Hi Gents,

I came across an annoying issue last night when making some changes to a BR78 fitted with a loksound 3.0 M4 decoder.

The problem is that the lokprogrammer only supports DCC and MM protocols for testing and that the loksound 3 M4 decoder has different sound sync speeds when driving MM or MFX protocol.

This means when testing on the lokprogrammer track to sync the chuffs you need to use the MM protocol.

But then when you run the lok on the layout using MFX, the chuffs are way out of sync - too fast.


Unless someone knows of a formula for comparing the two protocols when testing, this means after programming on lokprogrammer I then need to move the lok to my layout to test with MFX.

Rather annoying!

Does the chuff sound frequency not relate directly to the speed step being applied? If so I'd expect that the speed step is the speed step regardless of which protocol selects it (DCC, MM, MFX).
However if you remap the speed step range (so that 255 is the Vmax you have set for the loco, and not the highest speed step the decoder could produce) that this creates a mapping from input speed step to output to the motor. Can you adjust your chuff frequency based on that ratio (Vmax set / 255) or some such thing?

This is just me guessing without actually having played with chuff settings on a decoder.

The problem is the MM protocol is 28 speed steps and MFX with 128 speed steps handle the sound chuffs completely different.
What happens is if the sound chuffs are synced (and yes for 2 cylinders) when I test with lokprogrammer using MM protocol its fine.
When I then test on my layout using MFX, the speed chuffs are about 4 times faster!

With the newer loksound 4.0 M4 decoder it is not a problem because you can test with DCC 128 speed steps but the older loksound 3.0 M4 does not support DCC so you can only test using MM on the lokprogrammer.

I think I will just need to program and then transfer to layout to get the speed chuffs right

Heh, as discussed on the phone definitely not:)

I took your advice though and first loaded the decoder defaults and found the motor operating correctly again.

I then loaded the ESU BR78 project that is included and proceeded to change all the values to my old project to copy the settings.

Motor is operating correctly again and with my desired settings.

Not sure what happened there, something went bad with the decoders settings as though max and min speed were both set to 1 or something.

Still need to test and get the sync correct for the chuffs but I think it might be correct after the last changes.

Incidentally I still have the same problem from the original post.
I have posted on ESU forums but no reply there either.

Hi Lasse,

The problem is not being able to test using the lokprogrammer whilst programming. It is labour intensive to continually swap the locomotive from the lokprogrammer over to the layout and then re-register each time (MFX re-registers after any lokprogrammer change).

Loksound 3.0 M4 decoder does not support DCC.
There is no problem with the newer loksound 4.0 M4 as these also support DCC (in additiona to MFX) so you can program and test with DCC using the lokprogrammer. DCC and MFX remain in sync as they use the same speed steps.