How i fixed blue tooth to Audio mixer and worked perfectly

Hi Dear friends,

Welcome back again to Electronic Repair Article. In the modern audio system Blue tooth is playing very important role. This is because it’s very flexible to the User which eliminates completely plug and play audio jack system from your android smart phone to relevant audio player.

This blue tooth system is now very popular in all most all the modern audio systems from cheaper end to higher end audio player devices,

In those days our generation people had the  life  like one Tape cassettes memory only 10 audio songs followed by CD'S,DVD'S, blue ray disks and USB by gradually increased their respective memory space size depending one's their choice.

Now blue tooth Audio players occupied their places. With the introduction of the Internet, smart phones and android apps peoples are attracted much more on blue tooth devices because this is also eliminating storage and maintains. Peoples directly extract the data or audio files from the web.

Some of the peoples throwing their old professional audio equipment's to dustbin and busy in purchasing Modern blue tooth audio devises.

As we know PA audio systems are very high cost and we don't have a mind to throw dustbin because of blue tooth non availability.

Below my story is the solution for the above problem let me begin my story,

One of my costumers brought a PA audio mixer for repair which is completely dead. He said if repair cost more not to repair and he is in the mood of purchasing new mixer with blue tooth technology.

As per his instruction started to debug and there was a problem in the input power section resulted step down transformer primary open replaced the same and made it up and re-gained life.

Even though the costumer was not happy because he was completely attracted to modern blue tooth based mixer. He was in the mood of throwing to dustbin. When i played this repaired mixer with audio jack played excellent very high quality sound questioning myself such beautiful equipment and higher end audio mixer why he is throwing dustbin? Is there any solution to convert this into blue tooth? The answer is yes.

Here is the chip. Hats off to the inventor. Using this below chip one can convert any audio system into blue tooth starting from lower end to heigher end audio system.

Below is the list you can convert to blue tooth with similar steps

1) Old home theatre audio systems

2) Proffecionsl audio mixer

3) Any audio amplifiers

4) Very old cassette /CD/DVD Audio players

5) Public address audio systems

6) Power amplifiers

7) CRT/LED/LCD tvs etc

8) Automobile audio systems and  sub amp systems

.

As continue repair story after replacing defective step down main transformer and tested the audio output with aux input jack connection via my smart phone resulted excellent sound output when i hooked to my power amplifier .My next task is conversion it in to wireless blue tooth technology.

Blue tooth module :-



BLUE TOOTH CHIP

 Below is the steps i have taken for the conversion and resulted success.

1) Finding the controlled audio input path for both left and right channel

  

Below is the points in finding controlled audio input path in any amplifier and is very easy as a clue

a) middle pin of the volume controller( Old classical method)

b) Audio amplifier ic data sheet in an internet or data sheet book

c) Aux input paths (Usually almost all the amplifier will have aux input/output points)

How i have done:-

Hear for the conversion what i have selected  is audio mixer which is messed with number of volume controllers leads to confusion .

A professional audio service engineer will easily finds the connection points but for the new comers its quite confusion. We need to go in a systematic way.

Please note the below point what i have done to find the audio input points. Just i played the audio track with the usb and tracked the AUDIO signal flow using my oscilloscope probe.





Audio signal flow tracking using Oscilla scope

Now, raised and lowered input level using mixer channel volume control to check the out put level. Audio amplitude waves varied in my oscilloscope accordingly; ultimately i got the Controlled audio input point as shown below.



Audio input points both left and right channel

Above points are identified and found controlled audio input points RIGHT, Gnd and LEFT Channel

Which is wired via core cable?

2) Finding the ripple free pure 5volt/500ma  and chassis  ground path.

For the blue tooth chip operation fine ripple free 5v/500ma Regulated power supply is required.

Generally we know professional audio equipment will operate more than 12volts depending upon their wattage. Here in my case (Audio mixer) it is operating 12 volts DC .We can use this voltage to convert 5volts using 7805 Regulator.

Identified 5Volts DC in the mixer

Since this mixer is hooked with module USB Audio and FM Radio player which is operating on 5volts already present. Identified the 5volts point and soldered as shown.



Bluetooth chip installed

All the points are soldered and now the time is ready for the testing, I have taken my Samsung smart phone and turned on the blue tooth in Mixer ON condition. Got th BT3.0 Symbol and paired.

Played my mp3/mp4 files excellent output. Checked the distance wireless about 15 meters got the power output without any disturbance. Happy to see this and share my success story in this blog.

Audio 6 channel mixer undergone for Bluetooth conversion

Dear repair friends please don't allow your customers to throw their old audio equipment's to dust bin. Convert them into latest blue tooth audio player as i did to above audio mixer. You can convert any audio equipment into blue tooth as stated in the list above. Hope you enjoyed my blue tooth conversion story meet you in the

Next session take care.

Best regards

Basavaraj BM

The story How i converted hot blower into bench power supply 35 volts/15 amps

Dear friends Based on the demand i am writing this article on bench power supply which delivers up to 35 volts/15 amps.
We came across many articles on bench power supply in internet by simply  using computer SMPS and ordinary step down transformer etc. They are  useful only for beginners and hobbyist not for professionals. This present story is very useful for professionals.
High voltage and currents power supply are very expense starting  from 5k to more then lakh rupees  depending up on the brands, model, voltage and current ratings. Manufacturers will fix price very expensive depending up on their Models.
Bench power supply play very important role in powering AVR  based inverters/voltage stabilizers/ups repairs  and variable  AC  and DC voltage /Current controlled power supply.
Below is the story how I made it and even today working fine in  my repair activity.

In my Junk i found an Un-repairable Hot air blower. Made my mind to make use of that for variable power supply.

Started to fix the components inside the chassis by making satiable cuttings for digital ammeter/ volt meter as shown below, pls go through the photo below for your understanding.

Hot air blower chassis made empty 

Chassie is been cut and fixed volt meter and ammeter as in the photo below.Now coming to the working principle and electronic theory of an instruments is a  very simple rectifier circuit which converts AC to DC.

Volt meter size cutting done

Now question in mind is how to vairy input to step down transformer  and again to get veriable  35 volts AC to rectifier circuit  because hear instrument what we are making is a veritable DC power supply.

Yes, the Technic hear is very simple varing 230 volt ac to step down transformer  35-0-35/15 Amps  between 0 to 260 volts ac up to desired level.

Step down transformer fixed with bridge rectifer

Below are the components selected to design the circuit 

1) 35-0-35 / 15 amps step down transformer 1#

2) 500 watts  ac bulb Dimmer 1#

3) 6800mfd 35volts  electrolytic capacitor 1#

4) High current rectifer doides 4#

5) 10k 10 watts fixed resistance as a load resister

Please go through the circuit diagram presented below for your understanding 

CIRCUIT DIAGRAM

Bulb dimmer:-

Below is the typical variac type dimmer  which is used to control the ac loads and is very cheap when compared to Costly  lab variac.

In my project  as per  above circuit diagram you can use to vary 230 volt ac starting from 0 to 260 volts and control the step down transformer output accordingly and set the final output ripple free DC output and same can be monitored in the respective volts/current panel meter.

Important to be noted this project will work on only by using variac type dimmer because in market will be available triac based dimmers still cheap but won't work on transformer loads and ultimately miss lead you resulting failure.

Typical bulb dimmer

Every one knows working principle of rectifier .Hear logic what i made is just varing the input voltage level  using ac bulb dimmer it just acts as Variac and controls the input ac voltage to the rectifier circuit and produces the ripple free DC and can be used to run various dc loads for repair working and parallely we can monitor the out put voltage and current status  in the panel after powering the bench test equipment's.

Volt meter and ammeter fixed front view

Appearance an power on condition

One more thing here short circuit or over load protection circuit is not included. If you are export in electronic circuit designing one can create their own design for the safety propose.

To the best of my knowledge what i presented here is more enough and act as a good bench test instruments.

Hope this article may be useful to you in constructing the  needy test equipment instead of purchasing costly DC source. And i again  hope you enjoyed this i will be back with one more interesting topic in the next episode. 

With best Regards

Basavaraj BM