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Technics ST81

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    Technics ST81

    3 months ago I found a mini system consists of ST81 Technics audio tuner+amplifier. The problem is that controls communication is done through special cables, in my case a 20-pin ribbon cable that I miss and so can not check if the devices operate.
    http://www.ebay.co.uk/itm/Technics-S...-/121209656017
    I tried from the beginning to contact Panasonic, suppliers on AliExpress or even on eBay. Unfortunately, I did not receive a favorable response.
    So I decided to consult the service manual and to dismantle the tuner for a complete visual inspection and all was OK.
    I made 20 of about 20-25cm long thin cables and tried to connect them. That proved to be a nightmare, because not all the wires were connected, and that was difficult to detect.
    ****
    Since the only way to ensure firm contact was to stick the wires on the PCB, I decided to do it today. So I lost 2 hours to prepare wires, solder them on the tuner PCB then used a glue gun to isolate with silicone the uninsulated ends.
    Then I soldered wires carefully on the amplifier PCB checking their order and finally I connected the device to the AC power outlet carefully.
    The good thing is that I managed to power on the device and after several minutes of trying the sound start on the radio.
    Now I encounter two problems. The first is that the device works with 6ohm speakers, offering a power output of 2x45W DIN / 2x60W RMS, and I have 4ohm speakers. What risk is if runs below 50% of the power amplifier?
    The second thing that worries me is the type of wires used to connect directly to the two PCBs, that some are single line, 0.5mm diameter, others are multicore, all around 0.5mm diameter - cooper core.
    How matter thick of wires or if are single line/multicore?
    Does it matter to the proper functioning of the system?
    Thanks
    Last edited by alindumitru46; 07-10-2016, 09:06 AM.

    #2
    Re: Technics ST81

    Sorry because I forsaken the forum.
    Since a month ago I solved the problem for now. I took 20 pin plugs and solder long multifilament wires, because the monofilament wires pulling away 7 traces from the board.
    Mea culpa, I was warned by @stj that these seams should be done carefully, otherwise many wires can flies with traces...
    That being said, the toy sounds perfect with a pair of SONY speakers, 2x60W at 6ohm (my luck).
    I have to buy 4 bars with 10-pin and 20-wire plug mother/mother to rebuild like the initial setup.

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      #3
      Re: Technics ST81

      Originally posted by alindumitru46 View Post
      Sorry because I forsaken the forum.
      Since a month ago I solved the problem for now. I took 20 pin plugs and solder long multifilament wires, because the monofilament wires pulling away 7 traces from the board.
      Mea culpa, I was warned by @stj that these seams should be done carefully, otherwise many wires can flies with traces...
      That being said, the toy sounds perfect with a pair of SONY speakers, 2x60W at 6ohm (my luck).
      I have to buy 4 bars with 10-pin and 20-wire plug mother/mother to rebuild like the initial setup.
      At least you got it working. Good for you,

      Comment

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