# Anyone know what this sound module is?



## Brandon (Jul 6, 2011)

I bought a couple aristocraft engines (fa1 and u25b) and both have these sound modules in them. I can't find any identifying marks other than S6070 on a sticker on the backside of the boards. No one at the local club knew what they were either. Any ideas?

Frontside 

http://imageshack.us/photo/my-images/855/20110714104607.jpg/
Backside 

Also another strange thing is that when you slowly add voltage to the track, between 6v when the loco starts to move and about 12v the locos both roll about a foot then stop for a second or two and repeat this action until you get up to about 12v then they roll smooth including when you go back down too. This behavior only happens after a full power down of the track and voltage raise. Sound doesn't cut out when this happens, axles aren't bent or anything, it's something the sound module is doing. I don't think these are dcc boards but until I know what they are I don't know what I'm up against.


Thanks.

Brandon


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## Greg Elmassian (Jan 3, 2008)

Actually, looks like it is a DCC decoder too. Large transistors and motor outputs. That would also explain weird operation on DC, because early DCC decoders did not always do a good job on DC, and I'll bet your "DC" pack is not filtered DC, that can also produce these symptoms. 

Looks like the big number is the date code: 20071105, november 5, 2007, which matches the big transistors, and the Acc outputs, besides the lights... 

I'd guess an early MRC DCC unit. Does the sound come on? 

Greg


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## Brandon (Jul 6, 2011)

Yes, sound comes on, engine sounds ramp up as throttle increases, when train stops brake sounds are applied. Google images knowing it's an mrc points to the mrc 1817 o/g scale dcc module. 

Since I'm not doing dcc would it be best to take it out or is it safe to use it with a generic transformer? Generic being that I'm using a tech II 2500 right now but my bridgewerks 751 will be here in 2 days, is that filtered and would work better?


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## blueregal (Jan 3, 2008)

When you google the number on the backside, it comes up to Specktrum ????? Regal


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## Greg Elmassian (Jan 3, 2008)

MRC 1817:










Sure looks like it...

MRC decoders have a poor reputation, and especially on DC. My opinion: I'd dump it and get a $50 sound system or better.

I assume you are running DC?

You could also run it until it fails, but sometimes they really smoke.... Both George Schreyer and I have had catastrophic failures with various MRC DCC decoders, not this model in particular though.

Regards, Greg


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## Dan Pierce (Jan 2, 2008)

MRC 1818 and 1819 are the same layout. 

I have 1 of each and they come with multiple engine sounds and many bell/whistles/horn choices. Good for a box car to make them useable on different engines. 

And Greg is correct in that these have a 21 volt max rating and do not perform well on DC. 

MRC states these are NMRA compatible, but voltage rating and DC compliance are not there for me.


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## Brandon (Jul 6, 2011)

Is it possible to rewire the engine back to regular track power (no MRC module between the track power and motors) but wire the inputs to the MRC module so that it still produces sound and maybe still controls the lights? Or for proper sound production does the MRC module need to be hooked to the motors to detect load or other aspects to know if it needs to make it sound like the engine is working harder? 

Thanks.


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## Greg Elmassian (Jan 3, 2008)

Sure, you can do that, but why? You have a poor DCC decoder, that apparently runs worse on DC... Use diodes to control your headlight, run on DC, and you can use the board until it craps out. 


Greg


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## Brandon (Jul 6, 2011)

The problem using the MRC DCC decoder as-is is that it's built to run at a higher minimum voltage, Any lower than about 7volts and the decoder shuts off and it has to 'start up' the loco again which takes about 10 seconds. I have to put my 15A bridgework transformer at about 10v-12v when the motors are about to be started so the amp draw/voltage drop when the motors engage don't drop the track voltage below 7v (which restarts the decoder). Going from a dead stop to 10v-12v isn't exactly a smooth start and it makes it impossible to run the loco in a consist with my other loco's. Hence why I'd like to run the motors directly off track and only use the decoder for sound primarily... But I'm not sure if the decoder monitors amp draw from the motor leads to determine what sound it should be producing.


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