Creating an amplifier out of a car stereo

Submitted by Eno on Sat, 11/23/2019 - 06:08

Hi there! Glad to be here. I'm only do it myself in electronics in my spare time, therefore I'm far away from a beginner. However, that does not stop me to try to do things that are beyond me, solely because I enjoy it. These being said, please, don't dissapoint my ambition by saying that what I'm trying to do is beyond my capabilities. 

All right. I'm trying to turn my past Sony MEX BT2700 stereo into an amplifier for a much lower end, cheap Chinese car radio, which I love for how it fits to the interior of my car, has a USB slot, Bluetooth, and does not make that annoying beep anytime I remove the key from ignition, as Sony does, and it cannot be set off on older than 2011 models. 

Now, I found the post of someone who has done something like this, but the stereo that he used was different, more exactly the IC, it was slightly different than mine.

What I've got is a TDA8588AJ/R1Cu, whilst his was a Toshiba TA8272H. Here's the link to the Instructables website where he posted his masterpiece:

He has eventually separated all the components that were necessary for the IC to work, conform to the schematics of the IC that he has found on the Internet (he's also an engineer, far more superior to me in terms of diy electronics), and lastly he has cut the rest of the board, leaving untouched only a third of it, surrounding the integrated circuit, at the back of the stereo device. He said that he has managed to add a jumper link on the stand-by pin of the IC, that before it was only powered by the micro controller when the radio was on, before he "injected" signals direct to the input pins, and then he redirected the audio from the audio-out connectors to feed audio to the amp into the couple of RCA outputs on the back, and audio came out of the speakers.

The idea is that his IC seems to have, conform to the sheet, a stand-by more, which conform to the sheet of my IC, mine doesn't. 

I'm afraid to just cut the board, and hope that it will work, as my knowledge of electronics is far weaker, to start tracing the pathways ot each pin and where it should go, in order to be able to make sure that I separate the necessary part of the board, from the unnecessary one, which contains the microcontroller, the thing that will keep the amplifier from working at all, until the face of the device is put on, as a normal radio device. 

My questions are: 

1) What the connections would look like, in order to use this stereo as an amplifier, should I put the RCA out L and R of my little Chinese radio, into the RCA in L and R of the Sony stereo that I intend to use as amplifier only?

Of course, I will wire the Sony as normal, into the dashboard, and the signal radio I will wire in parallel to the Sony, only the plus and the minus, and the yellow and orange wires. 

2)What should I have in mind if I cut the Sony board, and I get no signal into the speakers? Of course, I will make sure that along the cut no copper chips will mix with each other or with solder chips, so as to avoid any short circuits. 

However, if I get no signal, should I try to wire any pin of the amplifier to the plus directly? Or to the plus coming from the ignition? 

I have an image in mind of what I should or should not have to consider, but my knowledge of 101 electronics lacks much content, and I can only put things together, on the go. 

Thanks for any insights, and helpful opinions. Nevertheless, no discouraging opinions are welcome, LOL.