TDA2050 not working

[chingyg]

I've decided to build some amplifiers out of TDA2050. first I used the bridged schematics from the TDA2030 datasheet, upon powering (computer SMPS, modified, +14V and -24V) one of the chip exploded. wiring is checked and check then a single chip split supply circuit is built (from the TDA2050 datasheet) upon powering only DC comes out from pin4 of the chip. I tried single supply circuit, but nothing comes out from the output. I changed the power supply to an unmodified computer SMPS +-12V, same thing happens no output.

What could be wrong with the circuit, by the way it was constructed on breadboard for prototyping.

thanks in advance

[Iain McNeill]

When chips explode it's usually due to being wired backwards or due to shorts. It's easy to get a whisker of solder between two adjacent pins.

When it exploded, it probably took out some other components as well and this may be why it still doesn't work even with new IC's.

Do a GOOD visual inspection and check every wire & connection against the schematic. If that doesn't show a fault then you may need to check each component with a meter.

[wahab]

with a single rail power supply, and thus an output capacitor,
these circuits needs two diode connected in reverse from the
output of the IC (before the capacitance) to positive supply and ground...
it s noticed on ST micro application notes...

[chingyg]

I've found the error, there was huge voltage spikes on the -12V line, the peak is about 32V, it destroyed 3 of my TDA2050s, now i have to replace them, shame.

[Iain McNeill]

That would do it. Good detective work

I always test the PSU separately before adding on the amps for exactly these kind of reasons.

[chingyg]

It was hard to detect though, the multimeter reads only -14V, but there were -28V spikes in the line, I only found out when I connected a capacitor across the supplies.

[psychosteve72]

first, you say "(computer SMPS, modified, +14V and -24V)" if your design is dual supply you will need equal +ve and -ve voltage, other wise you will shift the mid voltage point and get dc at output, more than that computer power supply's are not designed to give the output current on the -ve line, they can be modded but never satisfactory in my experience.
second as has been said, get one thing working at a time, i usually start with a simple transformer power supply any lowish voltage dual output will get you working, some old pc speakers with direct mains (not plug adapter) had a small dual output transformer with rectifier and caps. failing that an old hifi. you would be down on power output but should get you going. be safe with mains voltage!

hope this helps, steve.

[chingyg]

thanks for the advice, I am putting everything together in a box next week. its going to be called the boomitron, I'll upload some photos if I see fit.