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DCC Sound/Speaker Problem

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  • Member since
    February 2011
  • 7 posts
DCC Sound/Speaker Problem
Posted by sdlink on Friday, March 15, 2013 11:31 PM

Hey everyone, I am hoping you can help me with a problem I am having.  This week I installed my first ever Soundtraxx Tsunami decoder into a locomotive and at first things went well, now I am having an issue.  Here is my setup:

Atlas GP40 Locomotive

Soundtraxx Tsunami  TSU-AT1000 EMD 645 Decoder

QSI Speaker

I hardwired everything and everything worked beautifully, I had lighting control, speed & direction control, and all the sounds and it sounded great!  The only problem was i accidentally put the decoder in the wrong way so the directions were backwards.

I took the decoder out and flipped it around reinstalled everything put it on the track and at first the speaker started working like normal making the engine startup sound and then it kind of shorted out and stopped working.  Lighting still works, moves forward fine, but when I put it in reverse I get a lot of humming and distortion thru the speaker.  It still moves in reverse fine but weird distortion thru the speaker, and the sound functions no longer work.  I tried reversing the polarity of the speaker wires and this did nothing.

I took the speaker our altogether and the lighting and forward/reverse worked great.  Tried putting the speaker back in and forward works fine, but when I put it in reverse it starts buzzing again thru the speaker.

Anyone have any idea what is going on?  And why does this happen only in reverse?  The only thing I can think of is when I was soldering the wires back onto the speaker my soldering iron accidentally touched the back of the speaker and may have melted it a little.  It seems like the speaker has shorted out but why does it only buzz when I put it in reverse?

Any help would be greatly appreciated!

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Posted by mlehman on Saturday, March 16, 2013 4:16 AM

Does sound odd. Have you tried a full reset and then reprogramed it?

If the speaker cone was affected by the burn, I'd think it wouldn't matter which direction you're going.

Mike Lehman

Urbana, IL

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Posted by zstripe on Saturday, March 16, 2013 4:29 AM

I don't believe it is the speaker at all.. I believe something is up with the decoder...

Cheers,

Frank

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
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Posted by cacole on Saturday, March 16, 2013 8:06 AM

zstripe

I don't believe it is the speaker at all.. I believe something is up with the decoder...

I agree that it is something with the decoder and not the speaker.  If it were the speaker the problem would be the same in both directions with or without lights on.

Try a decoder reset (CV 8 =8 on the programming track).  If this doesn't solve the problem, contact SoundTraxx and see what they say.  The decoder can be sent back to them for repair if necessary.

Did you solder all the connections, or use those plastic clips to hold wires into position?  If you used plastic clips, remove them and solder the connections, being careful that two adjacent wires are not touching each other.

If you soldered the connections, unsoldered, and then resoldered them when you turned the decoder around, you may have overheated and damaged the decoder.

Your comment that the speaker "kind of shorted out" is the major clue here that you damaged the decoder, and it may need to be sent to SoundTraxx for repair.

  • Member since
    February 2011
  • 7 posts
Posted by sdlink on Saturday, March 16, 2013 12:11 PM

Thanks for the responses guys.

Here are some fixes I tried:
I bought a cheap small speaker from radio shack to test to see if it was just the speaker that was damaged. I wired this speaker and the result was there was no buzzing coming from the speaker in reverse like before, but the sound functions still did not work. Directional movement and lights still work but just no sound.

I also put black electrical tape over most of the bottom of the decoder and also covering the motor tabs/wires. (I think the negative motor wire/tab may have come in contact with the bottom of the decoder, not sure, but it could have.)

All the connections are soldered and soldered pretty well.  I did try reset CV8 to 8 and that didn't help either.

I am really confused on this. It was working perfectly when I had the decoder in backwards (so basically the FWD arrow on the decoder was pointing to the rear of the loco.)

Is it possible that only the sound portion of the decoder was damaged and everything else works fine??

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
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Posted by cacole on Saturday, March 16, 2013 6:44 PM

sdlink

Is it possible that only the sound portion of the decoder was damaged and everything else works fine??

Yes, it's entirely possible that when the speaker shorted out it destroyed the sound amplifier chip on the decoder.
If resetting the decoder did not cure the problem, then it seem pretty obvious that the sound amplifier is toast.  You need to contact SoundTraxx customer support and see if they think it can be repaired.
We had a similar problem at our club when a speaker wire touched a live rail when a decoder was being tested before connecting the speaker, which burned out the sound amplifier chip on the decoder.
  • Member since
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  • From: East central Missouri
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Posted by Santa Fe all the way! on Sunday, March 17, 2013 6:30 PM
I think you've gotten great advice, one other thing to check, make sure you didn't get some solder that has bridged between two tabs.
Come on CMW, make a '41-'46 Chevy school bus!
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Posted by kbkchooch on Sunday, March 17, 2013 8:54 PM

sdlink

All the connections are soldered and soldered pretty well.  I did try reset CV8 to 8 and that didn't help either.

Some Soundtraxx decoders take more that simply resetting the decoder. If you simply change cv 8 to 8, you must then kill the power to the unit for 10-15 seconds, upon restoring power the headlights will flash several times until decoder completed the internal reset. At that point the decoder is reset.

Simply resetting the cv it wont complete the action til the power is killed. If you try to throttle the engine, the decoder will simply ignore the reset request.

Yes, it is possible to damage only the sound portion of a decoder also, or the lighting portion, or the motor drivers only.  

My guess is somehow the magic smoke got out.

Karl

NCE über alles! Thumbs Up

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    January 2010
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Posted by zstripe on Monday, March 18, 2013 5:18 AM

sdlink,

I don't want to sound like a bad guy or anything, BUT if it is indeed a problem with the amp section,( which I believe it is.) There is no way they are going to be able to repair it... How will they be able to open it   up to do so?? It will probably go in the trash and be replaced, hopefully not at your expense..I would call them to find out...

Good Luck to You!!

Frank

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Monday, March 18, 2013 11:03 AM

zstripe

sdlink,

There is no way they are going to be able to repair it... How will they be able to open it up to do so??

I'm sure SoundTraxx has the equipment, expertise, and ability to remove the shrink wrap and replace surface mount devices on their decoders.  Train Control Systems and others can also repair their decoders.

  • Member since
    March 2007
  • From: South Carolina
  • 1,719 posts
Posted by Train Modeler on Monday, March 18, 2013 11:06 AM

I've had this happen before and have some suggestions/ideas

1. Your preamp/amp is likely blown--call Soundtraxx, send it back under warranty and they'll fix it pretty quickly.

2. For those chipsets with wired capacitor, put some tape on the end of it since it can cause a short in that area.  I'm embarrassed to say I had to learn the hard way on this--lol.

3. You could have changed CV29 for running normally reversed vs reinstalling the chipset.

Richard

  • Member since
    December 2004
  • From: Pa.
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Posted by DigitalGriffin on Monday, March 18, 2013 11:29 AM

Soundtraxx is good with their warranty.  Just send it back with the receipt AFTER you contact them AND filled out the form with the returned chip.  They will get you fixed up right quick.

 

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

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