I've got a tpa3118 pbtl board that I want to use with MH-M18 Bluetooth module (picture in the last) and 3.5mm audio jack input both in mono mode. So I came up with this circuit.
I mixed L/R from both bluetooth and audio jack through 330E resistors and gave them to IN+ of amp selectable through a DPDT switch. (ignore the volume pot RP1 and resistor R5 since I did not connect them).
I planned on using the second pole of dpdt switch to connect audio grounds of bluetooth and audio jack separately to IN- of amp but since my bluetooth module has common ground for audio and power, and my buck convertor (for powering bluetooth) also has common ground for i/p and o/p, so I connected all grounds together and used that second pole of dpdt switch to turn the bluetooth on and off. I suspected that it connecting all grounds can cause come issue but I went on. On the output there is a woofer 4ohm/15W for testing and main power supply is 24v 2A dc smps.
On firing everything up, things went normal, music played in both BT and aux mode for sometime. After about a minute or so, music playback stopped and I got constant rhythmic ticks from speaker 1seconds apart.
Disconnected everything and just connected power and speaker to the amp (nothing on input) and got the same ticking sound.
Going through various forums, I suspect that the 3118 is going in some protection mode for some reason. Also, the board seems to follow the layout mentioned in the datasheet of tpa3118 shown below.
On checking this board with a continuity tester after this accident, I found that IN-, OUT- and PWR- are all shorted which shouldn't be as per the layout above. Maybe that is why the amp is going in protection mode.
I am hoping that since it is going in protection mode, there should be a way of fixing this issue. Need help on that.
Also need a guidance on how should I connect Bluetooth having common gnd to amp and power supply keeping gnds separate.
I mixed L/R from both bluetooth and audio jack through 330E resistors and gave them to IN+ of amp selectable through a DPDT switch. (ignore the volume pot RP1 and resistor R5 since I did not connect them).
I planned on using the second pole of dpdt switch to connect audio grounds of bluetooth and audio jack separately to IN- of amp but since my bluetooth module has common ground for audio and power, and my buck convertor (for powering bluetooth) also has common ground for i/p and o/p, so I connected all grounds together and used that second pole of dpdt switch to turn the bluetooth on and off. I suspected that it connecting all grounds can cause come issue but I went on. On the output there is a woofer 4ohm/15W for testing and main power supply is 24v 2A dc smps.
On firing everything up, things went normal, music played in both BT and aux mode for sometime. After about a minute or so, music playback stopped and I got constant rhythmic ticks from speaker 1seconds apart.
Disconnected everything and just connected power and speaker to the amp (nothing on input) and got the same ticking sound.
Going through various forums, I suspect that the 3118 is going in some protection mode for some reason. Also, the board seems to follow the layout mentioned in the datasheet of tpa3118 shown below.
On checking this board with a continuity tester after this accident, I found that IN-, OUT- and PWR- are all shorted which shouldn't be as per the layout above. Maybe that is why the amp is going in protection mode.
I am hoping that since it is going in protection mode, there should be a way of fixing this issue. Need help on that.
Also need a guidance on how should I connect Bluetooth having common gnd to amp and power supply keeping gnds separate.
System constantly in protection means something is shorting in the chip. Or the protection should be reset. I think your ic is done . Output mos are done. No way back for this board. Also . Does your mh-m18 support atpx or other codec. Better then sbc.
?
Sloppy soldering or chip breakdown? Try 12v. Use a trash speaker to test.
Without a speaker, each output has 1/2 power supply. I met reports about the short circuit of the output filter capacitors.
No idea about the ticking sound, sorry.
But I have the same board and IN- and PWR- are meant to be shorted together. They're connected by the ground plane on the back side of the board.
The issue is likely that OUT- is shorted to GND so check closely for bad solder joints etc, but I guess the fact that it worked for a bit means the chip is kaput.
Would it matter if the BT module sees the input from the 3.5 jack? i.e. could you connect pins 1,2 and 3 on the switch together and just power the BT on and off to prevent voltage spikes, clicks and pops?
The other option would be if you're going to get another board to replace this one, just get one that has BT and a 3.5 jack already
But I have the same board and IN- and PWR- are meant to be shorted together. They're connected by the ground plane on the back side of the board.
The issue is likely that OUT- is shorted to GND so check closely for bad solder joints etc, but I guess the fact that it worked for a bit means the chip is kaput.
Would it matter if the BT module sees the input from the 3.5 jack? i.e. could you connect pins 1,2 and 3 on the switch together and just power the BT on and off to prevent voltage spikes, clicks and pops?
The other option would be if you're going to get another board to replace this one, just get one that has BT and a 3.5 jack already
