Help find replacement board with Tda7294 chip

[Urielp]

Hi all,

I am currently trying to fix a sub that i got and i think that i ruined the amplifier board.
I tried to look for replacment and i did not find any.
Tried to contact the manufacturer but he refuse to provide one.
The board is based on Tda7294 chip,
The attached image is the board that i want to replace.

Can anyone please advise?

Thanks in advance

 

[Fast Eddie D]

Hi all,

I am currently trying to fix a sub that i got and i think that i ruined the amplifier board.
I tried to look for replacment and i did not find any.
Tried to contact the manufacturer but he refuse to provide one.
The board is based on Tda7294 chip,
The attached image is the board that i want to replace.

Can anyone please advise?

Thanks in advance

There's millions of pre-assembled chip amps on Flea Bay.

What's the power supply voltage? Is it a split supply?

If you can't answer these simple questions, then step away from the soldering iron.

 

[Urielp]

sorry,you are right,
i forgot to attched some pics witht the info,
and i must say that i like the soldering iron 🙂

this is the specification from the manufactor site :

Driver 8” WOOFER
4 Ohm RMS Power 100W
Total Efficiency >80%
Frequency Response 45Hz-150Hz
Crossover Variable 50Hz to 150Hz
Distortion <1%
Signal to Noise Ratio ≥90dB
Bass Boost (35Hz) +6dB
Input Sensitivity 5mV
Auto Power on Sensitivity 115mV
Temperature 65c
Hi Level Input Sensitivity 1.2V
Hi Level Output Sensitivity 1.2V
Input Power AC115V & 230V

i think i found the facotry that manufactor this sub ,but they refuse to sell any replacment part.
Hi FI active subwoofer SUB 8 creative subwoofer, View active subwoofer china, audio live Product Details from Vistron (Dongguan) Audio Equipment Co., Ltd. on Alibaba.com

i also thinking of using diffrent parts but this is connected to control panel that in charge of stand by/phase/volume etc so need somthing that can connect to that.

 

[Fast Eddie D]

Total Efficiency >80%

Impossible.

No loudspeaker is even close to 80% efficient. Anything over 1% is remarkable.

No class AB amp is close to 80% efficient.

You "manufacturer" is peddling snake oil. It's no different than an auto mechanic that sells you blinker fluid. I've reverse engineered dozens of consumer audio products and most "manufacturers" just mix up a bunch of cheap junk that someone else built. This even goes for "high end" consumer stuff like Onkyo, who to their credit build their own amplifiers but all the DACs, control boards, DSPs, etc are "embedded solutions" that they just splice in there. This is the exact same junk you buy on Flea Bay. It makes me wonder if some of these "manufacturers" have an actual engineer on their staff, because anyone with a little knowledge of electronics could do what they do, and do it better.

I pulled a JVC subwoofer out of the dumpster. The power amplifier was incinerated. I put a cheap TDA something board in there that I bought for $10. Fixed. It's a piece of crap, but it was a piece of crap when it was brand new.

 

[DUG]

How about this?:

Dayton Audio SA100 100W Subwoofer Plate Amplifier

 

[Fast Eddie D]

How about this?:

Dayton Audio SA100 100W Subwoofer Plate Amplifier

That's probably nicer than what they put in most subwoofers from the big box store.

I don't think you can beat that for the money unless you want to go real cheap and wire a bunch of Flea Bay junk together.

I have some Dayton Audio stuff. It's top notch for the money.

 

[Urielp]

funny that you mention the JVC story, @Fast Eddie D,
i also found this sub in dumpster ,it did not worked due to bad chip and blown capacitor,
and this manufactor is supposed to be one of the top speaker manufacto here.
and this sub model should be nice to small system.i just really wanted the challenge.

@DUG,it could be good solution if i wont be able to find a replacment for that board,

 

[sgrossklass]

That amplifier board doesn't look too "ruined" to me (no holes burned into it or anything), what's wrong with it apart from possibly a bad TDA? I only spot some suspicious black mounting glue, that stuff will have to go ASAP and parts covered by it inspected for corrosion / replaced if necessary.

 

[Urielp]

The issue is in the other side,
The connections of the tda gone bad, some of them lost the connection and only plastic was left, i manage to do sove override , but still not working, it is no more blowing fuses but it is just stuck in stand-by mode

 

[Fast Eddie D]

The issue is in the other side,
The connections of the tda gone bad, some of them lost the connection and only plastic was left, i manage to do sove override , but still not working, it is no more blowing fuses but it is just stuck in stand-by mode

The board was poorly assembled, and it overheated. It was probably not adequately designed in the first place.

 

[Fast Eddie D]

The issue is in the other side,
The connections of the tda gone bad, some of them lost the connection and only plastic was left, i manage to do sove override , but still not working, it is no more blowing fuses but it is just stuck in stand-by mode

Also, unlike other popular chips, some of the TDA chips will burn up when the leads start separating from the circuit board. It depends on which leads come up first. That's because some TDA chips have separate leads for the power supply to the output stage. If you power up the driver stages first, it will smoke one of the output devices. The purpose is so you can apply s higher supply voltage to the driver stages, allowing the MOSFETS to be driven closer to saturation.

And TDA chips aren't that good for hi-fi anyway, because they have rising distortion with frequency. They're a logical choice for a cheap subwoofer though. They can be easily paralleled without a problem, unlike popular BJT chips. Some of them are designed to be paralleled. So with a bridge/parallel circuit, you could get a lot of power for real cheap.

 

[nigelwright7557]

Its probably the TDA as not much else to go wrong.
Unless power supply died ?
Cut off TDA pins as high up as possible then heat the pins up and grab quick with long nose pliers and pull them out. Not the easiest of jobs but I have done them without too much grief.

 

[Urielp]

Hi,
Thanks
The power supply is working fine, and i did manage to replace the chip again, now, for som reason it is always on standby mode, and wont turn on &#55358;&#56596;