CD player Technics SL-PG490 (SL-PG490E-K) repair, CDM12.1 (VAM1201) "no disc" (fixed)

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  • Chungalin
    Badcaps Veteran
    • Jul 2014
    • 422
    • Spain

    #1

    CD player Technics SL-PG490 (SL-PG490E-K) repair, CDM12.1 (VAM1201) "no disc" (fixed)

    This was supposed to be a routine pickup replacement, as it had already been cleaned a few months ago and now it's not dirty (neither outside nor inside prism/mirror). It throws a "NO DISC" message with very little tries. It uses a Philips CDM12.1 mechanism, also known as VAM1201.

    Some time ago I ordered 5 pickups from AliExpress (shivers). As they came without mechanism, the price was good (this is the common part of all AliExpress stuff) and pictures looked decent. They arrived promptly and as described but couldn't try any, because I didn't have any pending repair requiring this pickup. I left positive feedback.

    Today I use the first one with this Technics and... it doesn't even do focus movement, I mean, the simple act of moving the lens up and down trying to focus the disc surface. This is something that even a pickup with dead laser or sensor does, because the driver tries to focus even if nothing is received from laser sensor.

    I disassemble the pickup again and check the coils continuity. The Tracking coil is OK (about 18Ω) but the Focus coil is open. Upon visual inspection I detect that the flexible wire is cut at the point shown in picture!! (picture is NOT actual pickup but the original one, I won't disassemble again just to take a picture, sorry). Pickup looks new, not refurbished, but this defect is quite revealing. Other wires seem tight. From left to right, Tracking coil is at wires 1 and 4, while Focus coil is at 2 and 3.

    I decide to solder the loose wire, although I can see that these wires are not "soldered", but twisted around a pin and then seems that they melt the copper with some high voltage discharge (?). I don't understand why they have to do it this way, it has to be some reason. I've soldered wire to its pin and now everything works fine. For how long?
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  • Longbow
    Badcaps Veteran
    • Jun 2011
    • 623
    • USA

    #2
    Re: CD player Technics SL-PG490 (SL-PG490E-K) repair, CDM12.1 (VAM1201) "no disc" (fi

    Originally posted by Chungalin
    I can see that these wires are not "soldered", but twisted around a pin and then seems that they melt the copper with some high voltage discharge (?). I don't understand why they have to do it this way, it has to be some reason. I've soldered wire to its pin and now everything works fine. For how long?
    Because of heat. It is like soldering a thermal fuse.
    Is it plugged in?

    Comment

    • Chungalin
      Badcaps Veteran
      • Jul 2014
      • 422
      • Spain

      #3
      Re: CD player Technics SL-PG490 (SL-PG490E-K) repair, CDM12.1 (VAM1201) "no disc" (fi

      But these aren’t fusable wires. They just need to be very flexible to stand the lens assembly oscillation as it tracks CD surface as it spins. In this sense, they’re similar to speaker wick cables that go from the contact tab to the cone.

      And, apparently, nothing bad has happened when I’ve soldered it as any cable.

      Comment

      • Chungalin
        Badcaps Veteran
        • Jul 2014
        • 422
        • Spain

        #4
        Re: CD player Technics SL-PG490 (SL-PG490E-K) repair, CDM12.1 (VAM1201) "no disc" (fi

        I’ve just repaired another CDM12.1 / VAM1201 mechanism from a Philips CD163/00 CD player. In this case, tracking coil was open (2 outer wires). I’ve soldered the cut wire to the pole, trying to use as few solder as possible. It works!

        BTW, no return from the other repair.

        Comment

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