idlemarvel
Neither idle nor a marvel
First a bit of background to set the scene for this posting.
To retrofit sound to a loco which already has a motor decoder fitted presents a number of alternatives:
1 – Replace the motor decoder with a motor and sound decoder
2 – Add a SUSI enabled sound module (if the motor decoder has a SUSI interface)
3 – Add a sound only decoder alongside the motor decoder
From a configuration or programming point of view option 1 is the easiest as there is only one address and range of CVs to customise. Option 2 has the same benefits of single address and range of CVs but not all motor decoders have a SUSI interface. With option 3 you normally set the address of the sound decoder to the same one as the motor decoder. This is to make it easier to control from your throttle, and so that engine sounds change as the loco goes faster or slower in synch with the motor decoder.
So here is the problem with option 3. Each decoder can have the same CV, but with different meanings. To take the LGB motor decoder and Massoth S decoder as examples, they both have CV49 but for the LGB it is used to set the voltage on function output 1, whereas on the Massoth it is used to specify serial/parallel commands, back EMF and SUSI or LGB bus. Or they may have CVs with the same meaning but you want different values in each decoder. If you try and read a CV and they are set to different values you get some kind of read error, and if you try and write you cannot specify which decoder you want to update. (I think some more recent sound only decoders have an additional "virtual address" to get around this latter issue.)
Normally the way around this requires opening the loco up, unplugging the sound decoder and programming that separately with a direct connection. However in the case of LGB locos with LGB decoders there is a simpler way. You may know that most LGB locos have a 4 way switch, usually inside the cab, that enables you to turn off the loco, or have just light and smoke, or be fully operational. What I discovered is that even if you turn this switch to position 0 so the motor decoder has no power, there is still power to the Track power outlets to which you normally attach the sound decoder..
The result of this is that if you set the switch to position 0 while the loco is on the track you have direct access to the sound decoder and only the sound decoder. As the sound decoder is still attached to the loco circuit board that seems to provide enough "ballast" for reliable read/writes. This works for programming track (service mode) or programming on main. I have tried this successfully with Massoth S sound decoder and the LGB diesel sound module 65006.
There may be other ways around this problem but I pass this on in case this is not common knowledge.
To retrofit sound to a loco which already has a motor decoder fitted presents a number of alternatives:
1 – Replace the motor decoder with a motor and sound decoder
2 – Add a SUSI enabled sound module (if the motor decoder has a SUSI interface)
3 – Add a sound only decoder alongside the motor decoder
From a configuration or programming point of view option 1 is the easiest as there is only one address and range of CVs to customise. Option 2 has the same benefits of single address and range of CVs but not all motor decoders have a SUSI interface. With option 3 you normally set the address of the sound decoder to the same one as the motor decoder. This is to make it easier to control from your throttle, and so that engine sounds change as the loco goes faster or slower in synch with the motor decoder.
So here is the problem with option 3. Each decoder can have the same CV, but with different meanings. To take the LGB motor decoder and Massoth S decoder as examples, they both have CV49 but for the LGB it is used to set the voltage on function output 1, whereas on the Massoth it is used to specify serial/parallel commands, back EMF and SUSI or LGB bus. Or they may have CVs with the same meaning but you want different values in each decoder. If you try and read a CV and they are set to different values you get some kind of read error, and if you try and write you cannot specify which decoder you want to update. (I think some more recent sound only decoders have an additional "virtual address" to get around this latter issue.)
Normally the way around this requires opening the loco up, unplugging the sound decoder and programming that separately with a direct connection. However in the case of LGB locos with LGB decoders there is a simpler way. You may know that most LGB locos have a 4 way switch, usually inside the cab, that enables you to turn off the loco, or have just light and smoke, or be fully operational. What I discovered is that even if you turn this switch to position 0 so the motor decoder has no power, there is still power to the Track power outlets to which you normally attach the sound decoder..
The result of this is that if you set the switch to position 0 while the loco is on the track you have direct access to the sound decoder and only the sound decoder. As the sound decoder is still attached to the loco circuit board that seems to provide enough "ballast" for reliable read/writes. This works for programming track (service mode) or programming on main. I have tried this successfully with Massoth S sound decoder and the LGB diesel sound module 65006.
There may be other ways around this problem but I pass this on in case this is not common knowledge.
