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Frying Loksound Decoder

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  • Member since
    March 2013
  • From: Australia
  • 158 posts
Frying Loksound Decoder
Posted by tomcat on Friday, April 11, 2014 1:17 AM

Hi all wonderful people need your help once again

I have an australian Loco (82 Class) with a Loksound decoder in it and after a basic re solder of the front truck pick up wires when i repowered the loco on the track I got the Magic Blue Smoke and fried the sound decoder so naturally i thought i had shorted it out somehow, After triple checking it all i havent done that at all I just resoldered the pick up wire at one end, So I got my new decoder yesterday and when i put it in it fried again????

Hers the strange part I put a non sound TCS decoder in just so i can run it and it works fine , If there was a short somewhere am I right in thinking that it wouldnt run period??, So why is it frying the sound decoder and working fine with the non sound decoder. Am I missing something basic or is something more sinister going on here.

Thanks for any advice

  • Member since
    April 2004
  • From: Ontario Canada
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Posted by Mark R. on Friday, April 11, 2014 1:46 AM

What kind of Loksound decoder ? Hardwired or plug-in ? 

Just guessing here, but it sounds as though something moved or got pinched when you opened / closed your engine for the truck repair. Completely changing to a different type of decoder corrected the problem in the process. (?)

When you "fried" the decoder, was it completely dead ? No sound, no lights, no movement ?

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

  • Member since
    March 2013
  • From: Australia
  • 158 posts
Posted by tomcat on Friday, April 11, 2014 1:52 AM

Hi Mark

its a plug in type 21pin

The only sound that it made was a loud strange eerrrkkking sound then the blue smoke appeared so i took off the power straight away i didnt try proceeding anymore

Yes the TCS decoder allows it to run fine ,I did check thoroughly for pinched wires , i didnt see any and then i illiminated that problem when it worked with the TCS

  • Member since
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  • From: Jacksonville, FL
  • 913 posts
Posted by gatrhumpy on Friday, April 11, 2014 5:22 AM

Might need to get it professionally installed.

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Friday, April 11, 2014 7:40 AM

If your model has a built-in 21-pin MTC socket for a LokSound decoder, you may have caused a short when you performed your 'repair' and created a solder bridge or some excess solder got splattered onto the circuit board; a very easy mistake to make when dealing with printed circuits and not having the proper tools, especially a high-quality magnifier and very bright light, to check for such mistakes.

Substituting a TCS means you used either an 8-pin socket or a 9-pin JST socket instead of the 21-pin socket, thus eliminating a possibly mis-wired or shorted connection on the circuit board.

If you want sound, use the JST or 8-pin socket for a new LokSound decoder instead of the 21-pin socket and things should be okay.

Consider this a lesson learned -- don't try to perform your own repairs without the proper tools.

 

  • Member since
    March 2013
  • From: Australia
  • 158 posts
Posted by tomcat on Friday, April 11, 2014 8:26 AM

ok. The only thing that bugs me is I only soldered the wire to join it back on to the truck, due to my lack of experience i stayed right away from the pcb, thats whats so strange about the whole thing,

but I do get where your coming from

thank you

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Friday, April 11, 2014 5:11 PM

Well, if that's all you did, that should have no bearing on why the LokSound decoder was fried.  I think there's something else going on here; perhaps a headlight or backup light wire, or speaker wire, got pinched against metal as you were reassembling the model -- most likely a speaker wire, which would most definitely short out the amplifier and cause the release of magic smoke.

  • Member since
    July 2006
  • 3,312 posts
Posted by locoi1sa on Friday, April 11, 2014 6:44 PM

Tomcat.

 Try using the current limiting program track after any work done on a locomotive. Most decoders will survive a short on the program track. My power cab will tell me there is a short before any damage is done.

         Pete

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

  • Member since
    April 2004
  • From: Ontario Canada
  • 3,574 posts
Posted by Mark R. on Friday, April 11, 2014 9:12 PM

Tomcat - You still haven't answered my query .... when you "fried" the decoder, of the three aspects - sound / lights / movement, did ANY of them still work ?  If you blow the audio amp, the engine should still run and the lights should still work. Your answer to this would help to possibly narrow down the source.

 

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

  • Member since
    March 2013
  • From: Australia
  • 158 posts
Posted by tomcat on Saturday, April 12, 2014 12:03 AM

Mark

no nothing works, I just get that horrible errking sound out of the speaker , then as the smoke comes i take it off the track, but the engine runs fine with a non sound decoder (TCS)

BTW I did use the programming track to test it on after my repair and this is where it all went bad

  • Member since
    April 2004
  • From: Ontario Canada
  • 3,574 posts
Posted by Mark R. on Saturday, April 12, 2014 1:06 AM

If you lost everything, your short occurred somewhere between the wheels and the input diodes on the board. If it was a short in your speaker wires, you would still have lights and movement. If it was a short in your light wiring, you would still have sound and movement.

But if you had absolutely nothing, an inbound short to the decoder took it out.

Seeing as how TCS decoders don't use a 21-pin plug, how did you hook it in ? I'm thinking the problem is somewhere in the vicinity of the 21-pin socket and you've bypassed it with the TCS decoder.  If you can't find the problem with the plug, I'd suggest a hard wired Loksound decoder installed the same as the TCS decoder as it appears to be working as connected.

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Saturday, April 12, 2014 10:15 AM

tomcat

BTW I did use the programming track to test it on after my repair and this is where it all went bad

 
As soon as you exit "programming" mode and attempt to run a locomotive, even on a so-called Programming Track, you are applying full voltage to the model.  
 
The only way it could have begun to smoke on the programming track was if your DCC system was not in programming mode.  In programming mode, a short should have caused your DCC system to shut down instead of allowing voltage to be applied to the rail.
 
But at this point in time, we're all just guessing what the problem may have been since none of us can see and examine the model.
 
 

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