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Your advice please - Powered speaker blow just resting no music playing ...

abcmastra

Dec 14, 2015
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First ... im french, sorry for english.
Second, i'm 20 year experience DJ, i know everything about bad signal, distortion, amp power vs speaker power ... etc.
All balanced wire was used, the kit run flawlessly since 2006.

One of my dj speaker blow just resting. No music was playing.
All the rest of the kit is good ... not thinking about electricity fluctuation.

Where talking about a dj board connect direct into powered speaker, signal cable was plugged, decibel at normal zero position (100%) and no music playing.
Speaker was left there and open for 2 hours after being use normaly, no beating.

I'm scared to replace the speaker with a new one because of a defective amp that will kill the new speaker again.
Your opinion please, here more facts ...


Speaker made a humming loud buzz for 2 minutes and cooked.
Speaker smell burned, confirmed coil jam, not moving freely anymore.
Blowned fuse in amp inside the cabitnet, slow blow fuse T6.3L 250 volts

the equipement is Mackie SRM450 version 1 ... Real Italian original ... not the USA v2, not the china v3.
Speaker is a m1263w .. RCF build it i think.
The amp board have no number on it ... no smell ... just a blown fuse.

My theory .... the amp is defective and made the speaker moving silently (oscillation). Eat builded up, the coil
overheat and solder ... the amp tried to still make it move and the loud noise start ... the amp quit after 2 minutes a blow a fuse ...

My question, is changing the speaker will solved the problem, could the amp be fine ... can a speaker blow just resting not playing music ??

Thanks in advance for your experience ...
 

davenn

Moderator
Sep 5, 2009
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My theory .... the amp is defective and made the speaker moving silently (oscillation). Eat builded up, the coil
overheat and solder ... the amp tried to still make it move and the loud noise start ... the amp quit after 2 minutes a blow a fuse ...

My question, is changing the speaker will solved the problem, could the amp be fine ... can a speaker blow just resting not playing music ??

hi there
welcome to EP :)

your theory is pretty sound, specially considering the fuse blew. Time to so some diagnosing on the amplifier, starting at the PSU and moving forward into the amp
hopefully you can unplug the amp board from the PSU board ( assuming they are separate boards) else a little trickier ;)

get some photos posted so we all can see what we are dealing with

cheers
Dave
 

abcmastra

Dec 14, 2015
9
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Dec 14, 2015
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Dont waste your life on this .... just tell me if you think the amp is defective and bying another speaker is useless ..

thank you in advance ...

here photos
 

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abcmastra

Dec 14, 2015
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Dec 14, 2015
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Cause the amp board is no longer available ... so ... another speaker is my only chance.
 

KJ6EAD

Aug 13, 2011
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The amp is 12 years old and has electrolytic filter capacitors sitting right next to power transistors and power resistors. There's a slight possibility that replacing those filter caps and the fuse would repair the amp.
 

GPG

Sep 18, 2015
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Sep 18, 2015
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I think its likely a power transistor failure putting DC on the speaker. Replace fuse and turn on with no speaker and measure the voltage across the speaker leads, Sorry not much of a manual. Its Class G amp,
 

abcmastra

Dec 14, 2015
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Dec 14, 2015
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1- monday morning, i found some fuse .. waiting for the store to open

2- I will try this (Replace fuse and turn on with no speaker and measure the voltage across the speaker leads) but i have to google how to do it with a cheap multimeter - see photo

3- if not working, i bring the amp to repair shop to try this if not too expensive: (The amp is 12 years old and has electrolytic filter capacitors sitting right next to power transistors and power resistors. There's a slight possibility that replacing those filter caps and the fuse would repair the amp)

thank you all ... i let you know ...
 

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abcmastra

Dec 14, 2015
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Well ... the case will close fast .... as soon i put the amp on ... the fuse blow.

Its the same fuse, no signal cable plug, no speaker attach to amp into the cabinet.
It will be impossible for me to test with multimeter, the amp is short somewhere.

That solved the question of bying a new speaker ... it will not be neccassary, the amp is no more available so ... carbage !

thank you all for your time.

Does that means the other cabinet will blow too ? After 9 years of service ... 2006 ?
 

Tha fios agaibh

Aug 11, 2014
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I think CPG is probably right that a power transistor is likely bad.(shorted)
I would look into having it serviced before throwing it away.
Might be best to have the other cabinet overhauled too. Same age and usage means its likely to fail next.
 

abcmastra

Dec 14, 2015
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If you know a reliable tech, not too expensive near Montreal - Quebec - Canada ... let me know ...

thanks
 

Tha fios agaibh

Aug 11, 2014
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Of course, the kind folks here would be happy to walk you through the repair provided your comfortable tackling it.
 

abcmastra

Dec 14, 2015
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Dec 14, 2015
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im new to this forum ... how i do a search buy region and recomandation ? sorry for spelling ... im french
 

Martaine2005

May 12, 2015
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First thing to check if speaker is disconnected is output transistors..
Sometimes you can be brutal and snip the transistor out of circuit and try again..
If the short suddenly disappears and no fuse pops, that's your culprit..

Martin
 

Tha fios agaibh

Aug 11, 2014
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First thing to check if speaker is disconnected is output transistors..
Sometimes you can be brutal and snip the transistor out of circuit and try again..
If the short suddenly disappears and no fuse pops, that's your culprit..
Martin

And if it does pop, you probably just ruined a perfectly good transistor. Lol

I hear you though Martin. I suppose the chance that a component after the finals has shorted is rather remote.
I would think this technique would be left as a last resort.
 

Martaine2005

May 12, 2015
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OK, snip was wrong lol..Take out of circuit would have been a better way of saying it....
But my Stella Artoi fingers are typing now!!!!!
I can fix the world!!!
Cheers....John!!
 
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