Man.....This is drivin' me nuts! I've got 2 of these stereos on my workbench that I've been tinkering with. Thier guts are hangin'out all over the place. And I cant get it to work! I figured out(I think) how he cuts the radio signal. There are 5 wires going to the cassette deck. RD,RD/WHT,ORG,WHT, and BRN. The RD and RD/WHT go to a micro switch that is Normaly Closed. They go nowhere else. The micro switch is tripped and opens up when a cassette is inserted, breaking the circuit. This disables the radio signal, closes the other half of the micro switch, and sends power to the cassette deck. Then the cassette signal travels down the 3 remaining wires to the amp.
So I added a switch to the RD wire. When thats tripped, it cuts the radio. The display on the front changes from a radio station to the clock. Just as it should when a tape is inserted.
I then spliced a 3.5mm stereo receptacle into the 3 other wires. And plugged in a portable CD player. Nothing. I hit the switch, the radio cuts out, the display changes, but no sound from the CD player. WTF? There are ONLY 5 wires from the cassette deck to the rest of the radio. I have tried those 3 wires in every combination on the plug.
This guy is doing something simple to make this work. Hes modding too many different radios for it to be too complicated. But they're all GM Delco radios. So there must be something simple and something similar in all of them.
I've got 1 radio from the '87 celebrity, and another from a '89 buick century. They look the same on the outside, but the cassette decks are built different. They are wired the same, and look similar, but use some different components. Whats crazy is the '87 looks more high tech than the '89!
I found a 3.5mm plug that has the SP/DT switch built into it. That way when the plug is inserted, it throws the switch at the same time. But I'm not getting one of those until I can get the prototype to work first.