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Soundlab G097F advice please.

Discussion in 'Electronic Repair' started by [email protected], May 10, 2007.

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  1. My neighbour has a Soudlab G097F amplifier that no longer functions.

    The symptoms are that everything seems to power up ok but the "protect"
    indicator lamp remains lit resulting in no output, whereas normaly it
    would only light up for a couple of seconds at power on before hearing a
    click and extinguishing, then fuction as normal.

    Could anyone suggest where I might start fault finding?

    Thanks.
     
  2. Arfa Daily

    Arfa Daily Guest

    First two places to look are for an external short across the output - ie a
    faulty speaker or wiring whisker, or someone having driven a nail through
    the speaker wire, and then look inside for an open fuse. If either supply
    rail is missing, it will stay in protect. However, any sign of a fuse being
    blown violently - blackened glass or metal beads - would indicate more
    serious trouble in the output stages. No signs of distress at all, could
    indicate a problem with the fault detect / relay drive circuit itself, or
    even possibly something as simple as a bad joint. What is your level of
    experience at working on this type of equipment, and what test equipment do
    you have ?

    Arfa
     
  3. Arfa Daily said...
    Thanks for your reply Arfa.

    I am an electrician by trade, but I have a basic knowledge of
    electronics although I only have a half decent multi-meter to hand.

    The fault persists with the speakers disconnected which themselves show
    no evidence of shorting,both the two glass fuses on the circuit board
    are fine and ther is no visual signs of overheating that I can see.

    The cooling fan comes on immediately at power on, but my neighbour
    insists this has been so since purchase.

    One thing I have found, is the sensor on the heat-sink is closed circuit
    in the amp's present state (cold) - should this be the case?

    (Sensor at bottom left corner of image 5 at
    http://picasaweb.google.co.uk/fayd2gray/G097F)
     
  4. One thing I have found, is the sensor on the heat-sink is closed circuit
    NOTE: disconnected from board when tested.
     
  5. Arfa Daily

    Arfa Daily Guest

    I would say that the thermoswitch reading closed, is correct. There are both
    open and closed types, but closed types in this application are by far the
    most common. I have looked at the images, and C210 leapt out at me (
    heatsink away from you, left side of board, just in front of centre
    connector ). This cap looked as if it had a domed top. I have looked at this
    from all the angles that I can, with the photos zoomed up, and it definitely
    looks as though it is. If it is domed, then that would be the very next
    thing that I would try with a replacement. I don't know how much actual
    electronics knowledge that you have, but faulty electrolytic caps are very
    very common, and a domed top is usually a red-flag giveaway. If it is, and
    you decide to have a go and replace it, note that these caps are polarised,
    so must be fitted the correct way round ( sorry if I'm treating you too dumb
    here ). The board may be marked with a "+" symbol, but more likely from what
    I can see, a bar at the "-" terminal. This corresponds to a stripe, usually
    marked "-" on the cap body itself.

    Arfa
     
  6. Arfa Daily

    Arfa Daily Guest

    Where yoo gon?

    Did you get any success with it ?

    Arfa
     
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