Fooling a decoder to think a motor is connected.

[hoovernut]

Goodevening 

I’m in the process of making a dummy class 27 with sound using a 21 pin socket. The question is can I fool the decoder to make it think that motor is connected so I can reprogram it. I have tried using some resistors but they get red hot to the point that the  solder melts on the connections to said resistors. 
I have put a meter across an old Hornby hst motor and that was around 80 ohms resistance.

thanks in advance.

 

 

 

[Lemmy282]

You'll need a high wattage resistor, something like 47R at 5 Watts.

[Dagworth]

Or simply a higher value, 470r 

 

Andi

[SamThomas]

Personally, I would invest in something like an ESU decoder tester.

 

 

[SRman]

I just plug the decoder into a powered locomotive temporarily, put that on the programming track, set everything I want to, then put the decoder back into the intended model.

There are certain locomotives that have bodies that just clip off easily, so those are the ones to use for reprogramming the difficult cases. For 8-pin decoders, any one of my Lima/Hornby class 73s work nicely, for 21-pin decoders it is a little bit more messing around, but I pick something that needs only one screw removed to get at the socket. or a Hornby sound-fitted class 60 (an earlier one with ESU decoder).

[dpgibbons]

The ESU decoder tester mentioned above is a great investment if you have a lot of decoders with a variety of sockets. I paid about GBP30 from AliExpress.

[hoovernut]

Many thanks for the help I will source some bigger resistors. 

[Andy7]

I think you are just trying to code a decoder in a non motored model, am I correct?

 

If so just code it together with any other motored model at the same time to the address you want the non motored to be. Then remove the non motored and code the motored model you used back to its original address. All the CV settings would remain set as they are saved on the decoder.

[SRman]

1 hour ago, Andy7 said:

I think you are just trying to code a decoder in a non motored model, am I correct?

 

If so just code it together with any other motored model at the same time to the address you want the non motored to be. Then remove the non motored and code the motored model you used back to its original address. All the CV settings would remain set as they are saved on the decoder.

 

That works well for most such cases, especially where you don't need to read the actual values in the unpowered vehicle's decoder. However, recently I had to do a bit more in a dummy driving car, to allow me to set individual marker lights separately in both the dummy car and the powered car, using separate functions for each. To do that, I had to put the trailing car's decoder into the powered car to be able to read it properly, without getting the other decoder's values in error, and changing them to the wrong settings.

I have used the shared programming track process with DMUs in the past, remembering to set CV29 to an odd number to reverse the trailer (actually reversing the setup for both coaches initially), then later on reprogramming the powered car back to what it should be.

The car at this end in the photo is the dummy. The three individual markers above the cab were route indicators for the signal men, and can now be lit in any combination, in the forward direction only. The two outer markers also contain the red tail lights.

Edited December 19, 2021 by SRman

[pauliebanger]

What sound decoder are you using?

[Oldddudders]

15 hours ago, SamThomas said:

Personally, I would invest in something like an ESU decoder tester.

 

 

I haven't understood how a decoder tester helps with the programming problem the OP has specified. 

 

[trevora]

31 minutes ago, Oldddudders said:

I haven't understood how a decoder tester helps with the programming problem the OP has specified. 

 

It,s got a motor

[hoovernut]

3 hours ago, pauliebanger said:

What sound decoder are you using?

More than likely a zimo chip with digitrains sounds.

[hoovernut]

8 hours ago, Andy7 said:

I think you are just trying to code a decoder in a non motored model, am I correct?

 

If so just code it together with any other motored model at the same time to the address you want the non motored to be. Then remove the non motored and code the motored model you used back to its original address. All the CV settings would remain set as they are saved on the decoder.

You are correct Andy. I took the motor out as it needs to be completely free running as I intend to just add it when double heading. On the plus side because it’s an old Lima there is plenty of room for an EM2.

[markw]

Not having a motor connected does not prevent writing to a decoder, it prevents the acknowledgement.

So single CV writes will still work, where the command station is writing more than one CV like the decoder ID it may stop after writing the first CV with an error message. You can calculate the values and write the CVs singly.

For  Zimo decoders setting CV112 bit 1 on will allow acknowledgement without a motor connected. Setting CV112 to 6 should be ok for most people but you may need to check the manual if you use Marklin brake mode or LGB pulse recognition.

[pauliebanger]

Mark has explained why it may not be necessary to have a motor connected in order to programme ZIMO sound decoders, so there's not much to add to that.

 

On ZIMO decoders, CV112 is a 'composite CV' in the same fashion as CV29 so some care is required when amending values.

 

A ZIMO decoder from Digitrains is likely to already have in CV112 a value of 32, so to add 'High Frequency Acknowledgement' instead of short bursts of power to the motor you need to increase the value by 2 so that CV112 = 34.

 

How effective this feature operates is ultimately down to the DCC controller you are using.

 

Being conscious that in order to allow future acknowlegements in this way you first have to change a CV (i.e., do some programming) you may find the need to change CV112 by POM (Programming On the Main). 

 

Or if you've not yet bought the decoder, ask Jeremy or John at Digitrains to set CV112 = 34 before sound loading. That way, if you need to reset in future, it will will remain at or revert to CV112 = 34.

 

Best regards,

 

Paul