Creative SBS 370 – 2.1 Speaker Modifications
Received creative speakers stated problem both the satellite speakers Works intermittently when Vary Volume Control so that It is confirmed problem with the Volume Control. So I opened the external wired Volume Control Unit.
I didn’t find any dust or Physical damage hence Cleaned the 5 Pin potentiometer using IPA. But problem remain same. So decided to change the POT and see the result I am having 4 Pots in my stock I have replaced one but same problem.
For further diagnosis I have opened Woofer Unit (In this type of 2.1 speakers mostly amplifier circuit is located in woofer Unit).
Trying to remove the circuit from back side of the woofer unit but it was stuck somewhere inside.
So tried by removing Woofer to see what wrong inside is. I found Very Short length woofer Cable is connected to the Circuit therefore circuit is not coming out from backside.
So desoldered the cable from woofer and pulled Circuit out from the back side. You can see large size of Heatsink is attached with main amplifier IC.
Circuit Used MC4558CN operational amplifier: https://www.alldatasheet.com/datasheet-pdf/pdf/23296/STMICROELECTRONICS/MC4558CN.html
TDA8510J 26W Power Amplifier:
For reconfirming doubt of bad volume control I have shorted two wires on volume control signal in & signal out on the PCB (Bypassing Volume control).
and connected the stereo pin in my mobile and played the song I got good loud sound without any disturbance concluded the problem with Volume control & I Removed remote Volume cables & connected external 10K Stereo Pot for final testing & it works Fine without problem.
I have tried replacing 5 pin volume control did not work. I thought because of old stock may be Pots are gone bad so I have purchased two new pots but none of them are worked tested all pots with multimeter all pots showing Ok condition.
Now problem is that remote unit does not having space, where I can put this big stereo pot and not finding place on the woofer box also well because woofer box is made of compressed cardboard if I make Hole by using drill it will damage the cardboard and also thickness of board is not permitting to do so.
I got an idea to install USB/FM/MP3/Bluetooth kit because it has wireless remote which solve my all problem in marginal price difference I have got this kit in price of two Volume controls. I have arranged this Kit from the market.
It works on 5VDC so decided to give him power from the board only & I found the point from where I can take power it is main filter capacitor where I am getting voltage through adapter of speaker.
Connected 7805 Regulator on mains Filter capacitor for 5V DC for operating Bluetooth kit.
Confirmed the working of the kit after applying voltages from 7805 regulator.
Now it is time for final fitting preparation. I have cut the one side of woofer box and as per my doubt about damaging cardboard. It was badly damaged while cutting with hacksaw blade but I have managed to fix it by applying some wood glue.
And kept the box overnight for curing it properly. Now time for preparation of modification on the amplifier PCB for adding this Kit. Connected external volume control wires from Bluetooth kit directly to the amplifier by removing old control wires.
I Putt Led in place of ON /Off switch for making direct connection by removing On/Off switch wires and putting this as a power indicator backside Near DC Jack of the Box.
R – Indicates right channel of Volume,
L- Indicates Left Channel of Volume and
Now after modification Speakers are ready with new additional options.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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