How to connect mute switch to TDA7297 amp?

Thread Starter

big10p

Joined May 25, 2013
35
Hi

My electronics knowledge is minimal I'm afraid, so I have come here hoping for some much needed guidance. :)

I have this little amp and am trying to figure out the best way to wire a mute toggle switch to it. I was just going to wire the switch to either the amp power source to simply switch the amp on/off, or to the two +ve speaker wires, but now realize both options are probably bad ideas.

I see from the datasheet that the TDA7297 has a MUTE pin. With my limited knowledge, it seems removing the voltage to MUTE (pin 6) is what I need to do? I'm really looking for a dummies guide to wiring the switch, and if caps/resistors are needed (to eliminate on/off popping), what value they need to be.

Looking at the PCB, the MUTE and ST-BY pins are tied together, so I'm unsure if what I want to do is possible, without cutting/patching traces. Couple of close-ups of the PCB below. All help with this greatly appreciated!

TDA7297parts.jpg

TDA7297solder.jpg
 

sghioto

Joined Dec 31, 2017
5,390
it seems removing the voltage to MUTE (pin 6) is what I need to do?
Correct, but not possible as you said without modifying the board. Best operation would be to separate the two pins, however you can connect a switch from the two pins (6,7) to ground. Close switch to mute.
SG
 
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Thread Starter

big10p

Joined May 25, 2013
35
Correct, but not possible as you said without modifying the board. Best operation would be to separate the two pins, however you can connect a switch from the two pins (6,7) to ground. Close switch to mute.
SG
Thanks for the replay.

Just so I'm clear on this, does that mean I can just solder a wire to pin 6 (or pin 7, since they're tied) and connect it to one terminal of a SPST switch, and connect the other switch terminal to ground?
 

Ya’akov

Joined Jan 27, 2019
9,152
Thanks for the replay.

Just so I'm clear on this, does that mean I can just solder a wire to pin 6 (or pin 7, since they're tied) and connect it to one terminal of a SPST switch, and connect the other switch terminal to ground?
You can, but you will be turning off the amp, not just muting it, and you will probably get pops as the datasheet warns.
 

Thread Starter

big10p

Joined May 25, 2013
35
Ah right, so this would be basically the same as just putting a switch on the +12v input wire?

Also, there's a 10uF 25v cap connected to the pins - won't this prevent, or at least lessen the popping?

If needs be, I'm prepared to do a bit of trace cutting/patching etc., just as long as I can be totally clear on what's needed to be done.

Thanks.
 

sghioto

Joined Dec 31, 2017
5,390
If you want to try modifying the board then:
As stated in post #2 it would be best to separate the pins.
Cut the trace between pins 7 and 6.
Cut the long trace from pin 6 to the 10uf capacitor.
Connect a jumper from the 10uf back to pin 7.
Connect a SPST switch between pins 6 and 7.
SG
EEE TDA7297 mute mod.PNG
 
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