tda 7294 sub amp

[gcr]

hi all,
I purchased a sub woofer amp having two TDA7294. The problem is there is no paper attached with indication of inputs and outputs.

http://1drv.ms/1msQfSu
http://1drv.ms/1q2Kh0p
http://1drv.ms/1odF18E


I figured(???) input(Left ground right), and connected teflon wire(red,green,black), and output connected via red and black.
The problem is with power input. the seller told to power it using 27 0 27.
But i feed them with +18 0 -18(blue green blue) .( seeing +0- symbol on the board).But it didn't work.

Also no fumes came.
so, kindly help me to power this up.

regards
girish

 

[somakmaitra]

hi all,
I purchased a sub woofer amp having two TDA7294. The problem is there is no paper attached with indication of inputs and outputs.

http://1drv.ms/1msQfSu
http://1drv.ms/1q2Kh0p
http://1drv.ms/1odF18E


I figured(???) input(Left ground right), and connected teflon wire(red,green,black), and output connected via red and black.
The problem is with power input. the seller told to power it using 27 0 27.
But i feed them with +18 0 -18(blue green blue) .( seeing +0- symbol on the board).But it didn't work.

Also no fumes came.
so, kindly help me to power this up.

regards
girish

The output of htpreamp is not connected with the input of the power amp. Please have a capacitor bank PSU.
Regards
Somak

 

[gcr]

hello somak,
I'm using the following.

http://1drv.ms/1viVYQ3
http://1drv.ms/1qn6R5J

I used +18, GND, -18.

I thought when touching the input (hum) sound will come.
Also, i connected it to the preout.

regards
girish

 

[gcr]

hi all,
I will clarify my query.
1) How much volts it require?
2) I have a 27 0 27 transformer. Can i feed it directly without the (http://1drv.ms/1viVYQ3) psu?

regards
girish

 

[somakmaitra]

No connect with the psu, with 18-0-18 you will get 25 volts after filtering which is ok .Check the power amp by connecting an input from you mobile or mp3 player with a potentiometer .Connect the psu with a speaker and check if you get audio signal .
If it is working then you need to check the pre section .Also check the voltages of the PSU input and output .
Regards
Somak

 

[sarith]

Hello Girish,

Got your PM. Add a solid, large heatsink as TDA chip gets very hot. 8ohm speaker/woofer recommended. 25-0-25 trafo recommended. Unitek? power supply board shown in the pic can be used if it is not very old or too used.

If you are using a big woofer, better change the caps to a minimum of 6800mfd on power supply board (seems like 3300mfd? 50v keltron caps). You should not connect amp directly to transformer.

The 25-0-25 'AC' must be converted to 'DC' (35-0-35) using a power supply board and then that DC should be fed to your sub amp.

If you are a novice (seems like one) in diy, better get the help of a tech. There are stuff like dry soldering etc that should be considered while soldering. Soldering (wires) shown in the images of sub amp you posted is not good.

Rgrds
Sarith.

 

[gcr]

Hello Girish,

Got your PM. Add a solid, large heatsink as TDA chip gets very hot. 8ohm speaker/woofer recommended. 25-0-25 trafo recommended. Unitek? power supply board shown in the pic can be used if it is not very old or too used.

If you are using a big woofer, better change the caps to a minimum of 6800mfd on power supply board (seems like 3300mfd? 50v keltron caps). You should not connect amp directly to transformer.

The 25-0-25 'AC' must be converted to 'DC' (35-0-35) using a power supply board and then that DC should be fed to your sub amp.

If you are a novice (seems like one) in diy, better get the help of a tech. There are stuff like dry soldering etc that should be considered while soldering. Soldering (wires) shown in the images of sub amp you posted is not good.
Rgrds
Sarith.

thanks somak, sarith,
answers to sarith.
1) Its unitek power supply.Its having 2200mfd,50v.
2) I will be using 8 inch woofer. (old sub amp tda 2030 gone 3 months ago).
3) yup, you figured it right. heheheh. I'm soldering without flux. "dry soldering" I didn't heard about that. will search that.

My work will be a black mark for true DIY 'ers, right.
My curiosity keeps me trying these things.


regards
girish

 

[somakmaitra]

Hi
There is no black mark in diy .It is good to blow a few Power IC's to learn
But it can be addictive
Enjoy
Regards
Somak

 

[gcr]

Hi
There is no black mark in diy .It is good to blow a few Power IC's to learn
But it can be addictive
Enjoy
Regards
Somak

hi somak,
thanks.Its assuring.

Early i have tda 2030 amp with 8 inch sub . that i connected to my brothers mtx car subwoofer(big one) that was lying idle. Fumes came from both IC's .(it was 2/3 months ago) heheh.
thank god.nothing happened to subwoofer:yahoo:.

yesterday, i gone to electronics shop for Led, i saw the sub board and purchased.
they had 3 types of boards.
1) one ic with vol control (27 0 27 ). feels like fastfood. so rejected it.
2) two IC, markings there.(that i purchased)
3) four IC, seems complicated (http://1drv.ms/1maTTGk) took photo.

regards
girish

 

[gcr]

me back after the dramatic match.
At half time, when i watched the amp board closely, i saw SPKR b/w IC and heat sink. Also, from net i collected the following information.
http://www.wvshare.com/img/pinout/TDA7294_l.jpg
TDA7294 Mini PCB 200W Elektronik Sitesi

http://320volt.com/wp-content/uploads/2012/07/tda7294-mono-baglanti-semasi.png
http://320volt.com/wp-content/uploads/2012/07/tda7294-pcb-olculeri.png

then i realized, i had connected wrongly.now, i'm going to connect properly and power it up.

thanks
girish

 

[sarith]

I forgot that unitek board used to put 2200mfd caps a decade ago. I have made them put 3300mfd instead for my use those days. For 8" woofer that worked with 2030, 2200mfd x 4 caps are enough.

When soldering, follow proper method. You are dealing with power here.
How To Solder - YouTube. Using flux is good. (precaution is better than cure)

You could have bought a Transistor based mono amp board instead of bridged 7294. 5200/1493 Toshiba, IR Mosfet, TIP etc would work well with 27-0-27. A single chip 7294 would have been enough too. All you have to do is add a sub filter to any of the mentioned amps. Anyway, carry on with this one.

Nothing like black or white mark. Diy is more like a passion. My early works, though not that bad, might make me or others laugh today..but that's the initial experience/stage for most diyers I guess.

Curiosity killed the cat ..It's good to be curious. I was too. I have experienced more than a dozen of serious shock hazards and it's not cool. Be safe. Have fun

The pic shows different type of soldering iron and tip, flux etc. I haven't put the pic of my liquid flux as I felt it is irrelevant at this point. Some basic stuff you need - a good soldering Iron (soldron, goot, weller etc), Flux (goot, amtech etc ), soldering lead, de-soldering pump and wick, iron tip cleaner, iron stand, magnifying glass, cutting/snipping tools etc..There are some other stuff for convenient/pro soldering.

Just saw your transistor amp pics. A single channel of that Mosfet (IR) amp is good enough for your 8" woofer. They seem to use rectangular aluminium tube instead of proper heatsink (for demo purpose I think). Use proper heatsink, thermal compound (paste) and if necessary, new insulators (mica or other)

thanks somak, sarith,
answers to sarith.
1) Its unitek power supply.Its having 2200mfd,50v.
2) I will be using 8 inch woofer. (old sub amp tda 2030 gone 3 months ago).
3) yup, you figured it right. heheheh. I'm soldering without flux. "dry soldering" I didn't heard about that. will search that.

My work will be a black mark for true DIY 'ers, right.
My curiosity keeps me trying these things.


regards
girish

 

[saheb11123]

hi somak,
thanks.Its assuring.

Early i have tda 2030 amp with 8 inch sub . that i connected to my brothers mtx car subwoofer(big one) that was lying idle. Fumes came from both IC's .(it was 2/3 months ago) heheh.
thank god.nothing happened to subwoofer:yahoo:.

yesterday, i gone to electronics shop for Led, i saw the sub board and purchased.
they had 3 types of boards.
1) one ic with vol control (27 0 27 ). feels like fastfood. so rejected it.
2) two IC, markings there.(that i purchased)
3) four IC, seems complicated (http://1drv.ms/1maTTGk) took photo.

regards
girish

If you don't mind me asking , what was the price of the "four ic" amp?
They are mosfet based amp, would have been better though...

 

[gcr]

I forgot that unitek board used to put 2200mfd caps a decade ago. I have made them put 3300mfd instead for my use those days. For 8" woofer that worked with 2030, 2200mfd x 4 caps are enough.

When soldering, follow proper method. You are dealing with power here.
How To Solder - YouTube. Using flux is good. (precaution is better than cure)

You could have bought a Transistor based mono amp board instead of bridged 7294. 5200/1493 Toshiba, IR Mosfet, TIP etc would work well with 27-0-27. A single chip 7294 would have been enough too. All you have to do is add a sub filter to any of the mentioned amps. Anyway, carry on with this one.

Nothing like black or white mark. Diy is more like a passion. My early works, though not that bad, might make me or others laugh today..but that's the initial experience/stage for most diyers I guess.

Curiosity killed the cat ..It's good to be curious. I was too. I have experienced more than a dozen of serious shock hazards and it's not cool. Be safe. Have fun

The pic shows different type of soldering iron and tip, flux etc. I haven't put the pic of my liquid flux as I felt it is irrelevant at this point. Some basic stuff you need - a good soldering Iron (soldron, goot, weller etc), Flux (goot, amtech etc ), soldering lead, de-soldering pump and wick, iron tip cleaner, iron stand, magnifying glass, cutting/snipping tools etc..There are some other stuff for convenient/pro soldering.

Just saw your transistor amp pics. A single channel of that Mosfet (IR) amp is good enough for your 8" woofer. They seem to use rectangular aluminium tube instead of proper heatsink (for demo purpose I think). Use proper heatsink, thermal compound (paste) and if necessary, new insulators (mica or other)

Thanks sarith for your detailed description.
So, i will change 2200mfd to 6800mfd as per your first post.

I felt it will be complicated. i.e why i opted the single board (filter +board)
I have the soldron 25w iron.

As i mentioned, there were no proper markings on the board nor instructions. so i skipped that.
It was a proper heatsink.

update: sub worked after changing the connections.
speaker connection was wrong.

(spkr was written on board, but it was not visible)

SPKR and filter I/P was not connected before, it was left blank.
now its working.

regards
girish

 

[gcr]

If you don't mind me asking , what was the price of the "four ic" amp?
They are mosfet based amp, would have been better though...

Thanks saheb for pointing it out. heheheh.
I didn't checked/ unaware of that. just took photo thinking help from you guys made me to finish that.may be next time.
I was on the verge to purchase that, but didn't bought.
please check your pm.

regards
girish

 

[saheb11123]

Thanks Pm replied..

 

[gcr]

update:
Its working... significant change from TDA2030. But heat sink gets hotter after half an hour itself. So i placed 12v dc fan to cool it. No much heat after two hours then. Happy with the outcome.

A BIG thanks to saheb11123, sarith, somakmaitra, bibin, bijin for helping me in completing this.

regards
girish

 

[sarith]

Well done..and you are welcome Girish.

update:
Its working... significant change from TDA2030. But heat sink gets hotter after half an hour itself. So i placed 12v dc fan to cool it. No much heat after two hours then. Happy with the outcome.

A BIG thanks to saheb11123, sarith, somakmaitra, bibin, bijin for helping me in completing this.

regards
girish