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Resurrection of a Philips CD555 Sound Machine

Discussion in 'Tech talk' started by Virgil Gheorghiu, Apr 1, 2017.

  1. Virgil Gheorghiu

    Virgil Gheorghiu New Member

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    Ok, like I suspected, the Error Detection and Correction IC (SAA7020) on the decoder PCB, was also toast. I've replaced it with the one from CD150, and lo and behold, my TOC is read and 20 appears on the LCD (20 is the number of tracks this test CD has :p). So, now I can go about trying to play something and bring this unit into factory parameters. Whew, that took a bit of debugging!

    (I'm so happy it read TOC I didn't even try to play something, so technically I'm not out of the woods just yet.)
     
    Last edited: Jul 17, 2017 at 12:06 AM
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  2. Jorge

    Jorge Active Member

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    Good job!! Congratulations and do not forget to post some photos of the beast!
     
  3. Jorge

    Jorge Active Member

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    I have to substitute a driver chip on Sony D-7, already bought two "donors" but not quite sure how to safely desolder them: low-melt QuickChip or with hot air/desoldering station. How did you do yours? Thanks!!!!
     
  4. Virgil Gheorghiu

    Virgil Gheorghiu New Member

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    Hi, Jorge

    News update: everything works! This morning I was able to record from the CD to the cassette player. CD playback and the resulting recording are fabulous, and make me smile. Now I have to just do a bit of wrap-up and factory spec checks, like mentioned.

    The Philips has no SMD IC's, all are through-hole DIP. There are tons of resistors, transistors and capacitors that are SMD, but no IC's, so it was a simple walk in the park with my Weller and a desoldering pump. The SAA 7020 is a 40-pin IC, so it took a little time to do. That being said, I have replaced millipede :) SMDs before. You can use a desoldering wick (braid), a pump and lots of patience. A good soldering station with a sharp tip, good solder and hot air would get you far. But above all, patience. Lots of it.
    A sharp 0.5mm tip (preferably bent) on a quality temperature-controlled station is a good place to start things with.

    Hope this helps. Let me know if you need assistance.

    Thinking about this a bit, I got a crazy idea:
    1) If you are _absolutely sure_ the old IC is toast, use a wire cutter or similar to simply cut its old pins from the packaging, which you can subsequently easily remove with a regular soldering station. A Dremel with a metal cutting wheel may work as well, but be careful of its vibrations and don't slip the wheel into the PCB for obvious reasons (¯\_(ツ)_/¯).
    2) You'll need to desolder the replacement IC from its PCB; presuming you don't need the rest of the PCB you can make this a destructive operation as well; all you're interested in is the chip, not the PCB, so trace errors are allowed when lifting the pins off the PCB.

    That being said: if you have donor PCBs, why not replace the whole PCB? Maybe fixing the donor PCB is not that labor intensive...
     
    Last edited: Jul 17, 2017 at 8:38 PM
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  5. Longman

    Longman Active Member S2G Supporter

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    I would recommend desoldering wick over a pump as it is all too easy to pull pads off the board.
    Just be aware that desoldering wick has a shelf life especially once it has been opened.
    The sort we buy at work come as five vacuum packed in a tube a bit like Pringles, and for exactly the same reason.

    How you remove an SMD IC depends on whether you want to reuse it. If you are sure it is faulty you can cut all the legs by the body
    then remove them one by one. If you want to reuse it one technique is to lift each leg one by one - Once the IC is off you can bend them
    back to the original position. In either case good magnification is a must.

    If you want to reuse the IC but aren't bothered about keeping the board you can heat the back of the board with a heat gun until the components fall off if gently flicked. I used to do this with duff computer motherboards.

    p.s I have only used these techniques on Fibreglass boards. Paxolin or Flexis might need different techniques
     
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  6. Jorge

    Jorge Active Member

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    Million Thanks, guys!!!! So, heating the chip is not as safe as internet pseudo-knowledge makes you believe... and my tests with low melting point QuickChip were a mess!!! Will go slow'n'steady one-by-one on the chip! Mano a Mano!!! ;-)
    @Longman : where do you buy those vacuum-sealed wicks? I always saturate mine with a soldering paste from Cardas but the wick does get bad over time...
    Anthoo, I feel real good about myself that I asked!! Thanks again! :wave:
     
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  7. Virgil Gheorghiu

    Virgil Gheorghiu New Member

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    Hi, all

    Here is a little movie of ‘the beast’ as Jorge said. It’s still not done (and I expect something to break at any moment :)) but for now it shows a bit of what this machine is capable of and why I love it so much...

    Thanks,
    Virgil

     
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  8. Longman

    Longman Active Member S2G Supporter

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    http://uk.rs-online.com/web/p/desoldering-wicks-braids/5086346/
    You could probably find the same from Newark, Mouser or DigiKey but it's probably not appropriate for anywhere but a production environment where the wick gets used regularly.

    I also found a thread on a different forum all about desoldering. I hadn't thought of the dipping in flux idea.

    https://www.vintage-radio.net/forum/showthread.php?t=100612
     
  9. Jorge

    Jorge Active Member

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    Looks very nice!! As a hater of dual cassette "things", be it bboxes or decks, I like the idea of using extra space for CD. Unfortunately, all such bboxes are from soapbar-style era. This one looks very 80-ies, whe way I like them!
    The tweeter on D555, is it horn-loaded piezo crap, as on my D8444? I am thinking about changing mine for a ribbon tweeter ($12 from PartsExpress, 6 Ohm), what do you think??
     
  10. Virgil Gheorghiu

    Virgil Gheorghiu New Member

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    Hi, Jorge

    The speakers have proper low/midrange and highs coil driving units with a passive crossover built-in.
    They're made in Belgium (for or) by Philips. Here are some pictures I took when I cleaned them.
    The cabinets are made of wood and filled with wool. There are no bass port holes.

    I like the unit's design a lot because it's very ergonomic (buttons are clearly laid out, in similar order between the CD and the tape deck) and clean. Like you, I prefer the more square-ish look over the soapbars from the '90 and later. This one is manufactured on Oct 2nd 1987.

    As for the ribbon, I don't know if it's worth it (in a portable, I mean). Any proper tweeter will sound more natural than a piezzo driver. You need proper math, a good ear and a spectrum analyzer to get the sweet spot of the crossover built in such a way (repeatable) so the investment is worth it.

    Hope this helps.
    IMG_0432.jpg IMG_0423.jpg IMG_0424.jpg
     
    Last edited: Jul 18, 2017 at 1:10 PM
  11. Jorge

    Jorge Active Member

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    My bad, D555 is a real thing! I want one!!!!!
    D8444 does not even have a xover, piezo gets the full signal. Most probably I am not going to mess with my Philips, bought it for a repaint challenge at another thread here (well, it was not a challenge until I put it this way).
    Looking at D8444 I am getting mixed feelings about repaint: in black/silver it looks pretty decent. But Im gonna paint it anyway, while my plastic jets modelling hobby is on hold. Feel free to admire my beauties at square-2.com ;-)
     
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  12. Virgil Gheorghiu

    Virgil Gheorghiu New Member

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    I spent quite some time on your website admiring the jets. I used to do that as a child and loved every minute of it. Don't ever stop!
     
  13. Jorge

    Jorge Active Member

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    Very kind of you, Thanks!! I stopped for now because I cannot force myself to sell any and there is only so much space around the house, all filled with my wife's artwork (allois.com). For some reason letting restored Discmans go (Discmans is my tiny specialty) is easier for me; as you said, maybe because of the Childhood connection thru jets...
     

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