Creative A520 Speaker, burnt power supply in lightning

[Alexandre Neves Lopes]

Guys! please! I really need a return here.

 

[xTatshx]

BT9843

 

[Abinoh]

Bro its BT9843
Audio Power Amplifier IC

 

[Alexandre Neves Lopes]

Thanks to xTatshx and to Abinoh. You both are the best! Thank you.

 

[Santhuchary]

The power supply of my Creative A520 speaker system got nuked in lightning. I tried an external adapter 12V/1Amp and it works with occasional volume loss during heavy bass. I guess the adapter is unable to supply enough current.
I am trying to repair the power supply but cannot figure out the values of the burnt parts.

I can see two resistors and a zener diode as burnt:

Please help me figure it out.View attachment 94210

 

[Santhuchary]

Hi bro,
Same issue on my creative A520 speakers...but a had a doubt that what is the o/p voltage of power board...as you above figure power board..reply me back dear..!!

 

[Abinoh]

Santhuchary
The o/p is 12v 5A

 

[stealthjoe]

I' ve used 12Vdc 5Amp SMPS(Commonly found on CCTV systems) to supply the Unit and It sounds Fine without cracking the sound, even i Tune to its maximum Volume no cut offs.

Hi xTatshx,
I have the same creative speakers make and it stopped working recently after a power outage (no power input). Hence, I recently ordered a new 12v 5a smps.
My clarification is whether the main power cord goes to the L and N of the smps. Next I need to know whether the output of the bridge rectifier in the amplifier circuit which has the twisted wire(having ac inputs) is the one that goes to the +v and - v of the smps. Please clarify as I am quite a noob at this. Thanks and awaiting your reply.
Regards,
Joe

 

[stealthjoe]

Could anyone please help me with the above query!!

 

[audioguru]

The creative A520 speaker system is spec'd to produce 12W into its little (sub) woofer and 5W for each little satellite speaker but the distortion is not stated. It is probably clipping like mad so that its total is 37 distorted Whats or 30 Watts with reasonably low distortion. Then a 12V power supply should be rated for 30/12= 2.5A.

Of course the little woofer with its low power amplifier cannot produce heavy bass.

 

[rjenkinsgb]

Then a 12V power supply should be rated for 30/12= 2.5A.

That would require the amps to be 100% efficient and no other power overheads?? Surely figures like that are only used in dodgy advertising

A 12V 5A supply is fine, if that's what was originally used, go with it - or if the original was rated at a lower current it will not do any harm.

[I don't have that speaker system so cannot help with internal wiring, sorry].

 

[audioguru]

Does anybody play a sound system with continuous sinewaves on all channels at full blast? Music and voices produce an average loud output power of 1/5th to 1/10th the rated low distortion RMS power.

I have a similar Sylvania sound system as this Creative one. Its woofer is the same size but it has only two satellite speakers, not 5 of them. It is rated total output power is 150 Watts or 75W RMS. But its small power transformer is labelled 9VAC/1.1A (9.9W). Its little amplifiers are linear, not class-D so they use some power producing heat. I figure that its woofer gets 4 to 5 real Watts and its satellites get 1.5 to 2 real Watts each. It produces plenty of good sounds.

 

[stealthjoe]

[I don't have that speaker system so cannot help with internal wiring, sorry].

Sure. No problem, but just checking if the DC output from the power supply into the amplifier circuit enters through a full wave bridge rectifier (W10 in my case) for a typical surround/sub woofer system.
If this is the case in most subwoofer amplifiers, does the polarity of the dc output into the rectifier matter?

 

[Nigel Goodwin]

I have a similar Sylvania sound system as this Creative one. Its woofer is the same size but it has only two satellite speakers, not 5 of them. It is rated total output power is 150 Watts or 75W RMS.

Except it's not - the made up specification might 'claim' such imaginary values, but it's certainly not 'rated' at that

 

[stealthjoe]

Update:

I got the SMPS (12V 5A) and plugged it to my amplifier. First I wasn't getting any output on my speakers. Tried adjusting the smps dc output wires and then was getting some weird loud noise in addition to the speaker sounds for sometime. I tested the DC current by putting my multi-meter red probe to the red 10A socket. The current reading was showing as 0.30 (measured it in series by connecting one dc output to the multimeter). Shouldn't it be 5A?
After a while, the static noise stopped completely and all the speakers were outputting as expected. Tested this way for a few hours and not getting any static noise after that. One concern is that my bass is weak. If I hold the bass adjustment knob tightly, the bass increases. If I leave it, the bass is back to weak again. Few clarifications now:

1) Wanted to know if the static noise in the speakers will return again and if so what is causing this?
2) Any tweaks to make the bass sound more stronger?
3) My DC current reading is showing as 0.3 on the multimeter whereas the smps current rating is 5A. Am I making some mistake in measuring the current?

Appreciate if someone could give their insights on the above.

Regards,
Joe

 

[audioguru]

A few amplifiers are "class-A" and are actually room heaters and they draw maximum power supply current all the time. The Creative amplifiers and most other amplifiers are class-AB or class-D that draw only as much current as the output power needs. Your Creative speaker system is rated at 37 Whats when it is blasting severe distortion louder that it can play normally. That is 37/12= 3.1A. It would draw 0.3A when not playing loudly.

We do not know what is causing your static noise or if it will happen again.
It sounds like your bass control is worn out and needs a replacement. The small woofer and low amplifier power does not produce much bass anyway.

 

[stealthjoe]

A few amplifiers are "class-A" and are actually room heaters and they draw maximum power supply current all the time. The Creative amplifiers and most other amplifiers are class-AB or class-D that draw only as much current as the output power needs. Your Creative speaker system is rated at 37 Whats when it is blasting severe distortion louder that it can play normally. That is 37/12= 3.1A. It would draw 0.3A when not playing loudly.

We do not know what is causing your static noise or if it will happen again.
It sounds like your bass control is worn out and needs a replacement. The small woofer and low amplifier power does not produce much bass anyway.

Thanks for your reply audioguru. Few more clarifications.

1) At times, the bass seems to be fine. However, when I play a moderate to heavy bass song or video to test it, I can notice the sub crackling a bit intermittently. Could it be related to the SMPS I recently installed or is to do with something else? Let me know.

2) Any suggestions/tutorials on how to replace the bass knob as the ones I searched on youtube were mostly related to car audio systems?

Thanks.

Regards,
Joe

 

[audioguru]

Crackling could be the little woofer has its voice coil hitting the magnet structure, or is the amplifier clipping because the volume control setting is too high.
I doubt you will find a replacement bass control that will fit.

 

[stealthjoe]

Thanks audioguru. I have made some audio adjustments by installing Equalizer APO . Have increased the treble gain and frequency in addition to the bass settings. Now the audio seems pretty good.

 

[audioguru]

Are you one of the kids on my street who go to school on their electric skateboard with a pretty-good-sounding sound system in their backpack?