Fitting DCC to Hornby 0-4-0 - conflicting advice

[john new]

I am somewhat puzzled by two conflicting articles on how to add a DCC decoder to the basic Hornby 0-4-0 as published in Model Rail. In my archived copy of the August 2017 article on DCCing the diesel the advice was remove both the capacitors, pictures 3-5 in the set clearly show two removed/none added, stating they are not needed with DCC. The query is - in the latest edition of MR the advice from Chris Gadsby is to leave one of them in. Other articles elsewhere have always advised removal of the capacitor/TV suppressor. The first article was about adding DCC via fitting a chip socket the second was for hard wiring if that makes a difference.

 

Which advice is correct? If both are correct in differing circumstances can someone please explain what the difference is as I am a relative newbie to DCC working. I have two of these to do, a Caley Pug (Smokey Joe type) and the CEGB Richborough liveried Barclay-ish diesel.

 

Edited September 23, 2020 by john new

[johnd]

Welcome to area of various thoughts.

Personally the Hornby models to which you going to fit decoders i have done a few of these for my personal use and in all of them have left the capacitors fitted  taking the view that if there was a problem they could always be removed. Never had a problem not one.

The other view is that remove it at fitting stage as its is not required as its function is supplied by the decoder.

You will meet those on here that adamant as to the removal before decoder fitting. In the end its up to you how you want to fit them to your locos. As I've said I've been fitting decoders for over 10 years and never had a problem ( will probably have one now) 

Who is to say who is right and who is wrong?

All I can say is fit a decoder where you can alter CV5  reducing it as this gives a lot more control and gives low speed control.

 

 

Edited September 23, 2020 by johnd

[Pete the Elaner]

It may also depend on what decoder you have & what you want to do with it?

Some decoders are better than others at coping with the capacitor in place. The decoder can read the motor pulsing as it turns. Sound decoders from Zimo & Loksound (but not TTS) use this to synchronise the exhaust beat of a steam loco. The capacitor can in theory 'blur' this pulse.

 

I agree with JohnD though. I cannot remember having an issue with the capacitor in place.

It is always good to test run a loco before re-fitting the body, so do this before you consider removing the capacitor & if the loco runs well, there seems to be no point in removing it.

[dan_the_v8man]

The other point to consider is removing the cap going to be detrimental?

 

I've never heard of anything detrimental from removal

[RAF96]

What can be assured is that if you leave the motor cap in place and it goes south it will invariably fail short and kill your decoder.

[johnd]

3 hours ago, RAF96 said:

What can be assured is that if you leave the motor cap in place and it goes south it will invariably fail short and kill your decoder.

Never had any problems and I've been using DCC for many years.! 

[Sir TophamHatt]

So really, it doesn't seem to matter.

Nobody has bought two locos and tested - and that's the only close way you'll truly know.

[john new]

I did email the magazine but have not yet had a direct reply, will be interested to see if it appears in a future edition in the Q & A section.

 

Edited October 8, 2020 by john new
Omitted word

[john new]

To add to the confusion, or provide a definitive answer, here are the Hornby supplied notes on how to do it. They add the capacitor back.

[melmerby]

3 minutes ago, john new said:

To add to the confusion, or provide a definitive answer, here are the Hornby supplied notes on how to do it. They add the capacitor back.

Even Hornby don't know what they're talking about.

The "red" capacitor is not a capacitor, it is a choke (inductor)

[john new]

10 hours ago, melmerby said:

Even Hornby don't know what they're talking about.

The "red" capacitor is not a capacitor, it is a choke (inductor)

What does the choke do and is it needed? That may be a mis-described part that is mentioned in my first post after being stated to be a refitted capacitor in the second Model Rail article.

[melmerby]

7 minutes ago, john new said:

What does the choke do and is it needed? That may be a mis-described part that is mentioned in my first post after being stated to be a refitted capacitor in the second Model Rail article.

The choke is a coil of wire and it is originally in series from the pickups.

In combination with the capacitors it makes a filter to suppress unwanted high frequency artefects from DC motor commutation (sparking at the brushes generates a wide range of frequencies which can interfere with radio/TV reception*)

Whether any of it is needed after DCC conversion is debatable due to the different way the motor is controlled by the DCC decoder.

I normally don't remove the components if there is a socket for a decoder, If I have to do a hard wire, I do remove them as it's simpler for the wiring.

 

* Some of the earliest experiments in radio communication involved spark transmitters. A spark was generated across a spark gap and a long wire aerial was connected to one side and a ground connection to the other

The receiver was a long wire & ground connected to some basic detection device. No tuning was used as it was very wideband freqency generation.

These days they are illegal due to the mass interference they cause to other wireless transmissions.

[john new]

Finally attacked one of my oldest 0-4-0s today and found the question raised back in October to be academic. There was a suppressor across the motor terminals but no other wiring. The motor got power from sitting on the pickup which had vertical arms.
 

Other problems with the beast have prevented the final assembly but testing with the hard wired chip proves the motor does work on both DC and DCC; the problem is basically I can’t keep the gears in mesh or the pickups on all four wheels at the same time. I gave up in disgust after prolonged juggling without success. I will take a break and come back to it fresh in a few days time.

 

One has to wonder though, as the biggest problem is getting the worm to mesh, why Hornby ever decided the crude and fiddly method of using a bent bit of wire to hold the motor in place was a good idea, and having done so, then put it in the entry level train set!  It poses the question - how many prospective modellers has it deterred as their first model has this problem. Child drops it on the floor, comes unmeshed, nightmare for the parents to get it back working.

 

Edited December 31, 2020 by john new
Typo

[RAF96]

I wonder if a simple tie-wrap would work to secure the motor as per ESU decoder test rig. Anything has to be better than springy thing sticking out of the bodywork.

[john new]

Just an update.

 

Having now replaced the motor clip spring with a new one from Pete’s Spares (after being dropped the first disappeared completely) the repair has moved onwards. I have solved the meshing problem by adding a shim under the mounting screw; unfortunately a new issue is a short that only appears with the spring in place so I still have a loco I can’t run. This is going to need tracing and some insulation added in due course.

Why am I bothering with a 2nd hand loco, still in need of some bodywork TLC, and which would be easy to replace? I am guessing a sort of masochistic desire not to be beaten - it sat in the get around to fixing it someday pile for so long (at least 11 years) that I don’t want to let it win!

 

 

Edited March 2, 2021 by john new
Clarity

[john new]

First opportunity today to get back to this and it now runs on DC & DCC. Still a bit (1) stopped or (2) off the grid like an F1 car but progress. A good test piece for working later on my 0-4-0 diesel. The diesel will look at home on the layout, Caley liveried Pug an occasional only.

 

Next item up, but non-urgent, how to get extra pick-ups fitted. 

 

Edited March 2, 2021 by john new
Saved by accident whilst still editing it!

[RAF96]

Recent forum activity suggests that these more modern variant 0-4-0 locos may be fitted with a resistor to tame the motor. If this resistor is removed as part of the DCC conversion clean up then it is going to affect the basic running characteristics.

[john new]

2 hours ago, RAF96 said:

Recent forum activity suggests that these more modern variant 0-4-0 locos may be fitted with a resistor to tame the motor. If this resistor is removed as part of the DCC conversion clean up then it is going to affect the basic running characteristics.

That makes sense on two counts -

 

1) why it is on later but not early one’s.

2) improving running.

 

When I next order some bits from an electronics supplier what resistance is suggested?

 

Edited March 5, 2021 by john new

[Pierre Le Brun]

This week I removed a  laisdcc decoder, which never worked, from my Smokey Joe and replaced it with a Gaugemaster Ruby Decoder. I had previously removed the capacitor and resistor from the motor. I can now  run Smokey Joe with the new decoder at a realistic speed and not like a scalextric car.