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MRC sound decoder?

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MRC sound decoder?
Posted by Rotorranch on Wednesday, January 30, 2008 7:20 PM

I'm putting an MRC sound decoder in an Athearn AMD103.

Is it a direct plug in?

Do I need to change the light bulbs?

What is the voltage of the decoder light output?

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Tilden on Wednesday, January 30, 2008 10:30 PM

Whether or not it is a direct plug-in depends on the decoder and if the engine has an eight or nine pin plug.  The light output On MRC decoders is usually about 12 volts.  However, some decoders, like the 1634, have three light hook-ups.  One for 1.5 volt, one for 12 volt and one for LED's. 

If the engine has a DCC plug and the decoder has a plug you normally don't have to change bulbs.  You never really have to change bulbs but you may need to add a resistor in the lighting circuit if the decoder light output is higher than the bulb rating.

Tilden 

 

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Posted by Rotorranch on Wednesday, January 30, 2008 11:06 PM

The decoder is has an 8 pin plug. It's an MRC AD370 sound decoder. Of course, the instructions are a little lacking. And I'm sure I'll be disappointed, after getting my first ever sound locos, an E-6 P2K w/QSI, and a Spectrum 2-8-8-2 . But I've had 3 of them for about a year before I got the the sound locos. Plus I got a deal on them! Can't take them back now! Big Smile [:D]

It looks like the Athearn circuit board has a jumper board that you remove, then plug the decoder directly into it, not using the 8 pin plug harness.

I've not had the shell off the Athearn unit yet. Just broke it in last night.

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Rotorranch on Thursday, January 31, 2008 12:50 AM
 davidmbedard wrote:

If you want to use the 8-pin plug in the Athearn unit, then you have to remove the jumper board from the 9-pin plug.  Just an FYI

David B

That's all? No light changes?

I still don't see a "9 pin plug".

I counted several times, and my decoders have 10 pins. The DCC plug has 8 pins.

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by jamnest on Thursday, January 31, 2008 8:55 AM

I have not purchased any MRC sound decoders as I am informed that the sound volume can not be adjusted.  Has this problem been corrected?

JIM

Jim, Modeling the Kansas City Southern Lines in HO scale.

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Posted by wjstix on Thursday, January 31, 2008 10:34 AM
 Rotorranch wrote:
 davidmbedard wrote:

If you want to use the 8-pin plug in the Athearn unit, then you have to remove the jumper board from the 9-pin plug.  Just an FYI

David B

That's all? No light changes?

I still don't see a "9 pin plug".

I counted several times, and my decoders have 10 pins. The DCC plug has 8 pins.

Rotor

I believe the MRC decoders are nine-pin decoders, but come with an attached harness (usually about 3-4" long) that converts the nine-pin to an eight-pin plug for "plug and play" installation. Most engines come with a light board with an eight-pin receptacle with a dummy plug in it, you remove the dummy plug and plug in the decoder using it's eight-pin plug.

It may be that in some engines you have some sort of dummy plug connected to a nine-pin receptacle?? In that case, you'd need to remove the 9-pin to 8-pin harness from your decoder and plug the decoder into the light board that using the 9-pin connection.

Stix
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Posted by Tilden on Thursday, January 31, 2008 11:39 AM

Rotor,

  An AD370 eh?  David is being unusually kind regarding MRC decoders.  Ok, the AD370 is a "first Generation" sound decoder.  To say it is basic, is being kind.  It is fairly large and has only four sounds (bell, short horn, long horn and conductor (all aboard)). None of these sounds are particularily good, some may say harsh.  In addition, it has an engine sound of unknown origin (MRC says its an Alco).  The volume tends to be a bit loud and motor control is not the best.  I have replaced most of my 370's or don't run them much.  It has the standard  eight(8) pin NMRA plug. 

  Now, the loco.  If it is a newer RTR model, the light board will have both the Nine(9) pin JST (long flat) plug and the eight(8) pin plug.  All you have to do is plug the decoder in with the orange wire in the #1 pin slot (if you reverse this, the loco direction is reversed).  If you are looking at the board from behind, with the front of the loco pointing away from you, the #1 pin is the upper right one.  As mentioned, you have to remove the jumper board from the JST plug.  No adjustments for the lights are necessary.

  If the loco is an older RTR version, it will have the 9 pin JST plug and the slots (but not the recepticle) for an eight pin plug.  In this case, you will have to A:  insert the eight pin plug and solder the individual pins into the light board (not for the faint of heart or those lacking good soldering tools and skills). or B:  remove the eight pin plug and solder the leads of the decoder onto a JST recepticle.  (if you have those good soldering skills you could use the jumper board, but it ain't easy)  I've done both, B is the better option and buying a wired recpticle to attach the decoder to is the best way to go.

Good Luck

Tilden

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Posted by Anonymous on Thursday, January 31, 2008 11:48 AM

Why are we getting MRC junk when quality decoders with fine pedigrees like NCE, Digitrax etc are out there and availible?

I agree that David is being very kind today.

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Posted by BlueHillsCPR on Thursday, January 31, 2008 12:58 PM
 Falls Valley RR wrote:

Why are we getting MRC junk when quality decoders with fine pedigrees like NCE, Digitrax etc are out there and availible?

I agree that David is being very kind today.

Well...lets remember that not all of us are as savvy as the next guy...Smile [:)]

I nearly convinced myself to choose MRC for DCC before arriving at the MRR forum and learning otherwise.  Because of MRC's record in DC control it would be easy to be led down the "wrong" path.  Lets not jump on the OP too hard. Smile [:)] Thumbs Up [tup]

We're all learning together here. Cool [8D]

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Posted by Rotorranch on Thursday, January 31, 2008 1:43 PM

I had bought these a couple of years ago, on a blowout sale from the distributor. They cost less than the non-sound decoders!

I understand  that they aren't the best sound decoders out there, but I have them, so I might as well use them. As I said earlier, I'm sure I'll be disappointed, compared to my P2K's w/QSI.

According to the box, the sounds are Bell, long horn, short horn, coupling, Diesel Idle and Diesel Rumble.

Thanks for the info folks. I guess I'll plug one in and try it this evening. Smile [:)]

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Tilden on Thursday, January 31, 2008 1:47 PM

  The MRC Prodigy Advance DCC system is good.  It's easy to understand and use and is more than adequate for most home layouts, even large ones.

Tilden

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Posted by Rotorranch on Thursday, January 31, 2008 5:22 PM

Well, that didn't work. Sad [:(]

The Athearn circuit board has an 8 pin socket, but no terminals. The MRC decoder plug fits, but just wallows around.

The Athearn board also has a 9 pin connector, with the jumper board.

The MRC decoder has a 10 pin plug on the decoder! The harness is an 8 to 10 pin harness.

I guess I'll just have to cut the 8 pin plug off the harness, and hardwire the harness to the circuit board.

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Tilden on Thursday, January 31, 2008 5:38 PM

Rotor,

  See my post above.  Depending on your soldering skills, you can leave the 8 pin plug on and solder it directly to the board.

  BTW, the socket on the AD370 is NOT compatable with a 9 Pin JST plug.

Tilden

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Posted by sabaj on Thursday, January 31, 2008 5:58 PM

Go to  and join MRC-DCC@ yahoogroups.com.  you can ask questions about MRC DCC and get answers from MRC users and there is one member who works at MRC and if he does not know the answer he goes a talks the the MRC TECHS and comes back. The president of MRC has been known to read the form too.

YOU DO NOT GET THIS YOU ARE A DUMB *** BECAUSE YOU BOUGHT A DIFFERENT PRODUCE THAN KNOW IT ALL ME.

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Posted by Rotorranch on Thursday, January 31, 2008 8:50 PM

I got it going. Big Smile [:D]

I ended up cutting the 8 pin plug off, and soldering direct to the holes in the board. The decoder is a little big. I actually had to mount it to the inside of the body at the rear; it was too large to sit on top of the stock PC board. I stood the speaker up vertically near the rear door.

I screwed up, and forgot to remove the jumper board...the decoder started hissing and melting the heat shrink on it. Pulled the jumper, and all is good. Approve [^]

Now I just have to turn the sound down some. It's a bit loud.

No, it doesn't sound as good as my P2k's, but for less than $20 bucks, it'll work!

We'll see how long it runs. Smile,Wink, & Grin [swg]

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Anonymous on Thursday, January 31, 2008 9:03 PM

If MRC puts in Back EMF on those decoders and give them a little more values to play with on the software level... I might want some.

Im glad you got yours running, but double check from time to time to make sure you are not slowly burning your decoder against something inside that engine.

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First Failure....
Posted by Rotorranch on Thursday, January 31, 2008 9:52 PM

OK...it just turned the sound down...by itself? Sigh [sigh]

I guess I let too much of the factory installed smoke out of the decoder! Whistling [:-^] It still ran ok, but the sound isn't right. The bell works, but no horn, and low engine noise.

Plugged another one in, and we'll see how long it goes.

I mounted this one on a .030 thick, 1 inch wide strip of Lexan attached with double sided R/C servo mount tape, running between the Athearn circuit board and the speaker at the rear, so it's not on the body now.

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Rotorranch on Thursday, January 31, 2008 10:06 PM

Well...the second decoder just did the same thing after running for about 10 minutes. A minute or so later, the sound come back on. So maybe there is nothing wrong with the first one? Might just be a glitch in the decoder?

I'll try the other decoder again tomorrow. Right now I'm going to grab a cold one, and run some trains. Smile,Wink, & Grin [swg]

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Rotorranch on Saturday, February 9, 2008 12:33 AM

Well it's still running, and its still loud. Smile [:)]

Power and controllability is ok. Sounds are somewhat lacking, but better than nothing. I've not changed any CV yet.

 Is it possible to change the CV for volume on the MRC decoders with a Digitrax Big Boy? I have no upgrades on the system. I figured I'd ask before I started chasing my tail.

Rotor

 Jake: How often does the train go by? Elwood: So often you won't even notice ...

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Posted by Tilden on Saturday, February 9, 2008 12:20 PM

The MRC AD370 has no volume control CV.  I have heard (but not tried) that putting a 15 ohm resistor in-line in one of the speaker leads will lower the volume to a "good" level.  I have one or two loco's that need this fix, even one's with programable volume control.

I once asked MRC why the sound was so loud.  They responded it was because they were all deaf.....

Tilden

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