Hi,

I am new to this forum. Just posted my introduction a minute ago.

When I had bought all the k73 decoders that where available for a reasonable price on eBay, I started to look for alternative solutions for my CS2 and the rest of my M-turnouts. I ended up buying three m83 decoders. While they all work perfectly, I cannot understand the very annoying noise they make. It is a very high pitched noise, almost like a bunch of grasshoppers and causes my wife a headache. Here is what I have tried so far:

I disconnected all the decoders. They became silent as expected. Then I connected track power to the first one. The decoder was still silent. After this I connected the yellow wire to one of my turnouts. Now the noise started. First as a fairly loud burst when I connected track power then getting more silent but still clearly audible. The noise increased every time I connected a new turnout and finally became as loud as before.

The noise seems to be related to the MFX or DCC activity in the system. For instance, during uploading of the CVs for a locomotive it gets very loud.

All three decoders behave the same way. There are small differences in the noise level that probably depend on the placement of the decoder and maybe what is connected to it.

Has anybody else had a similar problem? I have tried to ask Märklin but they just seem to ignore my inquiry. I remember having seen somebody asking about something similar about a year ago but cannot find the post. It would not help either because as far as I can remember it ended without any conclusion.

Thanks and best regards,
Lars

I concur that it is common (design) issue and can be distracting to varying degrees.

The activity appears to be the power supply (regulation) stage and is worse immediately after poweron as it "charges up".
I would hope that Marklin produce a redesign that uses (or produces) a higher non-audible harmonic in the power supply. Don't hold your breath.

It concerns me that, if you are recovering from a layout short (derailment), this activity may mute the ability for the CS2/Booster to correctly/quickly detect if the short is resolved - or otherwise.

Running your accessories of a separate booster is always desirable , to remove that load from otherwise being used for the track/locos.
The m83 (60831) may also have its power supplied separately from a DC power source 66361/66365. This mutes but does not eliminate the noise.

I feed mine with the 60822 external feed thingy and an MS2 power source. It makes the noise go away. My guess is that the sound (in my case anyway) is caused by the digital signal.

I am not sure, but I have had 10 running (m83/m84) with no problem what so ever. I guess you could calculate it by measuring the power consumption and holding it against the 36VA that the power source gives you.

Yes, the noise is definitely related to the digital signaling. My m83s were very noisy when for instance uploading CVs from the locos like I said in the first post. That would explain why Martin was able to silence his with a dedicated booster and Soren with a separate trafo.

Btw. Soren are your m83s totally silent or do they still make a weak high pitched noise? Is there anything special to consider or do you just hook up the 60822 and leave the track power wires as they are? I have a separate trafo that I use for the lights on my layout but I don't want to spend money on a 60822 if it does not improve the situation.

Thanks,
Lars