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Hilariously cheap car audio amp (Cougar C-300.4)

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    #21
    Re: Hilariously cheap car audio amp (Cougar C-300.4)

    Pictures!

    I just noticed instead of part #s they actually use device names, I suppose it makes it easier to reverse engineer but WHY? Especially in China!
    Attached Files
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    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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      #22
      Re: Hilariously cheap car audio amp (Cougar C-300.4)

      I've seen that style of PCB in a china special class AB discrete amp i have at home. Component values instead of part IDs... check. Tons of jumper links... check. Font... check. No idea who actually makes them tho, but it could be those guys: http://windy56wu.en.ec21.com/

      What's up with that SMPS in it? The 7377 is designed to run straight off the car battery.
      Originally posted by PeteS in CA
      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
      A working TV? How boring!

      Comment

        #23
        Re: Hilariously cheap car audio amp (Cougar C-300.4)

        Originally posted by Th3_uN1Qu3 View Post
        What's up with that SMPS in it? The 7377 is designed to run straight off the car battery.
        Not an SMPS. Just an input filter. At least, that's as far as I can tell; the output peaks at 13V anyway.
        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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          #24
          Re: Hilariously cheap car audio amp (Cougar C-300.4)

          What kind of input filter is that with two mosfets and a diode bolted to a heatsink, with a TL494 driving them?
          Originally posted by PeteS in CA
          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
          A working TV? How boring!

          Comment

            #25
            Re: Hilariously cheap car audio amp (Cougar C-300.4)

            Originally posted by Th3_uN1Qu3 View Post
            What kind of input filter is that with two mosfets and a diode bolted to a heatsink, with a TL494 driving them?
            Good point. Just noticed the TL494. But, it doesn't work - maybe as a result of being dropped or maybe by poor design.
            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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              #26
              Re: Hilariously cheap car audio amp (Cougar C-300.4)

              You should check why it won't work - maybe with that operational the amp will actually deliver full output at 12v in.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

              Comment

                #27
                Re: Hilariously cheap car audio amp (Cougar C-300.4)

                Originally posted by Th3_uN1Qu3 View Post
                You should check why it won't work - maybe with that operational the amp will actually deliver full output at 12v in.
                Well, it would potentially give 65W (PEAK) per channel if working (18V, assume 1V rail limit, 16V^2/4 = 65). But the 7377 is 18V maximum; so the boosting can't be that significant; and the amp might current limit near the edges of the rails. Maybe it's a boost converter but what boost converter uses two FETs?
                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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                  #28
                  Re: Hilariously cheap car audio amp (Cougar C-300.4)

                  Originally posted by tom66 View Post
                  Well, it would potentially give 65W (PEAK) per channel if working (18V, assume 1V rail limit, 16V^2/4 = 65). But the 7377 is 18V maximum; so the boosting can't be that significant; and the amp might current limit near the edges of the rails. Maybe it's a boost converter but what boost converter uses two FETs?
                  Could be a push-pull. But since it's still receiving power with the SMPS dead, it's a giveaway that it's a boost. Troubleshoot it and see.
                  Originally posted by PeteS in CA
                  Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                  A working TV? How boring!

                  Comment

                    #29
                    Re: Hilariously cheap car audio amp (Cougar C-300.4)

                    Originally posted by Th3_uN1Qu3 View Post
                    Could be a push-pull. But since it's still receiving power with the SMPS dead, it's a giveaway that it's a boost. Troubleshoot it and see.
                    Maybe it's an odd form of flyback or forward based around a toroid given it's got two separate windings (at least it appears so.) Will ask my manager if he still wants it as he's relegated it to the crap pile. Although, I'm not sure what I would do with it if fixed as I don't own a car and have no need for such an amplifier -- always found them annoying personally. I can at least run it off my bench PSU with an analog meter, as the current bench supply is limited by the slow digital display, can't see if it's drawing a lot of current in bass peaks.
                    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                    Comment

                      #30
                      Re: Hilariously cheap car audio amp (Cougar C-300.4)

                      Originally posted by tom66 View Post
                      Will ask my manager if he still wants it as he's relegated it to the crap pile. Although, I'm not sure what I would do with it if fixed as I don't own a car and have no need for such an amplifier
                      Sell it?
                      Originally posted by PeteS in CA
                      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                      A working TV? How boring!

                      Comment

                        #31
                        Re: Hilariously cheap car audio amp (Cougar C-300.4)

                        Originally posted by Th3_uN1Qu3 View Post
                        Sell it?
                        I wouldn't want anyone to have the misfortune of this amplifier personally. Even fixed, if it is even broken, it's a pile of crap.
                        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                        Comment

                          #32
                          Re: Hilariously cheap car audio amp (Cougar C-300.4)

                          Just sell it and forget about personal feelings. If you do a good enough job of fixing it, chances are it's never going to come back.
                          Originally posted by PeteS in CA
                          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                          A working TV? How boring!

                          Comment

                            #33
                            Re: Hilariously cheap car audio amp (Cougar C-300.4)

                            Still have no idea why the toroid has two windings. Reminds me too much of some kind of toroid transformer design I've seen in cheap LCD TVs. Not sure why they used that over an E-core or similar but...
                            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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                              #34
                              Re: Hilariously cheap car audio amp (Cougar C-300.4)

                              Originally posted by tom66 View Post
                              Not sure why they used that over an E-core or similar but...
                              Low profile. Also, in a car environment, you need no isolation between the primary and secondary, so you can wind multifilar on a toroid no problem.
                              Originally posted by PeteS in CA
                              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                              A working TV? How boring!

                              Comment

                                #35
                                Re: Hilariously cheap car audio amp (Cougar C-300.4)

                                Originally posted by Th3_uN1Qu3 View Post
                                Low profile. Also, in a car environment, you need no isolation between the primary and secondary, so you can wind multifilar on a toroid no problem.
                                It is about an inch thick so fairly low profile; so I guess it must be some form of non-isolated transformer based converter. I will try and trace the SMPS part out if I get some time.
                                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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                                  #36
                                  Re: Hilariously cheap car audio amp (Cougar C-300.4)

                                  Originally posted by tom66 View Post
                                  I wouldn't want anyone to have the misfortune of this amplifier personally. Even fixed, if it is even broken, it's a pile of crap.
                                  You could have some fun with it, blow it up?
                                  Muh-soggy-knee

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                                    #37
                                    Re: Hilariously cheap car audio amp (Cougar C-300.4)

                                    thats a standard smps used in most mobile amps.gives a + and - supply.
                                    Originally posted by tom66 View Post
                                    Not an SMPS. Just an input filter. At least, that's as far as I can tell; the output peaks at 13V anyway.

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                                      #38
                                      Re: Hilariously cheap car audio amp (Cougar C-300.4)

                                      Originally posted by kc8adu View Post
                                      thats a standard smps used in most mobile amps.gives a + and - supply.
                                      This thing wouldn't be using split supply though; the BTL drive outputs measure 6V idle.
                                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                      Comment

                                        #39
                                        Re: Hilariously cheap car audio amp (Cougar C-300.4)

                                        The coil has about four windings. Not sure what all of them are for as only one provides V+ for the amps. Maybe others are just mechanical support or auxillary windings for other stuff.

                                        OK, so some diagnosis:
                                        - Vcc to TDA7377's is only 12.6V with 13.8V in; so the boost converter isn't working
                                        - Vcc to TL494 is only 5.3V; minimum is 7V for guaranteed operation. Something is not allowing it to power up as it has a limited supply, but not the full supply it needs.

                                        The ST 7808 regulator is fake as the printing and font is totally different to all of my ST voltage regulators.

                                        Maybe the TL494 is only powered up on heavy bass? That would make it a rather interesting Class-G design; or if it varies the supplies, a Class-H.
                                        Last edited by tom66; 08-21-2012, 03:24 AM.
                                        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                        Comment

                                          #40
                                          Re: Hilariously cheap car audio amp (Cougar C-300.4)

                                          Originally posted by tom66 View Post
                                          Maybe the TL494 is only powered up on heavy bass? That would make it a rather interesting Class-G design; or if it varies the supplies, a Class-H.
                                          Don't think so. You said you have a scope - check the outputs of the 494, see if it's trying to do anything. This may be an unregulated converter - hence the Vcc of the 494 isn't too important, since Vref isn't needed.
                                          Originally posted by PeteS in CA
                                          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                          A working TV? How boring!

                                          Comment

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