Sony SPP-Q120 - How to Increase Volume (cordless phone)
Sure, this is an old model, but these principles could apply to increasing the volume on many brands and models of cordless telephones. A little experimentation should work. Have fun.
The SPP-Q110 (similar to SPP-110 & SPP-120) uses a Toshiba TB31223F IC to process audio, and that IC is similar to the TB31224F, which the SPP-110 uses.
Pin numbers & values may vary, but here's how I fixed mine:
I followed the traces from the speaker connector back to the IC. Positive goes to pin 20, and negative goes to pin 18.
Coming out of pin 17 is capacitor C110 (.047uF) and that connects to resistor R113 (22K) which then connects to pin 18, comprising the gain control for the audio output amplifier.
I simply changed R113 from 22K to 6.8K and that did the trick.
I used a 1/6th-watt leaded resistor and had plenty of headroom to mount it vertically (upright) with the leads snipped about 1/16" long.
You can download the schematic for the SPP-110 schematic here:
The SPP-110 schematic shows a volume control switch, which the SPP-Q120 does not have. Looking at that, it was easy to reverse engineer.
This phone was just too quiet, so I had to make it louder. Sounds great now.
Keywords SPP-Q110 SPP-Q120 SPPQ110 SPPQ120 SPP-110 SPP-120 SPP110 SPP120