How do you remove the 6 pin volume pot from a tda7297 amp?

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#2
Locate the minimum volume position pin...this will be ground. Install one each 47K or 51K resistor between ground and the other two pins. Install one resistor for each channel.

Can't find which is ground...
Install the resistor(one per channel) at the far points and short the middle point to the either. In one condition, it will be max and the other, min. Short the two points of interest.

3 points in line are for one channel.

Don't have 2X3 points, show your pot.

Gajanan Phadte
 
#3
HzMeister said:
Does anyone know how to remove the 6 pin b50k potentiometer from a tda7297 amp so that it's at full volume?
Click to expand...

Just desolder it (use a pump or desolder wick); remove it and short the input pad to the wiper pad on the PCB. For each channel.
The wiper pad will be most likely the center one, and the GND-pad is the one in the GND-area of the PCB. The remaining one is the input pad.

Alternatively, you could make a short between input and wiper on the PCB. The pot will remain beween input and GND as a fixed resistance of 50k.

Why would you need to remove the pot, btw? Mine sounds OK, with pot...


YMMV
 
#4
Thanks for the replies. I had an idea it would something as easy as this but wanted to be sure.

gmphadte, is there any reason to go with 47k or 51k resistors specifically? Could it not be 50k,100k,or even 330k resistors?

fastfolkert, my amp sounds fine with the pot too but I don't really need it since I adjust the volume at the source(usually computer). A couple of high quality resistors will hopefully sound better and definitely be more reliable.
 
#5
Just to be clear:

After removing the potentiometer there are three holes in one channel: input - output - ground (in that order)

I would connect the input to ground with a 50k resistor. Then I would short the input and output with a bare wire.

Same for the other channel.

Is that correct?
 
#6
No, you don't need the 50k resistor; the chip itself already has an input impedance of 30k.
Just connect input and output (for both channels) and you're set. Remember the GND connection is most likely the one which is soldered to the "GND plane" of your PCB. That one remains unused after removal of the potmeter.

YMMV
 
#7
Thanks for the clarification. You are very right. I took apart the cheap pot to see how it works and there is no resistance at both max and min so a solid wire between input and output will set it to max. I might still experiment with using using smaller value resistors to tweek the volume lower if needed. For example, a 25k between input and output and another 25k between ground and output to simulate the pot at the halfway point. I hope my logic is sound as I'm still learning.
 
#8
It depends a little what you want to do with the amp:

Some people just remove the pot and connect the input signal directly to the input of the amp.
This means the amp is always at "max volume"; meaning you have to control your input signal carefully.
You *may* use a 50k or 100k resistor from signal to GND (on each channel) , but since the chip-amp has an input impedance of 30k; that extra resistor is not needed.

Other people remove the cheap pot, and use a new, higher quality pot instead. You don't have to solder it to the PCB again; you can use short wires to connect the pot to the PCB and mount the pot in the frontpanel.
A stereo 100k log (or audio-) pot will do.
BTW: your original pot is most likely a log pot; this means when it is set halfway; the resistance ratio is NOT 50/50 (more likely 10/90)

YMMV
 
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#9
That's true. Unfortunately, most of the tda7297 amps on ebay come with a low quality b50k pot which is linear. It's one of the reasons I wanted to remove it - after the halfway point to max it made almost no difference. The a50k is the log/audio version that would be better suited to this amp.

For anyone that doesn't need to adjust the volume, I highly suggest you remove the pot.The bare jumper wire that I have installed now definitely improves sound quality and reduces noise. Even without the upgrade caps from mouser, removing the ac diode and volume pot made a significant difference. With upgrades, this amp will be ridiculous.

Thanks again for you help fastfolkert.
 
#12
fastfolkert said:
It depends a little what you want to do with the amp:

Some people just remove the pot and connect the input signal directly to the input of the amp.
This means the amp is always at "max volume"; meaning you have to control your input signal carefully.

Other people remove the cheap pot, and use a new, higher quality pot instead. You don't have to solder it to the PCB again; you can use short wires to connect the pot to the PCB and mount the pot in the frontpanel.
A stereo 100k log (or audio-) pot will do.
BTW: your original pot is most likely a log pot; this means when it is set halfway; the resistance ratio is NOT 50/50 (more likely 10/90)

YMMV
Click to expand...

very helpful comment, have 50K audio pot, what functional difference with 100K?
 
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