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Discussion Starter · #1 ·
I don't have any idea what caused this. does anyone have any ideas. it was a sony sa-wm40 12" sub. I have had it for about a year and a half.

I was just watching a movie when it went.
 

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Good luck. My SA-WM40 lasted 60 days. I was watching The Screen Savers one evening and it went into standby mode. It never came out.


To make a VERY long story short I finally got my money back from Sears. I promptly bought an SVS. I couldn't possibly be happier with it and their customer service is far superior to any company I have experienced in any field.


As for your Sony I really have no idea. Voice coil or amp, maybe?
 

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Where is the smoke coming from? You could have burned out the voice coil.
 

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Quote:
does anyone have any ideas.
Dont mean to be a smarta** but just get a new sub. I cant see those subs as a whole lot of money so maybe its time to invest in a better sub if you listen to your system alot.
 

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Discussion Starter · #5 ·
Quote:
Originally posted by Yosh70
Dont mean to be a smarta** but just get a new sub. I cant see those subs as a whole lot of money so maybe its time to invest in a better sub if you listen to your system alot.
I was asking if anyone had any ideas as to what could have caused the sub to do what it did.
 

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Smoke will generally come from the voicecoil overheating on the speaker itself. This is usually due to clipping because there is not enough reserve power in the amp. I know, it doesnt sound at first like it makes sense, but a blown speaker that smokes is usually caused by not enough power. The wavefrom clips at the top of the signal and the speaker sees that as DC voltage, which causes the coil to heat up. Once it starts to heat, the coil and former that it is on will swell and eventually it will rub against the magnet assembly, then once it wears through the insulator on the copper windings: sparks, lightshow, bad smell, at that good stuff. Sorry, dude, but your sub is probably a write-off, no chance in saving it once it smokes. You could try putting a different driver in the enclosure, but you are better off replacing the whole unit.


I guess a power spike or some other problem with the A/C source could be the culprit as well, but mostly its too little power.
 

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I've done the low cost sub thing (Sony SA-WM40 and Cerwin Vega LW-12). As hard as it may be I'd keep saving until you can get something like a HSU, Adire Rava, or an SVS. I'm talking $400-600. I am a VERY pleased SVS owner that spent under $600.


Don't take my word for it though. As a starting point do a search for the brands I listed above. Those threads will lead you to the folks I left out. Good luck, I hope you are back up and running before long.
 

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Big pop and smoking burning. Time for Sherlock...

It's probably _not_ the driver. If the smell is an acrid, crinkly in the back-o-the-nose smell, it's likely to be the transformer. If it's a dampish, used diapery smell, it's likely to be a large capacitor, if it's a burnt metallic/plastic smell, suspect a semiconductor: output transistors/ module or rectifier diodes, and if it's a rank burnt glue smell, the PCB is shot as well.



The pop sound- if accompanied by a loud hum, suspect the rectifier or capacitors. If _no_ hum, but more of a gunshot sound, it's the output stages. Transformer failure is usually just instant silence, unless the primary shorts to the secondary, and all hell breaks loose inside.


BTW, it's not worth fixing.
 

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it's always so hard to get electronics to work again once you release the magic smoke.


We had this theory in college, back when we were experimenting with screwdrivers, soldering irons, and power supplies, that electronics manufacturers had somehow managed to capture the magic smoke, put it into the components, and it would spend the rest of its days trying to get free. I did not do so well in my physics classes.
 

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I don't know about the two being necessarily related (smoke generation ability being inversely proportional to physics results).


I knew someone who thought the height of entertainment was connecting capacitors to mains AC in his fathers garage. He worked all the way up to a monster 1F capacitor (back then - late 80's - you could get them out of old VCRs, as they used them for memory backup). This short career in magic smoke experimentation was cut short when he blew a fair sized hole in the floor (after releasing a quite impressive amount of said smoke).


It didn't stop him eventually getting a good physics degree though. Ergo, I don't know if the two are related, although the sample size is small...


;)
 

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Quote:
Originally posted by apg
Big pop and smoking burning. Time for Sherlock...

It's probably _not_ the driver. If the smell is an acrid, crinkly in the back-o-the-nose smell, it's likely to be the transformer. If it's a dampish, used diapery smell, it's likely to be a large capacitor, if it's a burnt metallic/plastic smell, suspect a semiconductor: output transistors/ module or rectifier diodes, and if it's a rank burnt glue smell, the PCB is shot as well.


AGP, I believe you have spent entirely too much time sniffing things.... :D
 

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APG may be one of those lucky few that can be sniff testers for various fragrances. I wonder if some manufacturers might keep them around to give exactly the kind of debugging information. "Ahh, a diapery smell, check capacitor a-27"
 

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Although I have a fair amount of test equipment, on occasion, I have had to use somewhat more primitive methods. A friend had a Sherwood amp that blew the main fuse. I hooked it up to a variac, ran it up to where it drew a couple of amps, and felt around the chassis. On one channel, one output transistor was warm, as well as one driver transistor. These were the _good_ transistors. The complementary ones were cold, therefore, they were shorted out. I replaced those, and the Sherwood powered up just fine.


On a Heathkit shortwave receiver with no audio, the cathode resistor on the output tube had a small crack in it- We replaced the overheated resistor, and the tube with a heater to cathode short, with new ones, and the Heathkit flew again.


A good tech uses all their senses, not just the ones that require electronic augmentation.


Then there was the time I was working on a sick Ferrari V12, and I noticed a hissing noise coming from the........
 

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Quote:
Originally posted by apg
Big pop and smoking burning. Time for Sherlock...

It's probably _not_ the driver. If the smell is an acrid, crinkly in the back-o-the-nose smell, it's likely to be the transformer. If it's a dampish, used diapery smell, it's likely to be a large capacitor, if it's a burnt metallic/plastic smell, suspect a semiconductor: output transistors/ module or rectifier diodes, and if it's a rank burnt glue smell, the PCB is shot as well.



The pop sound- if accompanied by a loud hum, suspect the rectifier or capacitors. If _no_ hum, but more of a gunshot sound, it's the output stages. Transformer failure is usually just instant silence, unless the primary shorts to the secondary, and all hell breaks loose inside.


BTW, it's not worth fixing.
apg,


Absolutely without a doubt the best failed electronics sleuthing descriptives I have ever read. It brought tears to my eyes as I recalled encountering those smells over the years, never knowing what had gone wrong. Thank you!


David
 
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