Remote control adjusts volume up and down too much for low volume listening

[gghodg]

Hi Folks,

When I tap the up or down volume button on my remote control the amp volume jumps up or down too much for low volume listening. One workaround has been to lower the input volume, unfortunately that is not an option when listening to vinyl.

I have solved this issue by adding a resistor to the volume motor circuit. Less power to the motor yields a slower motor rotation speed. My concern is does adding a resistor cause issues with the IC (L293DNE) that drives the volume motor. I've thought of changing the input resistance to the IC but don't have SMD or resistors in that Ohm range. At least for now I can enjoy late night listening at low volumes. Any guidance and/or feedback is appreciated.

Motor coil resistance ~ 22 Ohms
Voltage at coil when pushing volume control button +/- 4.4 Volts DC
Added resistor ~ 47 Ohms (0.4 mW)

Schematic attached - Volume motor circuit circled in red.

 

[jan.didden]

It's very unlikely that there's anything wrong in the vol motor circuit, it can't just speed up. Most likely is an issue in the controller. It uses internal timing loops and gives out signals an pulses to the motor that determine the speed. mot_vol, pin 30.
Will be hard to diagnose and fix.

 

[gghodg]

Thanks for your reply. I don't think there's an issue with the motor circuit. IMO It was implemented to run the motor too quickly for this amp. Does adding a resistor at the output cause any issues with L293DNE? I'm not seeing anything that sticks out... this is my first time making this type of modification... Adding 47 Ohm has slowed the motor down enough .

 

[Bonsai]

I don’t think adding the resistor as you have will cause any problems - you should be good to go.

 

[gghodg]

Ok thanks.