Pioneer S-RS3W 12inch powered subwoofer teardown

The Pioneer S-RS3W is a powered subwoofer with two ports that I purchased about 2 years ago for 

150 dollars (USD). It has a 12 inch woofer cone and is powered by a 180W RMS amplifier.

You can see the plastic cover cabinet that houses the amplifier unit at the rear of the subwoofer.

The back cover is held by 8 philips screws that come right off, exposing the amplifier board and the control board (the control board is still attached to the casing in this picture) .

At first glance the amplifier is bolted heavily onto a large metal plate that holds the entire parts list.

Beneath this metal plate is the subwoofer cabinet wood enclosure.

At the middle of the rear wooden cabinet is a hole whereby the speaker cable goes through and the status LED indicator of the subwoofer go through. More details on this later

Oh hope you noticed the fan screwed directly on the wooden enclosure. This cools the heatsink directly.

I unscrewed the PCB from the plastic enclosure to finally expose the input board and potentiometers.

This board is the JACK ASSY.

There are two RCA entries on the left. One is the signal INPUT and one the signal OUTPUT.

The input goes to an op amp buffer with unity gain that echoes the input to the second RCA port.

Signal goes from that op amp buffer into a phase select switch connected in series with the non inverting input of a secondary op amp that can reverse the phase of the input signal by 180 degrees

From there the signal goes to a Low Pass Filter section (basically a single opamp + potentiometer) connected to it allowing the user to adjust crossover frequency range from 50Hz to 200Hz. The potentiometer knob is visible on the rear of the device for manual adjustment of the cross over frequency.

The Low pass Filter (LPF) can be bypassed thereby allowing non filtered audio from the audio input to the amplifier using an external switch available on the rear of the device.

The JACK ASSY also features the main power switch that turns the unit on and off.

The signal leaves the JACK ASSY to arrive at the POWER AMP ASSY 

THE POWER AMP ASSY

There are only 3 boards on this unit one is the JACK ASSY, REGULATOR ASSY, POWER AMP ASSY.  In the picture above, the JACK ASSY is on the extreme right, the topmost board is the REGULATOR ASSY, the lowermost largest board is the POWER AMP BOARD.

REGULATOR ASSY

Two power regulators are present on the topmost PCB one is a +12V regulator and the other a -12V regulator.

The +12V and -12V rails along with a GND rail power all the op amps found on the PCB board. The voltage is combined to output 24V to the fan that cools the heat sink of the amplifier board. 

The fan has a positive and negative lead as well as a fan control lead (for RPM adjustment)

POWER AMP ASSY 

There are two 5600 uF capacitors on the left side of the board (nichicon brand) the output of which is rectified by a non heatsinked bridge rectifier.  The operating voltage output of the rectifier is +/- 62 V according to the schematics

POWER AMPLIFIER IC  - STK404 140N-E

The amplifier hybrid IC powering this unit is called GODZILLA by Pioneer (insane..) It can produce 180W RMS into 6 ohm load. 

THERMAL REGULATION

One thing that puzzled me was the mere absence of thermistors and the like mounted on the heatsink! Turns out the Amplifier Chip has got an internal thermal sensor that is actively measured by transistor logic circuits that in turn adjust fan speed! The following picture is that from the IC datasheet

This picture below is the same datasheet technique applied by pioneer engineers

Mercedes Benz W203 C 180 Kompressor SRS Failure

I am finally having time to write about this issue that I faced about a month or so ago and how I got around it.

One morning I started my car and realised both my wipers, my horn and my SRS airbag system had failed all at once! Imagine the nightmare..

Thankfully no other errors showed up but I essentially went straight to my garagist who works at Iframac (local mercedes service centre mauritius). From his initial tests using the STAR diagnosis (software that runs on a laptop which is in turn connected by a cable to the car computer)

After several hours of troubleshooting the STAR diagnosis software estimated that the SAM unit had failed. SAM stands for Signal Acquisition Module basically a circuit board located under the bonnet that deals with sensor readings and actuating motors etc in the front of the car

Realising that such a unit costs Rs 14 000 local mauritian rupees, (205 dollars USD) I decided not to be in a haste and investigate the matter further myself.

Your best friend is you guessed it Google. I managed to download a PDF showing the actual board topology for a SAM unit and I realised one thing. The whole board is populated on its upper surface with Relays !

On further inspection something came under my eye.. highlighted above is a description of the N10/1149 relay that is responsible for SRS controls (Restraints control system)

I pulled out the front SAM unit and began inspection on the underside of the board for damage, there wasn't any (thankfully)

I retraced the N10 relay which is infact the gray box next to the two yellow ones

I pulled it out tested it using battery voltage and weirdly wasnt closing well... it took a second or so to close. something strange actually because relays are supposed to close instantly when powered

I tried my luck and bought a 12 USD dollar Relay from mercedes service centre (Iframac that time)

As soon as i replaced the relay everything was back to normal again all fully functional! That saved me well over 190dollars :)

Hope you enjoyed this post, keep on hacking :)

Arduino Controlled Fan

My very first arduino project was about 2 years ago, and it was (you guessed it) an arduino uno controlled 240V fan.. For reasons I don't know myself I never published it on my blog until today ;)

Concept

An arduino receives "data" from a RF receiver circuit and then controls a relay board which is in turn connected in a fancy way to a fan running on AC mains (more on this later). The arduino also controls a bunch of indicator LEDs and also a passive buzzer.

Parts List

1. The relay board in question (shipped from China - eBay reseller)

2. An ULN2003 darlington IC (for those who are unfamiliar with it.. Its basically made up of 7 npn transistors) 

3. This guy needs no introduction!

4. The target.. hmm

5. The Frankenstein Remote Controller (RF 49Mhz)

6. The RF receiver unit (holding it between my fingers)

7. Some funky LEDs... (who doesn't use LEDs these days :)

8. Opamp circuit I made which generates a 1Hz output.. toggles LEDS (red and blue) alternately added it too cause I liked it too much.. where's my handkerchief I'm getting emotional..

How does it work?

A fan which runs on mains usually has got one mains wire (coming from the power plug) connected to 

one tap of the AC motor of the fan... Therein 3 wires come out of the AC motor ( presumably from the 3 coils of the motor).. these 3 wires go to individual switches on a panel.. 

When you press on one switch .. this basically connects one coil to the other mains wire.. and the fan's RPM will be based on which coil was switched on.. does this make sense?

Hope the following diagram helps clear any confusion..

As you can see in the picture above, inside the motor we have 3 coils wound .. the resistance of the coils differ and that is why the fan spins at different RPMs.. 

What I did was I threw the switch panel away and rigged the relay board instead !

If by any chance the arduino would trigger 2 relays on at the same time it would surely cause the fan to release the "magic smoke" and maybe cause a fire...

So to avoid this I came up with a way to wire up it all as follows :

The "resistor" you see in the image represents the Coil impedance and not a resistor physically...

The topmost relay receives the mains power and when switched on .. feeds power to the 2nd relay...

The 2nd relay either powers up the primary coil or powers the third relay..

Third relay either turns on secondary or tertiary coil.. Nice story isn't it :)

This is a fail proof version that I came up with (atleast I think so).

Beware here is Frankenstein's remote controller !

If you take apart a cheap chinese toy you will find an RC receiver circuit which gives basically 4 outputs..

these outputs can be read by arduino and in turn arduino does stuff ..

What are those 4 outputs.. well one output makes the toy go forward.. one backward... one to the right .. finally one output makes it go to the left

You might be wondering there are 8 freaking pushbuttons on the remote controller above, what's this guy talking about?

One more diagram to help clear things out..

Yes effectively the extra row of buttons (5-8) short out buttons accordingly... this gives 8 functions out of 4

Some diodes had to be soldered to avoid "interference" in between button presses.. 

This LiPo above powers the transmitter.

Build Process (some snapshots)

Yes wires were soldered to the underside on the uno.. permanent installation plans..

I didn't want to have to poke around a barebones arduino with an FTDI chip in case I wanted to make a firmware upgrade .. so I used a cheap chinese uno from eBay..

Early "beta testing " of relay? :)

UNO having fun with the ULN2003.

Looks crazy as hell :P

Between notice 4 red wires on the right hand side of the picture.. these are wires from the AC motor.. one of them comes directly from the power plug and the other 3 are from the 3 coils of the AC motor..

The ugly thing in the middle is the power supply.. But it works! :)

Some info before you watch the video linked below:

NO two coils are on at once.

Button 1: Turns Fan ON - - Default speed is max

Button 2: Sets max RPM (again doesn't matter)

Button 3: Second Coil kicks in .. medium speed 

Button 4: Third Coil is on..  lowest speed

Button 5: Turn off the AC motor

Button 6: Turn on 1Hz opamp (the arduino could have toggled the LEDs itseld)

Button 7: Turn on timer mode... turns fan on at max rpm for 30sec.. then off for 5minutes .. cycle repeats (I love it )

Button 8: Disables the led toggling and timer mode disabled.

Video as promised (Please forgive the crappy camera .. I am sorry.. really..)

http://www.youtube.com/watch?v=QhCxQ6a-AZY

CONCLUSION

First, I would like to honestly thank YOU so much for going through this lengthy post.

This project was made using bare minimum parts as you have correctly understood, ofcourse to keep costs a minimum.. also that time I didn't have any coding skills I have today. :(

Well. Its been up and running for 2 years flawlessly so I never bothered improving the hardware yet but surely I would maybe in the future do any of the following:

1. Dump Frankenstein Remote and get an IR sensor with matching remote from eBay

2. Or maybe use a Bluetooth module like the HC-07 and thereby control the fan from my android phone

3. Maybe WiFi control? Is that too crazy? :)

That's it folks! I'm glad finally I did make a post about this project and I don't know what to type anymore so Cheers!!

A commonly used light source is the Fluorescent Tube.  Unlike other models.. old school Fluorescent tubes need a starter and a ballast to get going and you may end up waiting for a while till it finally gives you some light. And besides they get pretty noise and flickery which is a bad problem.

Above you can see the various components that sit inside the Fluorescent tube.

How about eliminating the delay in start-up completely? One solution is to shift to an electronic ballast!

So I decided to crack open a CFL (Compact Fluorescent Lamp) and take out the electronic ballast inside..

NOTE: If your bulb for example is 10W then look for a CFL with around 10W electronic ballast.

And this is what it looks like when you crack open a CFL.  You can see clearly an electronic ballast sitting inside.  Using a soldering iron , heat the metal on top of the CFL to get the two mains wires loose. 

DO NOT simply cut the electronic ballast wires close to the PCB board since there is a resistor / inductor (haven't figured out which one it is yet) soldered to one of the mains wire..

Once you pull the ballast out you will notice 4 pins on the front side of the pcb ... two pins on the left and two on the right

(I bent the pins a little for soldering later on)

Now time to crack open the Fluorescent tube.

You can see the old school ballast inside .. I removed the starter and discarded it already

You will notice a pair of wires coming out at each tube socket .. Cut them close to the ballast and starter if needed.. 

The pair of wires coming from one tube socket is to be screwed into a connector. Repeat for other tube socket So that in the end you land up with 2 connectors close by.

NOTE: The pair of wire coming from one socket is not to be connected to the wires coming from the other socket.. These pairs need to be separate..  and each pair has to have its own connector

Solder 4 wires to the electronic ballast pins... the two pins on the left side of the ballast connects to any one of the connectors... the two pins on the right side of the electronic ballast connect to the remaining connector

In this picture, you can see two pink wires coming from the left 2 pins of the ballast and going to one connector.  And 2 brown wires coming from the right 2 pins are going to the remaining connector

Here is a schematic in case what I typed above made no sense.. 

Make sure that no wires are shorting.

Testing the ballast on the tube reveals that it works exactly like a CFL as expected..

Finally use some duct tape to wrap the tape all around the electronic ballast and make sure again that there are no shorts .. You really don't want the metal casing to go live? Do you ? 

Well that's it fellow hackers! I hope you enjoyed reading this and thanks alot for your interest.

Have fun!