How a cd drive ejects and loads a disc

Thread Starter


Joined Sep 17, 2023
Hi all. I'm not sure I'm posting on the right forum and please accept my apologies if I am.
I'm new to electronics and I need pointing in the right direction to solve a problem I have with a "for fun" escape room type project I'm working on.
One module within this project uses 3 ldr's linked through 3 relays to supply voltage to open a recycled cd rom drive. The drive just needs to open when 5vdc is momentary applied to the eject mechanisms dc motor and then close when voltage is reapplied.
I have stripped out the main pcb and optical lazer parts of the drive, leaving the tray mechanism dc motor and it's connected pcb installed and when voltage is applied to the motor the tray opens faultlessly and reverse the polarity and it closes. But here's my problem. I need the limit switches to stop the motor when fully open or closed and the mechanism by which the polarity is swapped (these I believe are done in the small pcb attached directly to the dc motor) but I have searched high and low and gave my multi meter repetitive strain injury! But I can't work out how it works!!
So I thought if someone who knows more than me (not difficult) can point me in the right direction.
Kind regards


Joined Nov 29, 2005
The limit switches can be by optointerrupters, microswitches, current surge detection, step counts, time, a combination of those...
Follow the traces for the tray motor feed and find data sheets for the integrated circuits involved if you cannot find the unit schematic.