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Help Reading Sony Schematic

Discussion in 'Electronic Repair' started by Degull, Jan 3, 2006.

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  1. Degull

    Degull Guest

    I've narrowed down the problem on my TV, but I need some help readin
    a schematic. What do solid black arrows with values next to the
    pointing to inputs/outputs mean? There are no units (V, Ohm
    etc.)beside them, so I'm assuming they are DC volts

    I'm pretty sure that the main speaker amplifier is defective, bu
    before I go through the process of ordering another one, I would lik
    to confirm that the supply voltage is present. On the IC it shows
    value of 21.5 with a solid black arrow pointing to VCC, can I assum
    that I should have a reading 21.5 VDC at this pin
  2. Michael Ware

    Michael Ware Guest

    That would be my assumption, in a properly functioning circuit. Check for
    general notes on the schematic, i.e. ' all values shown in DC volts unless
    specified '.
  3. Why not take a voltage reading on a part of the TV that's working
    correctly and compare it to the schematic.
  4. spudnuty

    spudnuty Guest

    Those are voltages and are DC. There will also "TP"s on these boards
    that are test points for crucial voltages.
    Could you give a more extensive description of your problem? What's the
    model #? Is there no sound at all? Is it tuning properly? Is there
    sound on the line outputs? There is a common problem with Sonys of a
    certain type where the sound just goes out or gets really flakey but
    the line output is unaffected.
    Look for "Sony KV-32TS35 No Audio" in this same forum, posted Dec 30. I
    actually had one like that and bought the part from Mats. Works fine.
    Very satisfying.
  5. Degull

    Degull Guest

    The TV is a Sony KV-32TS35. The video works fine but there is n
    audio. I tested the audio outputs at the rear of the TV with a pai
    of computer speakers and they work fine. I have been using
    schematic for a Sony KV-27TS35. The audio and tuning sections in th
    KV-27TS35 look identical to what I have in my KV-32TS35. Afte
    following the audio path in the schematics it looks as though th
    audio is split to two areas once it is processed in the SBX1637 soun
    module. The SBX1637 feeds the audio outputs at the rear of the TV o
    the A board and the main speaker amp on the B board. I'm assumin
    that because I have audio at the audio output on the rear of the TV
    the audio output of the SBX1637 must be good. I checked the voltage
    on the main amp which is a TDA2009A chip and they all match the value
    on the schematic except the for the outputs of the chip which are
    VDC (they should be 10.7). It looked as though the TDA2009A chip wa
    bad. So I managed to find the TDA2009A at local electronic suppl
    (the only one they had) and I replaced it. Damn it, still no audio?
    The new chip tested the same as the original chip with all th
    voltages matching the schematic except for the outputs which wer
    still 0 VDC. I'm wondering if I got a bad chip? It was th
    electronic store's last TDA2009A.

    I read somewhere that I should be able to test the inputs of the mai
    amp IC by using a pair of amplified computer speakers? This wil
    tell me if the audio signal is reaching the amp IC (TDA2009A). Th
    inputs of the amp IC read 1.4 VDC as shown in the schematic but I'
    not sure that means that audio is present

    I thought I had it licked with a new TDA2009A, but I guess not
  6. kip

    kip Guest

    Sounds like maybe the internal speakers are in the OFF
    postion in the Menu,s.
    Did you check the Menu,s ?
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