Velleman K4040 (TDA 1514) amp problems

[MrSensitive]

Hi all,

I built a power amp using 4 K4040 kits resulting in 8 50W channels.

I have two transformers and 2 power supply modules each providing power to two modules.

the problem is that the modules connected to one of thepowersupply's keeps destroying the TDA chips (not always, but somethimes when turing the amp on, one of the chips just starts smoking..)

would a soft start circuit be the solution here?
i did some calulations, and the rail voltage is really at the max limit.

the other two amps work perfectly.. (maybe the rail voltage is a bit lower here?)

thanks

 

[Pavka]

In my oppinion the smoke is from switch-on peaks, only solution is (not very practical) some overvoltage protection (zener diode or so). But I left this IC after having smoked a few of them.

Happy amplifiing

 

[dhaen]

This IC is very reliable at lower power / voltages, but I wouldn't use it anywhere close to max ratings. It has none of the built-in protection that some of the current National Semiconductor chips employ.
I think it's officially obsolete now. It certainly does need a lot of external components compared with current chips.

 

[MrSensitive]

It is running pretty close to the limits.

and yes , it seems to be hard to find replacement chips.
damn, I have 4 boards each using 2 chips, 2 of them died.

why did Velleman include transformers that push the chip to (or across) it's limits...

 

[dhaen]

If the transformers are toroids, you can add some extra turns and connect these to subtract from the secondary voltage. A 5v drop will be quite practical.