14 by removing the motor and using desoldering braid, and the tags on the motor are much easier to solder wires to than the PCB surface.

 

Conversion is complete now! Runs nicely and slowly.

[Paul80]

Hi

 

I removed the complete PCB on my 14 and 08 and the slow speed running was vastly improved, its only held in place by two solder joints so easy to remove, you then just connect the orange and grey wires to the two points where the PCB was soldered.

 

a simple job well wort doing.  the hardest part with the 14 is routing the wires so they don't get crushed when the body is refitted, IIRC they need to be routed down the side of the chassis not over the top.

 

Paul

[BusDriverMan]

10 hours ago, Paul80 said:

the hardest part with the 14 is routing the wires so they don't get crushed when the body is refitted, IIRC they need to be routed down the side of the chassis not over the top

 

 

 

That's what got me :/

 

The tight spots are:

 

a) the gap between the top of the chassis and the inside of the long bonnet end - the chassis needs filing down to make space for the decoder

 

b) the gap between the gearbox cover and the cab interior moulding, the middle one with the driving controls

 

I tried to reassemble with too much wire on top of the gearbox cover, and popped that cab interior moulding loose. Not easy to put back without removing the entire cab from the running plate and I don't think that's possible - so might just live with it!

[Nigelcliffe]

I converted one of these for someone many years ago (decoder plus 2mm finescale wheels).  I thought I'd taken photos, but can't find them. 

 

The decoder required filing down the chassis at the opposite end to the motor to create a suitable space.  Not hard if chassis is dismantled.  Wire routing just required care, and using suitably thin wires from decoder to motor - quite a lot of decoder wires are somewhat fat with chunky insulation.  Shopping around will find thinner insulation on the same section of wire inside.  If really stuck, then "winding wire" (single strand, insulated with a varnish coat) can be used - I have a variety of sizes.

[Steven B]

I left the motor mounted PCB intact but removed the cab interior when I converted mine.

 

Steven B.