Hello everyone!
Recently i scored a CD mechanism with 3 CD changer from an old sony audio system.
I started reverse engineering it yesterday, using it's datasheet and some coffee and here's what i got:
The CD assembly itself has integrated all the control logic, this control logic has 2 main chips a CD controller (focus, tracking etc.) and an MP3 decoder. I hacked into it's connector, got all the wires hooked up, ready to roll.
The mechanism is relatively simple:
it has 2 Chip Enable pins (took me some time to figure this out) CD_CE and MP3_CE
SPI interface (labled D0; DI; CL)
a mute pin
analog audio output
after getting to this point i realised that i don't have a clue on how to talk to the main chips 
In theory should be this way:
CD_CE -> <> after feedback either plays or MP3_CE + some commands
I feel lucky that it has SPI and not other unknown interface 
The chips i'm talking about are:
LC78684E - MP3 Decoder
LC78646E (-E?) - CD chip
and these 2 were controlled by LC876780B main chip (with integrated VFD driver?)
Here are the useful links:
http://www.datasheets360.com/pdf/-7041274271229766015 - Main chip
HTTP 301 This page has been moved - MP3 decoder
HTTP 301 This page has been moved - CD chip (Japaneese datasheet was all i could find, seems to be very basic datasheet)
SONY HCD-GX45 RG440 VER-1.2 Service Manual download, schematics, eeprom, repair info for electronics experts - Service manual of the audio system it came from
Could someone help me to control this thing? Anyone has some info about it's commands? because as far as i know these aren't programable