Hack Digital Radio, Replace the Volume Control
Intro: Hack Digital Radio, Replace the Volume Control
Few moths ago, my mother come back from Italy and brought me a digital radio in the form of an car (Porsche Cayenne ?)
it is cool, no ?
But an issue is present, on every boot, the volume is set to 84% ... It's very loud !!
I don't understand why each FM frequence are saved into the memory but is not the case for the volume level ?
It is why i decide to try to control the volume from an external potentiometer
STEP 1: Identifying the Amplifier Chip
After i have identified the amplifier chip : an MC4863 (Dual 2.2W Audio Amplifier) i downloaded the datasheet to understan how the gain is controled
I found the following text and image in the datasheet:
The first amplifier’s gain is externally configurable, while the second amplifier is internally fixed in a unity-gainThe datasheet talk about a resistor of 20Khom to control the external gain but on the PCB i found two resistors of 67Khom ... may be to have a satured gain ?
STEP 2: Build a Dual Potentiometer From Two Traditional Potentiometer
The Chip MC4863 is a dual Audio Amplifier so that means it has two independent output signals ... which mean it require two different potentiometer in one package
I don't have one, so i build it one ...
STEP 3: Fix the Dual Potentiometer
After the dual potentiometer is done, i fixed into the car
STEP 4: Replace the 67Khom Resistors by the DIY Dual Potentiometer
I disoldered SMD resistor and connect my DIY dual potentiometer
2 Comments
makeosaurus 8 years ago
neo_xnitro 8 years ago
Thanks ;)