Spectrum USRA 2-10-2 light and MRC sound decoder

[SteamGene]

Is it necessary to cut the capacitors on a DCC equipted 2-10-2 to install an MRC sound decoder?
Gene

[Jim Banner]

If MRC's sound decoder is a silent drive decoder, that is, uses high frequencies to drive the motor, then yes, you should remove the capacitors.  But MRC may not tell you whether or not their decoder has silent drive.  I was thinking of your question this morning while installing an MRC 1650 decoder.  Nowhere in MRC's literature does it say "silent drive" or "ultrasonic drive" or any of the other buzz words and yet it was much quieter than most non-silent decoders.

Bottom line, if you know it is a silent drive decoder, you can leave the capacitors in.
If you know it is not a silent drive decoder, then you should take them out.
When in doubt, chop them out.   It won't hurt anything and may save a trip back into the locomotive.

[SteamGene]

That's what I 'm thinking, Jim.  OTOH, there are four capacitors, two easily clippable, and two hard to clippable. 
Gene

[Scott S]

Jim,
Re:
> if you know it is a silent drive decoder, you can leave the capacitors in.

Don't you mean the other way around - if it is a silent drive decoder, the capacitor(s) must be cut, otherwise not? I thought the LC (inductor-capacitor) circuit which we disable be cutting the capacitor was intended to limit the RF emission of the drive electronics but has a compatibility issue with silent-drive decoders.