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Amplifier wiring problem

Discussion in 'General Electronics Discussion' started by Pexy, Apr 13, 2016.

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  1. Pexy

    Pexy

    142
    3
    Feb 21, 2016
    Greetings. My brother gave me a speaker amplifier circuit to play with. But. In order to see if it works and how it works I need to power it up. It has a 5 pin connector but I don't know what some of the markings mean. Would someone please write me the meaning of markings? Here's two pictures of the amp and markings.
    Thanks.
    12992731_1269800549714623_1357076616_n.jpg
    13014833_1269800576381287_481933710_n.jpg
     
  2. Bluejets

    Bluejets

    5,029
    1,050
    Oct 5, 2014
    Can you show the rest of it. i.e. where the ribbon cable goes.
    As it is ...
    LIN = Left Channel In
    RIN = Right channel in
    V+ = supply positive (but unknown what voltage level)
    V- = Supply negative ( ditto)
    Ground = Common for the supply and the 2 signals.
     
  3. Pexy

    Pexy

    142
    3
    Feb 21, 2016
    Thanks but I don't have the rest of it
     
  4. Pexy

    Pexy

    142
    3
    Feb 21, 2016
    I forgot he gave me the transformer, Lin and Rin by the looks of it and another small circuit. 13020605_1269819859712692_1360477547_n.jpg
    The transformer has a 2 pin connector(probobly the V+ and V-)
    And the Rin and Lin cable has a 3 pin connector (porbobly the Lin, Rin and Ground is labeld there) the amp has a 5pin connector so im missing the middle pice of the amp system.
     
    Last edited: Apr 13, 2016
  5. ramussons

    ramussons

    385
    73
    Jun 10, 2014
    There seems to be another module missing ..... the power supply module that has to come between the Transformer and the Amp.
     
  6. Anon_LG

    Anon_LG

    453
    117
    Jun 24, 2014
    This means that your afformentioned battery pack from a previous thread will probably need to have conversion circuitry to create negative and positive rails respective to common. The problem is, what voltage?

    I may see a voltage regulator. Pexy, the black component with the metal back, next to the GND input, labeled 35V, can you tell us the numbers and letters on it please. It probably is a regulator, but knowing the part code will tell us the voltage range to input.

    Thanks,
     
  7. Pexy

    Pexy

    142
    3
    Feb 21, 2016
    Sry but this is unrelated to the other speakers anf theme that I previously mentioned. Yes there is a voltage regulator(KA7812 G43)
     
  8. Anon_LG

    Anon_LG

    453
    117
    Jun 24, 2014
    OK, excuse my assumption.

    You have a twelve volt positive regulator, here is the datasheet pertaining. There is a dropout of 2 volts and an absolute maximum voltage of 35 volts. This means your positive input should be anywhere from 15 to 25 volts to ensure stable operation. (It could be 14 to 35 in, but you risk instability or damage respectively). Could you provide an image showing the connections from the voltage regulator to the inputs? This will enable me to make a more certain evaluation.

    Is there another voltage regulator on the board?

    Thanks,
     
  9. Bluejets

    Bluejets

    5,029
    1,050
    Oct 5, 2014
    Without the other board you are essentially up a creek without a paddle.
    If the extra parts you have shown were indeed from the original, then the transformer which has a split output. i.e. 2 x blue and black cable would have gone to some type of rectifier(x1) regulator(x2) to become the V+, V- , and common.
    Other bits, who knows.
    Bits for the junk bin in total I'd say.
     
  10. Anon_LG

    Anon_LG

    453
    117
    Jun 24, 2014
    I would say it is always worth a try, modifying an existing product is just as exciting as making your own. And what is the point in throwing something away unless it is useless? Say they put it in the bin, the product will be destroyed in a landfill site and nobody will gain anything. Alternatively, Pexy can experiment, if they fry it then it can be thrown away, (but please recycle it responsibly). If however he gets it working, they now have an item of value, have gained experience and there will be one less item in landfill.

    @Pexy is your bench supply a dual/split supply? If the voltages are not identifiable, the only method is to slowly ramp up the voltage by a small amount each time. I found and got working two EL inverters using this method and no damage was dealt. All you have to do is keep turning the voltage up until the speakers reliably stay on. Place your power supplies in a configuration the same as in the image below (Courtesy of Google images) The rail marked zero goes to GND, the positive to V+ and the negative to V-. Make sure that your positive and negative supplies are the same voltage. Increase both by possibly half a volt each time and test.
    Split Rail Supply.jpg
     
  11. Bluejets

    Bluejets

    5,029
    1,050
    Oct 5, 2014
    Appears the whole pre-amp section including controls are missing and as such the power supply would be about a 1 on a scale of 1 to 50.
     
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