How to check and adjust laser current in 1983 Philips / Marantz players ?

Discussion in 'Digital Sources' started by david winter, Jul 1, 2018.

  1. david winter

    david winter Classical music lover. Subscriber

    Messages:
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    Location:
    Paris, France
    Hi,

    I have three early CD players at the moment:
    - Philips CD100 and CD300
    - Marantz CD73

    I recaped the CD100, and did the power supplies of the other two.
    What It's like to know is how I can check and adjust the laser current on all three.
    Are there tutorials for this ?
    So far they play but are extremely sensible to the tiniest vibration. Moreover the CD300 and CD73 won't always load the CD straight, so something must be weak somewhere.
    Any hints appreciated. Thanks !
     

     

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  2. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    Don't!

    The laser is rarely the cause of performance issues like that, and turning up power to the laser will often end up killing it. These lasers will otherwise last much longer than other brands seem to, provided you don't cause that premature death.

    Did they play before you recapped? Same issues before and after? Did you replace ALL the electrolytics, or?

    Short answer on adjustment is you need the manual, need to understand the process, and you need a laser power meter. And, you should first fix any other issues as the laser is very rarely responsible for causing disc read problems on these early Philips units. Don't touch it would be my recommendation. I have serviced my own Sony CD players in the past and will again if needed, and I own a power meter, but I prefer to send my Philips-based stuff to another tech friend in LA that has the expertise and experience to service them correctly without breaking them in the process.

    If the discs aren't loading straight, you definitely have other issues to address first.

    John
     
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  3. david winter

    david winter Classical music lover. Subscriber

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    They didn't work before recaping (mostly because they all had the same dry blue caps in the power supply).
    The CD100 works better, from memory I did a full recap (and hope I didn't leave any electrolytics looking like film caps or so). It also had a broken electromagnetic switch at the audio output.
    The CD73 didn't even spin before recaping. I don't remember if I did a full recap but I'll check.
    I also remember reading about some specific leaky capacitors on the laser circuit board. Can't remember which, I'll try to find again.
    I didn't touch the laser adjustments. I would if I had the proper test equipment.
     
  4. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    Yes, those blue Philips caps are a known problem area. If memory serves there's a 33uf cap that's usually the one that causes the player to stop reading discs. If you left any electrolytic caps on the digital board, those would be the next step.

    Spindle motors can be cranky, platter height, swingarm motion being impeded, etc. - the mechanicals have to be correct. I'm not an expert myself but have picked up some tips from someone that is - hopefully have those details correct here.

    John
     
  5. david winter

    david winter Classical music lover. Subscriber

    Messages:
    553
    Location:
    Paris, France
    I finally fixed the CD73. It had a power supply fault in the -18V section which barely gave -7V. Don't know how it could have even loaded a CD with this.
    The culprits were two BAW62 open diodes. One of the two in series was bad, and another next to it.
    In the meantime I double checked my recaping using photos of other players, which made me discover the various versions (mine is the one with the additional Sony board over the main one).
    I even discovered that those circuits were same as in the Philips CD200. From what I saw, only the PSU pcb layout differed. The servo / audio boards seem to be same.
    Player works nicely now and indeed, is a lot more stable than what it used to be before recaping the other boards than the PSU.
     
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  6. Fredrik 1977

    Fredrik 1977 Super Member

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    stupid question maybe but did you recap the servo pcb under the CDM0-1-2 drive? this is imporant to do on these since those blue philips axial 22-33uf go bad. and the thing wont read.
    rest of the machine is important to but maybe easy to miss this?
    u probably did this.

    this applies to technics/pana players using the philips CDM-4 drive, the mainboard is made in japan with japanese caps but the cdm is european with philips caps. these players often just needs new caps on cdm pcb and they are good to go

    oh! btw i love these players! best ever made!
     
    Last edited: Jul 10, 2018

     

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  7. david winter

    david winter Classical music lover. Subscriber

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    I didn't go through this step because I have no idea how to dismantle the heavy motorized loading tray.
    Philips CD100/200 no problem, I did both already.
    But CD-73 is another story and without a detailed procedure I won't do it. But so far it plays well.
     
  8. Fredrik 1977

    Fredrik 1977 Super Member

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    Location:
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    usually that pcb is accessible by unscrewing the bottom plate. maybe not on the cd73 i have not worked on that model.
    usually there is 3 22uf caps to replace here. often they are totally dead.
     

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