DCC Sound Cuts Out on Hornby Crosti 9F. Adding Pickups. Help!

[DrStroganoff]

 

Hi guys.   Apologies if this is a bit rambling/wrong section etc...

 

Yesterday I did my first DCC sound installation on a Hornby Crosti 9F.   I used a Hornby TTS decoder, plus a bass-enhanced speaker from eBay.    The sound installation went fine, but this loco is terrible for stalling on my not-quite-flat points, and obviously the sound cuts out/resets.   The loco only picks up from the driving wheels,  so I figure I need to install pickups in the tender to help it get over the points without interruption.   Also, should mention the loco's polarity seems to be reversed.

 

I had a go at adding pickups, and that's when things got interesting...    I added bronze pickup strips to the front wheels of the tender, soldered some fine wire to the pickups and soldered the other end to the tabs on the motor.   I thought that was going to be 'job done', but no!

 

When the loco was placed on the track, a loud buzzing came from the decoder, but there was no short circuit.  Lifting the tender from the rails stopped the buzzing, but the loco was lifeless.   Swapped the wires over, and the layout shorted,  which suggests I had wired them correctly on my first go.

 

I disassembled the loco, detached the tender/pickups,  but left the new pickup wires attached to the locos motor tabs.   I then experimented with touching those wires to the rails, and the loco lunged forward at speed all of a sudden.    

 

This is all v weird.  I had hoped adding pickups would be the easy bit!     I'm thinking maybe I should strip the whole loco down and rebuild, removing any capacitors along the way.  Any thoughts?

 

Here are some pics of the inside of the loco,  tender pickup wires removed...    

 

Should I remove the capacitor?

 

 

Thanks for reading folks.   I'd appreciate any suggestions, although I realise my post might be a tad unclear!

[Hamburger]

1 hour ago, DrStroganoff said:

soldered some fine wire to the pickups and soldered the other end to the tabs on the motor. 

 

That reads as if you finally connected the track voltage via the motor directly to the decoder output?

Most of the decoders can't stand this.

[RAF96]

Never apply a direct voltage to the motor whilst a decoder is installed - 100% decoder kill.

[DrStroganoff]

2 hours ago, Richard Croft said:

I would guess that the decoder has failed, try the decoder in another, unmodified loco to confirm, if it doesn't work in that either you will know the decoder is at fault.

 

Richard

 

Thanks for the replies.     Richard,  I have tried the TTS decoder in another loco (streamlined coronation), and works fine.

 

 

1 hour ago, Hamburger said:

 

That reads as if you finally connected the track voltage via the motor directly to the decoder output?

Most of the decoders can't stand this.

 

I've connected my tender pickups directly to the tabs on the motor, to which the decoder is already connected.  Should I have not done this?

 

 

1 hour ago, RAF96 said:

Never apply a direct voltage to the motor whilst a decoder is installed - 100% decoder kill.

 

The decoder still works fine if the tender/extra pickups are not connected.  

 

 

I must apologise if I have not described the problem clearly.  I'm having trouble processing it myself!   

 

To reiterate, everything works as it should until extra pickups are introduced to the motor.   

[Hamburger]

14 minutes ago, DrStroganoff said:

To reiterate, everything works as it should until extra pickups are introduced to the motor. 

Any pickups must be connected only & directly to the black and red wires of the decoder.

Grey and orange wires must be connected to the motor only, nowhere else, not even chassis.

[Kaput]

Pickups do not connect directly to the motor when dcc is involved, its kinda the whole point in the decoder that it goes between the pickups and the motor. Your new pickups need connected to the pick up wires on the decoder.

[DrStroganoff]

13 minutes ago, Kaput said:

Pickups do not connect directly to the motor when dcc is involved, its kinda the whole point in the decoder that it goes between the pickups and the motor. Your new pickups need connected to the pick up wires on the decoder.

 

Thankyou Kaput,  this is what I needed to hear.   I think I see where I'm going wrong now.    

[DrStroganoff]

Just to follow up...    I ended up connecting my tender pickups directly to the loco's pickups with a couple of short wires.   Works perfectly now,  no stalling or sound cutting out.   

Edited January 9, 2022 by DrStroganoff

[Lemmy282]

I would remove the capacitor as well.

If the loco is still running the wrong way then either alter the value of cv29, or reverse the connections of the wires from the decoder socket to the motor.

[RedgateModels]

9 hours ago, Lemmy282 said:

I would remove the capacitor as well.

If the loco is still running the wrong way then either alter the value of cv29, or reverse the connections of the wires from the decoder socket to the motor.

honestly I wouldn’t remove the cap if the loco is running fine. I only remove them if running is erratic or I’m hard wiring a decoder to make more room for a sound decoder for example. I’ve only had to clip a cap on one Bachmann loco due to poor running characteristics.