Mission Cyrus dAD 7: Missing solenoid and lid detection problem

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 resistor. 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.

6 comments on “Mission Cyrus dAD 7: Missing solenoid and lid detection problem

  1. Hello from Poland, Europe
    Excellent job Mark. Few days ago I,ve bought a same Cyrus with similar problem than You. Could You tell me (If You remember, of course) what is exactly soldering point of capacitor form photo and what is symbol of transoptor, bacause someone change a transoptor before and I think it’s wrong.
    The website still haven’t any service manual fot this Cd player.
    Best Regards Michał Polska

    • Hi Michal,
      Thank you very much!
      So if I understand correctly the cd player you bought suffers from the same issue that the lid-close-sensor is not working. I did not solder a capacitor on the board, but a resistor.
      I cannot recall exactly which solder joints I used to place that resistor. I followed the trace from the photo transistor back to one of the pins to the flat cable connector.
      You could also place the resistor directly to the pins of the photo transistor on the other side. The other wire on the pin should then be connected to ground (Should be ground based on the solder joint that is connected to the negative lead of the yellow-ish tantalium capacitor.)

      To explain a bit more how this circuit works: The photo transistor and a SMD resistor are placed in series on probably a 5 volt supply line. The photo transistor is on the 5v line whereas the resistor is connected to ground.
      This results in a voltage divider where the voltage over the resistor is controlled by the light hitting the photo transistor. Based on the equivalent resistance of the photo transistor the voltage is divided by this formula (calculated with 5v):
      Vr = Vdd / (Rtr + Rs) * Rs

      Explanation:
      Vdd = supply voltage (probably 5v)
      Vr = the “output” voltage over Rs
      Rs = the series resistor in Ohms
      Rtr = the resistance equivalent in Ohms (is not really measurable out of the circuit)

      In this case the Rs was too high, so by putting an additional resistor in parallel to Rs we can lower the resistance which results in a lower output voltage when the phototransistor is open.
      This is probably caused by degradation of the photo transistor the voltage divider doesn’t.

      Hope this shed some light on this principle so that you can project this theory on your Mission Cyrus cd player.

      Kind regards,
      Mark

  2. I have recently bought an used DAD 7 player. The player plays CD well, however, the auto door does not function. I opened it and tried to check it and found all parts are there. Any chances I can fix it like yours too. Thanks. Eddie (Hong Kong)

    • The reason that my cd-player was missing the solenoid was probably because it was burned out or in some other way broken. This could also be the case with your cd-player. If you’re lucky it’s not the solenoid itself but something in the driver circuit, like a transistor. Transistors are easy to find and in this case could also be replaced by an alternative type. When the solenoid is broken, it’s way more difficult. I don’t know how experienced you are in repairing equipment and what kind of tools you have availble, but let’s assume you do have a multimeter and know how to use it.
      First thing you could do is disconnect the solenoid from the PCB and measure the resistance of the solenoid. It should be somewhere between 10 and 1000 ohms. If it’s broken, it will measure an infinite resistance. If it measures a very low resistance, like 2 Ohms, it’s probably burned short and will most likely also damaged other parts that drives the solenoid.
      Next thing is to check if there is a voltage supplied to the solenoid connector on the PCB when you press the eject button. That voltage will be supplied only for a few seconds. I can’t remember how high that voltage should be, but should be higher than 12 volts.
      Remember that when you do this, parts of the cd-player contains very high voltages! You do this all at your own risk.

      If you’re not that familiar in repairing audio devices, It might be best to bring it to a repair shop in your area.

      • Hi Mark,

        Excellent work thank you, I have a dad 7 and it has the lid detection problem. Would it be possible to share the schematics so I can hopefully get mine fixed ?

        Many thanks

      • Thank you very much, Jin.
        I thought that I had the schematics and figured out how the detection works based on that, but it seems that I did not.
        Apparently I just figured it out using good old reverse engineering. (I will update the text in the article).

        What I did first is I measured the voltage across the LED in the optical switch. While every LED will be driven using a series resistor, the voltage should be divided between the two.
        Since I measured somewhere between 1.1V and 2.5V over the LED, I could assume that is was emitting light.
        Next is the receiver part in this optocoupler like device. This part usually is a light sensitive transistor with the base wire missing (because the light will act as base).
        This transistor is usually a part of a voltage divider with a series resistor.
        The point where both devices are connected, will be used as a digital signal for a micro processor or digital circuitry to act upon.

        Try to find that point, measure the voltage where the lid is closed and where the lid is open. That voltage should differ sufficient to create a distinct digital High or Low. It depends on the type of digital gate that senses this level whether it will properly detect if the lid is open or closed.
        When using TTL signals (5v rail)… under 0.3v should be considered LOW and above 2.7v HIGH.

        Hope this helps you a bit. Good luck repairing your cd-player!
        Regards,
        Mark

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