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Schematic for RCA RS2640

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  • Schematic for RCA RS2640

    Does anyone happen to have a schematic for this all in one stereo ?? Was cutting out once it warmed up , now it just buzzes no audio .
    If you don't know where your going any road'll take you there : George Harrison

  • #2
    Originally posted by shortcircuit View Post
    it just buzzes no audio .
    Classic symptom of a failed main filter capacitor. I don't have a schematic. It shouldn't take too much head-scratching to find that cap and clip another similarly rated one in its place, see if your prize starts working again.
    This isn't the future I signed up for.

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    • #3
      Originally posted by Leo_Gnardo View Post
      Classic symptom of a failed main filter capacitor. I don't have a schematic. It shouldn't take too much head-scratching to find that cap and clip another similarly rated one in its place, see if your prize starts working again.
      Thank You , actually got one of them to spill it's guts , all my replacements are to low voltage ,will be on my next order.
      If you don't know where your going any road'll take you there : George Harrison

      Comment


      • #4
        Originally posted by shortcircuit View Post
        Thank You , actually got one of them to spill it's guts , all my replacements are to low voltage ,will be on my next order.
        Replaced both main filter caps plus one other, still just a buzz , you can hear the volume click up on the speakers, no audio output from any of the functions cd,tape etc or headphones. any suggestions ?? , start tracing
        Click image for larger version

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        Last edited by shortcircuit; 03-28-2018, 06:00 PM.
        If you don't know where your going any road'll take you there : George Harrison

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        • #5
          Schematic is here:

          https://elektrotanya.com/rca_rs2640.pdf/download.html

          I would start by checking all power supply voltages.
          "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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          • #6
            Originally posted by The Dude View Post
            Schematic is here:

            https://elektrotanya.com/rca_rs2640.pdf/download.html

            I would start by checking all power supply voltages.
            Thank You very much , you are The Dude , appreciate your excellent support
            If you don't know where your going any road'll take you there : George Harrison

            Comment


            • #7
              Originally posted by The Dude View Post
              Schematic is here:

              https://elektrotanya.com/rca_rs2640.pdf/download.html

              I would start by checking all power supply voltages.
              Click image for larger version

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              D821= -31.47vdc
              D509-D512 =8.35vdc
              D505-D508 = 40.7vdc / -40.7vdc
              above and below 10% , bad transformer ??
              Last edited by shortcircuit; 03-30-2018, 02:31 PM. Reason: +
              If you don't know where your going any road'll take you there : George Harrison

              Comment


              • #8
                Originally posted by The Dude View Post
                Schematic is here:

                https://elektrotanya.com/rca_rs2640.pdf/download.html

                I would start by checking all power supply voltages.
                rca-2-.jpeg
                D821= -31.47vdc
                D509-D512 =8.35vdc
                D505-D508 = 40.7vdc / -40.7vdc
                above and below 10% , bad transformer ?? not blowing fuses, I'm thinking I need to get voltages to IC501 the audio amp I don't have any
                If you don't know where your going any road'll take you there : George Harrison

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                • #9
                  My apologies, I haven't gone through your measurements. A bit slammed at work today. If you don't have voltage to your audio amp, look at that rectifier circuit consisting of D505-D508. That's where supply comes from. Check the fuses F503 & F504. If one or both is open, it's likely one of your audio amps shorted. Check the audio amps supply pins to ground and to each other and make sure there are no shorts. If there are, you will just blow the fuses again. If those fuses are good, measure the AC voltage at N801A and make sure there is AC supplied to the rectifier circuit.
                  "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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                  • #10
                    Originally posted by The Dude View Post
                    My apologies, I haven't gone through your measurements. A bit slammed at work today. If you don't have voltage to your audio amp, look at that rectifier circuit consisting of D505-D508. That's where supply comes from. Check the fuses F503 & F504. If one or both is open, it's likely one of your audio amps shorted. Check the audio amps supply pins to ground and to each other and make sure there are no shorts. If there are, you will just blow the fuses again. If those fuses are good, measure the AC voltage at N801A and make sure there is AC supplied to the rectifier circuit.
                    fuses are good, have 29.25vac at N801a , have 40.7vdc & -40.7vdc from D505-D508 , thanks for the reply , no apologies necessary ,appreciate all you do and have done
                    ?? even if the amp was shorted wouldn't I have voltage to the pins 2&15 that should have 29.8v??
                    Last edited by shortcircuit; 03-30-2018, 10:24 PM. Reason: +
                    If you don't know where your going any road'll take you there : George Harrison

                    Comment


                    • #11
                      So you have DC out of the rectifier, but not at the IC suppy pins? If that's the case, you must have connection problems- cold solder, burnt trace, etc. Check continuity from your rectifier supply to the IC supply pins and verify that the connection is good.
                      "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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                      • #12
                        The +/- 40V should be showing up at pins 7 and 8 of the amp IC's, they are not there? It should be a straight run from the rectifiers, no burnt traces?
                        You said 8.35V at D510? What are voltages at pins 1&3 of IC503?
                        Originally posted by Enzo
                        I have a sign in my shop that says, "Never think up reasons not to check something."


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                        • #13
                          As a side note, I wouldn´t worry about finding +/-41V rails instead of +/-31.

                          TDA7293 are happy with both, 2 possibilities to explain the difference:
                          1) a plain old typo. Happens in the best families. The writer might have wanted to say "31V **AC** ... which will give you about 41V DC rails.
                          2) factory variation.
                          Maybe original version used 31V rails, then they improved it and offered the higher ones, which increase power out.

                          In any case, well within Power Amp ICs, so ...... no big deal.
                          Juan Manuel Fahey

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                          • #14
                            Originally posted by g1 View Post
                            The +/- 40V should be showing up at pins 7 and 8 of the amp IC's, they are not there? It should be a straight run from the rectifiers, no burnt traces?
                            You said 8.35V at D510? What are voltages at pins 1&3 of IC503?
                            Thank You g1
                            Have +/-40vdc at pins 7 & 8 , I owe The Dude an apology on that , voltage at IC503 pin1 18.65vdc , pin3 11.76vdc ,
                            IC501 pins 1,3,4,5,9,10,11,12 =0vdc pin 2=-1vdc , pin6 =13.35vdc (and starts dropping if you stay on it) 7&8 = 41/-41 vdc , pin13= 41vdc,pin 14= -1vdc , pin 15= -41vdc
                            my mistake was was going off the voltage chart on pg7-1,which is no where close to any of these
                            Last edited by shortcircuit; 03-31-2018, 01:26 PM. Reason: +
                            If you don't know where your going any road'll take you there : George Harrison

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                            • #15
                              Originally posted by J M Fahey View Post
                              As a side note, I wouldn´t worry about finding +/-41V rails instead of +/-31.

                              TDA7293 are happy with both, 2 possibilities to explain the difference:
                              1) a plain old typo. Happens in the best families. The writer might have wanted to say "31V **AC** ... which will give you about 41V DC rails.
                              2) factory variation.
                              Maybe original version used 31V rails, then they improved it and offered the higher ones, which increase power out.

                              In any case, well within Power Amp ICs, so ...... no big deal.
                              Thanks for the intel , appreciate it
                              If you don't know where your going any road'll take you there : George Harrison

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