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How to disable CD player sensors?

kerryland

Mar 7, 2022
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Mar 7, 2022
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I have had partial success modifying a small all-in-one hifi without aux-in (a Panasonic SA-PM21) to support a Bluetooth receiver. It is successfully playing Bluetooth audio, but only when I have a CD inserted and press "Play".

Clearly there is circuitry in place that kills amplification until the door is closed and "Play" has been hit, but I need help bypassing that logic because the CD player mechanism is loud, and it seems very silly. I have been doing a lot of reading, but am very inexperienced.

In the attached extract from the schematic you can see the "CN801" pins that come from the CD part of the system. I have successfully wired the Bluetooth component L, R and GND pins to CM801 pins 17, 15, and 16 for the audio, but now I suppose I need to do something with "LD_SW" and "REST_SW" and "CD OPEN SW", but what?

As an aside, I also don't understand why everything from CN801 connects to one black line down the right of the page.

Thanks for listening. I have had great fun with this project, but am a little stumped.
 

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kerryland

Mar 7, 2022
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Mar 7, 2022
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To clarify a little more: "LD_SW" and "REST_SW" and "CD OPEN SW" are obviously switches, but they are each just one pin -- how does the circuitry know whether the switch is open or closed? Where is the "other side" of the switch? How do I fake open or closed?
 

Tha fios agaibh

Aug 11, 2014
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Aug 11, 2014
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That black line on the right is not one wire. It is a buss of all those individual branches that go to the rest of the circuit. (Servo circuit)

You see one pin, but there is more to the circuit.
For example, the Reset switch comes from the black line on the right (think of it as a conduit of wires) and when it's made the input on the left (cn801) turns low (0v).
When the switch is open the pull up resistor R805 makes it go high (5v).
 
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