Hi! I need your help, one more. I set up this sound amplifier I bought from ebay:

http://www.ebay.co.uk/itm/TPA3116D2...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

and it's powered with a 18 Volt laptop charger. The problem I have is when turning it on and off, it does a huge noise. Is it some sort of voltage peak or something like that? It may need a capacitor, but I'm not sure where and which capacitor should I use. I don't want to mess with my amplifier board before I heard from someone who knows more than I.

I made a video with the issue, it may not seem very loud, but it is a little bit.

P.S. The magnificent cardboard box is only temporary, I'm designing a new one

Best regards,
João Dias

 

Your video is set to "private" and cannot be viewed.

 

Your video is set to "private" and cannot be viewed.

Thank you! I'll set it public.

 

Just a thought: Do you still get the thump if you turn it on by plugging the laptop charger into an outlet and off by unplugging the charger?

 

0Just a thought: Do you still get the thump if you turn it on by plugging the laptop charger into an outlet and off by unplugging the charger?

At first I didn't have the switch to turn it on and off, I just plugged and unplugged the transformer from the AC whenever I wanted to turn it off and on, and the thump still happened. I thought putting a switch would solve the problem because after I unplugged the transformer the circuit still receives some voltage from the transformer. And yes, the thump still happens if I don't use the switch, and it's a little bit louder.

 

What is connected to the inputs, and what is the source of the input signal doing when you switch the power on and off?

What are the SDZ (pin 2) and Mute (pin 12) pins doing during power-up and power-down?

From the datasheet:
7.3.3 Startup and Shutdown Operation
The TPA31xxD2 family employs a shutdown mode of operation designed to reduce supply current (Icc) to the absolute minimum level during periods of nonuse for power conservation. The SDZ input terminal should be held high (see specification table for trip point) during normal operation when the amplifier is in use. Pulling SDZ low will put the outputs to mute and the amplifier to enter a low-current state. It is not recommended to leave SDZ unconnected, because amplifier operation would be unpredictable. For the best power-off pop performance, place the amplifier in the shutdown mode prior to removing the power supply. The gain setting is selected at the end of the start-up cycle. At the end of the start-up cycle, the gain is selected and cannot be changed until the next power-up.

 

I didn't remember I could see the datasheet! Thanks for that. I'll have to remove the heatsink and will try do see the voltage values of those pins, thanks for noticing it. About your answer, the input is from my computer. But I've found one video on youtube which has the same problem (I guess, and he points to the PIN you specified) the SDZ and the MUTE.

But the video isn't in English, I will have a bad time trying to understand. But I'll try to investigate more this problem.

"The SDZ input terminal should be held high (see specification table for trip point) during normal operation when the amplifier is in use. Pulling SDZ low will put the outputs to mute and the amplifier to enter a low-current state." I can make sure this happens, although I'm not seeing how I could guarantee this: " For the best power-off pop performance, place the amplifier in the shutdown mode prior to removing the power supply.".