Testing DCC fitted loco's on DC power?

[plasticbasher]

Hi All,

 

I've just got hold of a DCC fitted loco (Hornby R2206 loco-drive 'Coronation') courtesy of a well known auction site.    My Xmas present to myself (ahem...from the children / cat / local foxes or something!!)

 

It was not originally DCC fitted, but appears to be hardwired very professionally / neatly.

 

​After receiving it this morning, I had to take the loco body off to sort the valve-gear as a piston had partly popped off the slidebars.  Testing by applying power without addressing that would have probably resulted in bent metal and the only proper way to relocate it was to release the cylinder block from the chassis and reassemble.  I suspected that to be that case after examining the listing photo and so bid accordingly.  As far as I'm concerned, that's defensibly "as described" and it only took 10 minutes of my time.  A missing body securing screw under the cab wasn't mentioned in the listing but it'd be churlish to get upset because of that - I easily found a suitable replacement.

 

​When I place the loco on my test track and apply DC power nothing happens.  No movement or indication any power is reaching the motor.

 

I can't see the brand of decoder as it's wrapped in tape (which I don't want to remove yet in case there is a problem) and I haven't contacted the seller yet as I am aware some DCC chips don't allow (or can be programmed not to allow) running on DC.

 

To be clear, the loco was listed as DCC fitted; and I plan to revert it to DC.  The seller also has top-notch feedback stretching back quite some time, so I'm confident he / she wouldn't have knowingly misrepresented.  And I'm good with how to deal with the seller if there is a problem.

 

​My query is a purely technical one:  Will I do (or risk) damage to the chip if I apply 12v DC power direct to the motor?  Logic says I won't, but I don't want to fry the chip on a loco that may need returning if the (£25+ to replace) motor is goosed?

 

​TIA,

​plasticbasher

Edited December 23, 2017 by plasticbasher

[smokebox]

Yes it will (probably/often) destroy the decoder if you apply power direct to the motor without disconnecting the decoder from the motor first.

Edited December 23, 2017 by smokebox

[johnb]

I suspect the chip has the 'run-on-DC' option turned off. If you are going to stay with DC then I suggest that you remove the chip and fit a blanking plug. It is quite possible for someone with a DCC system to get the DC option turned on. However the loco then takes quite a bit of power to wake up the chip and get it to run.

 

Personally I would not risk supplying DC to the motor with the chip plugged in.

 

Hope that helps

John

[Stephen Freeman]

Hi All,

 

I've just got hold of a DCC fitted loco (Hornby R2206 loco-drive 'Coronation') courtesy of a well known auction site.    My Xmas present to myself (ahem...from the children / cat / local foxes or something!!)

 

It was not originally DCC fitted, but appears to be hardwired very professionally / neatly.

 

​After receiving it this morning, I had to take the loco body off to sort the valve-gear as a piston had partly popped off the slidebars.  Testing by applying power without addressing that would have probably resulted in bent metal and the only proper way to relocate it was to release the cylinder block from the chassis and reassemble.  I suspected that to be that case after examining the listing photo and so bid accordingly.  As far as I'm concerned, that's defensibly "as described" and it only took 10 minutes of my time.  A missing body securing screw under the cab wasn't mentioned in the listing but it'd be churlish to get upset because of that - I easily found a suitable replacement.

 

​When I place the loco on my test track and apply DC power nothing happens.  No movement or indication any power is reaching the motor.

 

I can't see the brand of decoder as it's wrapped in tape (which I don't want to remove yet in case there is a problem) and I haven't contacted the seller yet as I am aware some DCC chips don't allow (or can be programmed not to allow) running on DC.

 

To be clear, the loco was listed as DCC fitted; and I plan to revert it to DC.  The seller also has top-notch feedback stretching back quite some time, so I'm confident he / she wouldn't have knowingly misrepresented.  And I'm good with how to deal with the seller if there is a problem.

 

​My query is a purely technical one:  Will I do (or risk) damage to the chip if I apply 12v DC power direct to the motor?  Logic says I won't, but I don't want to fry the chip on a loco that may need returning if the (£25+ to replace) motor is goosed?

 

​TIA,

​plasticbasher

Theoretically you can run DCC locos on DC (run on DC is on by default but could have been switched off) however, it all depends on the DC, Feedback types are a definite no no. Best to remove the chip if you are planning on using it on DC.

[Nigelcliffe]

 Will I do (or risk) damage to the chip if I apply 12v DC power direct to the motor?  Logic says I won't, but I don't want to fry the chip on a loco that may need returning if the (£25+ to replace) motor is goosed?

 

 

 

Almost certainly damage the decoder if you do that.  

You MUST disconnect the decoder before putting 12v (or any DC volts) onto the motor.  

[RAF96]

If it is hardwired rather than a plugin decoder and you want to go back to a DC forever rig then just snip the decoder wires off and connect the red (right wheels) and orange (one motor brush) together and the grey (other motor brush) and black (left wheels) together.

 

A steam loco will generally only have these four wires from the decoder connected to anything, with the blue, white, yellow and green taped up if there at all.

 

Edit: A simple test to check if a DCC loco is DC enabled is to press the terminals of a 9v brick battery across the wheels. As stated never apply voltage direct to the motor brushes or the decoder dies.

 

Rob

Edited December 23, 2017 by RAFHAAA96

[plasticbasher]

​Thank you all very much for the replies.

 

Was hoping I could test the loco without removing the chip (yes it's hardwired, there's no DCC plug and yes there are about 4 other wires that have been taped off).  Removing the chip means I have to accept the risk the motor is good...in principle it should be, but until tested I cannot be sure.

 

​Learnt my lesson...don't buy a DCC-fitted loco if I want to test it before providing the seller with feedback!  That...or buy a DCC controller... :-D

 

​plasticbasher

[paftrain]

​Thank you all very much for the replies.

 

Was hoping I could test the loco without removing the chip (yes it's hardwired, there's no DCC plug and yes there are about 4 other wires that have been taped off).  Removing the chip means I have to accept the risk the motor is good...in principle it should be, but until tested I cannot be sure.

 

​Learnt my lesson...don't buy a DCC-fitted loco if I want to test it before providing the seller with feedback!  That...or buy a DCC controller... :-D

 

​plasticbasher

 

If you can find a friend who has a DCC controller you can see if it runs ok on DCC. If so, then ask them to change the value of cv29 to allow dc running. No need to strip or rewire anything!

[drgj]

Is it correct that running a DCC loco on DC damages the chip? I thought you could run them on either. Bachmann locos I thought would be ok on either as are Hornby. I am new to DCC. Is it only some chips? I know that a DC loco might be damaged if stood on a DCC system.

 

Dave

Edited February 10, 2018 by drgj

[RAF96]

Is it correct that running a DCC loco on DC damages the chip? I thought you could run them on either. Bachmann locos I thought would be ok on either as are Hornby. I am new to DCC. Is it only some chips? I know that a DC loco might be damaged if stood on a DCC system.

 

Dave

As you surmise - Its the other way round. Do not stand a DC loco on a DCC track for any length of time as the motor will see full +/- 15vDCC across its coils - an average of zero volts but in truth it will buzz in protest and get warm/hot then possibly burn out.

 

The other way round - DCC on a DC track no problem as the decoder recognises DC if as stated earlier DC running is enabled in CV29.

Edited February 10, 2018 by RAFHAAA96

[royaloak]

Is it correct that running a DCC loco on DC damages the chip? I thought you could run them on either. Bachmann locos I thought would be ok on either as are Hornby. I am new to DCC. Is it only some chips? I know that a DC loco might be damaged if stood on a DCC system.

 

Dave

Putting 12V to the wheels is fine and wont do any damage, putting 12V directly to the motor will zap the chip, its not the 12V which is the problem but which side of the chip you are putting it because a chip is designed to receive the voltage from the track side not the motor side.

[Silver Sidelines]

Hi Dave

 

A lot of ' out of the box' digital fitted Bachmann engines will run on analogue DC.  Jubilee Alberta comes to mind and the original Blue Pullman.

 

Is it correct that running a DCC loco on DC damages the chip?

 

However as already said in this thread, it takes a certain amount of power to 'wake the chip up' and digital fitted locomotives will not run as 'fast' on analogue as they do, without the chip.  I only run analogue DC and I take the chips out and replace with a blanking plate.

 

Important exceptions are Bachmann digital sound locomotives with LokSound v3.5 and v4 chips which are mostly analogue DC enabled - and will play sound on analogue DC. Coincidentally I have just acquired a digital sound 'Sea Eagle' - I am well impressed with the running and sound on analogue DC.

 

http://youtu.be/HBOpHA6NY78

 

I will digress and add that Hornby TTS engines are designed to work on analogue DC and run and perform as expected without any need to remove the chip.  However unlike Bachmann locos fitted with LokSound decoders, the TTS chip will not play sound on analogue DC.

 

Regards

 

Ray

 

PS I am sorry that this doesn't address the original question where the chip is hardwired.  I bought  a Sprog to connect to the laptop to run and test digital fitted locomotives.

Edited February 10, 2018 by Silver Sidelines

[Crosland]

Is it correct that running a DCC loco on DC damages the chip?

 

No but if you re-read the posts you will see that is not what is being discussed.

[drgj]

Thanks to all. Not really a digression as in the first post my  question is asked in bold type and there were conflicting answers.

 

Dave

[Oldddudders]

Thanks to all. Not really a digression as in the first post my  question is asked in bold type and there were conflicting answers.

 

Dave

 

When a DCC-equipped loco is 'set up' by the owner, then CV29 options will be set to either include or exclude DC running. Many of us exclude it, because if a DCC layout suffers a short - e.g. a loco runs through a wrongly set trailing point - any DC-enabled locos on the layout may set off at warpspeed, because they have just seen a brief flash of pure full-volts DC during the short. So the answer is DCC locos run happily on DC if their owner has enabled that option in CV29.

[GoingUnderground]

I have seen posts where modellers have been advised not to run DCC fitted locos on DC, but the key info in these posts is the age and design of the DC controller. Those more knowledgeable than I about DC PSUs have said that some older DC controllers can, under certain circumstances, produce voltage spikes at their outputs that exceed the permitted maximum voltage for decoders. So the risk isn't DC power, but the DC controller misbehaving. I'm sorry but I can't give you any further info on which DC PSUs have this problem, and the circumstances that could give rise to them producing voltage spikes.

 

Don't run a DCC fitted loco on a layout which has a high frequency track cleaner, like a Relco, in operation as they can in certain circumstances damage decoders.

 

Decoders are designed to output power at their motor terminals, not have a DC power source applied to the motor outputs which is what you are doing if you apply power to the motor when the decoder is still connected to the motor. If you do, you will very probably blow the decoder.

 

If you want to test a DCC fitted loco on DC then use a 9 volt battery as your power source, and only apply it to the wheels. Don't try connecting it to the motor if the decoder is still connected. The battery is just as likely to severely damage the decoder as power from a DC PSU.

 

If the motor won't run when using the battery applied to the wheels, the decoder may have the option on running on DC turned off. In this case your only options are to find someone with a DCC controller who can read the decoder to see if this is the case, and if so they can set up the decoder to run on DC.

 

However, some decoders which will work with DC power will only do so with smoothed DC, such as power from a battery. I'm thinking of some decoders from the ZTC range, specifically their older 255 and 258 decoders. Many older mains powered controllers use simple rectification of the outputs from their mains transformers to give unsmoothed DC outputs. These particular ZTC decoders won't work with unsmoothed DC even when set up to run on DC, and I speak from personal experience of these decoders from several years ago. I don't know if this still applies to newer ZTC decoders.

Edited February 12, 2018 by GoingUnderground

[Sir TophamHatt]

Is there an advantage to setting the "run on DC" option to off if you're always going to run on DCC?

[Oldddudders]

Is there an advantage to setting the "run on DC" option to off if you're always going to run on DCC?

 

Post 15?

[Phil S]

Phil: whilst my preference (perhaps having taught the maintenance of electronic equipment for many years) is to leave the DC running option ON - which is the factory default condition - and which would also be reinstated after any 'reset' to the decoder

 

THIS PERMITS simple testing with a 9V battery - a conveniently portable source (but do not SHORT in pocket or leave metal clad battery on the track !!)  - and provided wheels on the same axle have pickups .. otherwise a piece of rail is needed to spread the power transfer to some other axles/wheels.  (ALL decoders SHOULD work at track-voltages greater than 7V ... many from about 5V.

 

(Equally, if a newly wired loco runs in the wrong direction; rather than the quick fix of  changing the cv29 lsb value from 0 to 1, it is better to swap the wires to the motor.   Which direction it runs on dc should also be checked** (red wire to right rail, black to left))

This way I either programme [6]  into CV29 (for locos 1-99 (/127***) and [38]  (ie 6+32) for 4-digit addresses 100-  (128***) - 9999 ++

[LGB G Scale DEFAULT analogue running direction is the OPPOSITE WAY !! Hence Bachmann G Scale add a SWITCH in the loco.

 

[*** I use Roco Expressnet based controllers which follow the sensible  Lenz recommendation of 1-99 for 2 digit basic addressing, and then extended addressing for 100-9999 - matching the display characteristics and human readability .. rather than swapping at 127/8  .... but ZTC follow(ed) the nmra anachronism of changing at 128 making 100-127 a dodgly area for multi-layout stock !

 

OLD ANALOGUE CONTROLLERS such as H&M Clipper and the like ALL HAVE UNREGULATED OUTPUTS - which, although labelled as 12V dc or 0-12Vdc may be found to have a PEAK VOLTAGE ( 100x a second ) of about 28V when no trains are running... and may only drop to an AVERAGE of 12V at FULL CURRENT  ... because they are simply rectified off the transformed mains supply (which may reach 250-255V rms at times) ... and due to inefficiencies in transformers, which are rated to provide the quoted voltage at the maximum quoted current .... give out hogher votages at lower currents.

EG the Roco 230:16V transformers used in the UK could give 22V dcc on the track when no trains were running (it showed on the coach lighting !! )  ... but which are all now replaced, due to CE regulations for energy efficiency, with SMPS (Switch Mode (regulated) Power Supplies .. giving a constant 18Vdc (in the Roco example) which in turn give 16V dcc on-track  (which then drops in a decoder's rectifier and power stages to give about 12V maximum at the motor).

 

THE IMPORTANCE of the 'peak voltage' being that that directly affects what capacitors in the circuitry will get charged to ... NOT the 'average' or the rms.   SOME decoders, particularly for smaller gauges or from the USA may use 16V capacitors instead of 25V.

European manufacturers tend to use 25V or higher because their decoders are compatible with Marklin digital - and a 16V history

Triang Controllers (in the unregulated period -eg blue case with red knob - are stated to be 0-14Vdc.

In G_Scale, their analogue ran 0-24VDC  and their digital was 22Vdcc ... but now with Marklin manufacture, and SMPS supplies, they come with 18Vdc supplies ... I have not checked their output  track voltage recently.  We use Massoth (adjustable, 16-22V) and Roco for LGB on-the-level / indoors where the 16Vdcc on track is adequate.

 

Runaway avoidance MAY also be improved by removing the extra 3 capacitors that Bachmann add around their motors ???? )

 

I have not suffered from 'start-up runaways' for many years - since ditching my ZTC511 in favour of Roco Controllers 8-)

 

Since ZTC recommended a switch between controller an track to avoid the problem - it was perhaps a shame that the switch was not built in to the controller - so that  it could operate automatically  once it was ready with full voltage !   i also use PSX intelligent breakers to reinstate power after any outage causes by a short...such as derailment or overunning a live frog.

 

'runaways' I have still experienced have usually been down to wireless communications failures:   1-way Radio Controllers (LGB MTS) - with 8 handsets operating in 1 garden - not even the emergency stop commnad always got through - resuting in a few crashes on a popular open day (I've never since seen so many wireless handsets on 1 layout as were brought along that day! )

LOSS of SIGNAL - / interference due to other controllers on the same channel (Massoth Navigator before they increased the options) - interfering with the 2-way signal, and possibly local radio Control boats/tanks and planes in the neigbouring marquee causing loss of control on a 14m layout, if that controller was at the far end, and not 'held up' away from the layout.