Powered on, with BD modulation, each of the +, - speaker outputs sits at 1/2 Vcc. I was using 24V and observed 12V, referenced to Vcc ground at the speaker outputs.
With the amplifier on, I connected the outputs across two, 220 Ohm resistors to ground, each having ~50 mA going through them, with a ~10,5V voltage drop across each. The voltage drop then simply shifted up to 12V...the output Z of the amp being much, much lower than 220 Ohms. Amplifier functioned driving into this situation without issue.
Then I got the bright idea to turn off the TPA3116 amp via its power switch, figuring the outputs would simply go "tri-state", or non-conducting. Voltage drop across the two, 220 Ohm resistors resumed back to the ~10V value. Looks like tri-state to me.
Turning the amp back on I expected it to go back to 12V, but - nothing. No output, audio or DC. Nothing after power cycle, connected to ordinary speakers the ordinary way - something killed it dead.
I was powering it using a battery, so it was truly floating relative to the other circuit. Battery Vcc (-) was the only connection to the same ground as the two 220 Ohms resistors were connected to, each with, again, ~10.5V across it.
TLDR; I backfed 10.5 V into the speaker outputs of my TPA3116, relative to its ground, with a whole 50 mA of umph behind it - and it killed something inside the chip. How could that be? No magic smoke, noises - just no functioning output anymore.
Any ideas what happened to the chip in that amplifier? One could go 'round killing them all with a 9V battery and some clip leads - apparently!
With the amplifier on, I connected the outputs across two, 220 Ohm resistors to ground, each having ~50 mA going through them, with a ~10,5V voltage drop across each. The voltage drop then simply shifted up to 12V...the output Z of the amp being much, much lower than 220 Ohms. Amplifier functioned driving into this situation without issue.
Then I got the bright idea to turn off the TPA3116 amp via its power switch, figuring the outputs would simply go "tri-state", or non-conducting. Voltage drop across the two, 220 Ohm resistors resumed back to the ~10V value. Looks like tri-state to me.
Turning the amp back on I expected it to go back to 12V, but - nothing. No output, audio or DC. Nothing after power cycle, connected to ordinary speakers the ordinary way - something killed it dead.
I was powering it using a battery, so it was truly floating relative to the other circuit. Battery Vcc (-) was the only connection to the same ground as the two 220 Ohms resistors were connected to, each with, again, ~10.5V across it.
TLDR; I backfed 10.5 V into the speaker outputs of my TPA3116, relative to its ground, with a whole 50 mA of umph behind it - and it killed something inside the chip. How could that be? No magic smoke, noises - just no functioning output anymore.
Any ideas what happened to the chip in that amplifier? One could go 'round killing them all with a 9V battery and some clip leads - apparently!
Hello,
did you consider that TPA3116 have half bridge transistors on the one polarity and on the other polarity it also have second half bridge.
Everything is ok when each speaker polarity have same DC voltage.
You should not connect any load to power supply GND (this is what you do with 220 ohm resistor).
If amp sounds OK, I wouldn't worry.
did you consider that TPA3116 have half bridge transistors on the one polarity and on the other polarity it also have second half bridge.
Everything is ok when each speaker polarity have same DC voltage.
You should not connect any load to power supply GND (this is what you do with 220 ohm resistor).
If amp sounds OK, I wouldn't worry.
Amp is dead. The 220s to ground didnt seem to hurt it, when operating. They had 12V across them and the output was only supplying 1.2W of DC power - from essentially a half-bridge switching regulator output. Chip itself supposedly does 50W.
There's internal circuitry connected to the amp output terminals, besides the half bridge transistors. Probably killed that...
There's internal circuitry connected to the amp output terminals, besides the half bridge transistors. Probably killed that...
Tri-state is a Digital thingie and even so, only on specially designed chips.
Power transistors are robust only if forward biased and "they" can control amount of current passing.
Unpowered they become a bunch of diodes, best case, and if not, fragile semiconductor crystals with weak junctions .
I am sick of the following situation:
"what happened here?"
" oh, I was testing a new Guitar amp head so I connected it to the speakers in my combo amp .... but don´t worry, I did not turn it ON"
Same thing, same results: very dead power transistors.
Power transistors are robust only if forward biased and "they" can control amount of current passing.
Unpowered they become a bunch of diodes, best case, and if not, fragile semiconductor crystals with weak junctions .
I am sick of the following situation:
"what happened here?"
" oh, I was testing a new Guitar amp head so I connected it to the speakers in my combo amp .... but don´t worry, I did not turn it ON"
Same thing, same results: very dead power transistors.
The 9v/clip leads hypothesis seems interesting but unconfirmed. Are you going to test it? Perhaps a weak 10.5v is the sweet spot in the killing field.