I’ve bought a defect Mission Cyrus dAD 7 toploader CD-player.
The problem was a broken solenoid for opening the lid of this top loader CD-Player. The bad thing was that the previous owner already had the solenoid removed. So all mechanical parts and even the solenoid were missing.
So this all needed to be redesigned.
I’ve found a solenoid that could work and figured out a mechanism so that the lid will be opened an inch or so. Enough for the user to open up the lid further until it locks onto a magnetic and will stay up.
Unfortunately this was not all. The detection of the lid was done by an optical switch sensor, but that din’t work. The circuit could detect if the lid was closed or open.
Since I had no schematics for this cd-player, I had to do some reverse engineering to figure out how this circuitry works. I tested the LED and the light pickup transistor.
They both did work, but the change in voltage was not enough to have a distinct 1 or 0 binary signal.
By lowering one of the SMD resistors this should work, but soldering
SMD surrounded by a lot of plastic components isn’t ideal. So I came up with the following solution:
A resistor placed in parallel over the SMD transistor. I calculated a value of 2k7 Ohms. Now the light switch correctly gives a digital “0” or “1” depending on the position of the lid.
So there it is, working perfectly fine again.