I have bulid BTL tda7294, with 350W Ei transformer, +-40vdc. If u use to many robus capatitors u have to use some "soft start" for power suplly. I think the speaker can't blow when amplifier is powered on, because tne IC have protection for speaker, so the speaker is "on" after 1-2 second after turning on switch on power suply. Maybe u have chek qualiti of desing, shor circuit maded during soldering, or some errors in desing. My amlifier worket in firs time, i have used 4x4700uF 150W speaker....
It still amazes me why people use these vastly over-dimensioned transformers, couple them to huge reservoir caps, and then wonder why it blows fuses. At startup this transformer and rectifier is pretty much a near-short on the AC power line. You need a soft start circuit, a NTC resistor at the very least. It can be as simple as a 48V relay and a big power resistor.
Secondly, there are a number of speaker protection circuits available in kit form. Look up Velleman kits.
Your schematic is Ok and and should work provided it has been laid out correctly and the chips are not fakes. Sometimes sellers will re-label lower voltage parts from the same series that don't sell, and these will fail at higher voltages.
Also READ THE DATASHEET. It clearly states that the chip itself cannot handle the full heat dissipation at +-40V power supply, and gives a special class G application schematic, which everyone seems to bluntly ignore.
The chips do not have a tendency to explode on their own, unless you have not connected them properly. In particular, if either of the -V power pins is not connected to the supply line, the chip will go into latch-up and destroy itself instantly.
Secondly, there are a number of speaker protection circuits available in kit form. Look up Velleman kits.
Your schematic is Ok and and should work provided it has been laid out correctly and the chips are not fakes. Sometimes sellers will re-label lower voltage parts from the same series that don't sell, and these will fail at higher voltages.
Also READ THE DATASHEET. It clearly states that the chip itself cannot handle the full heat dissipation at +-40V power supply, and gives a special class G application schematic, which everyone seems to bluntly ignore.
The chips do not have a tendency to explode on their own, unless you have not connected them properly. In particular, if either of the -V power pins is not connected to the supply line, the chip will go into latch-up and destroy itself instantly.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.