Need Help with this Circuit Please

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  • SteveNielsen
    Retired Tech
    • Jun 2012
    • 2327
    • USA

    #21
    Re: Need Help with this Circuit Please

    Just out of curiosity can you show pictures of the damage? Traces on audio boards are ofter repairable. They are not multi-layer computer boards with tiny traces.

    Comment

    • Khron
      Badcaps Legend
      • Sep 2006
      • 1350
      • Finland

      #22
      Re: Need Help with this Circuit Please

      Well, despite that, even IF you had to retrofit a separate power amp, are you really sure you wanna take quite SUCH a "cheap" route, amp-wise?

      For what it's worth, for about 40$ shipped it seems, you can get a pair of P3A pcb's - http://sound.westhost.com/pcb/pp3a.htm

      You could potentially re-use (at least) the good silicon from the stock amp board, perhaps also some of the passives, so even the component cost wouldn't be all that much extra But that's just my pair of pennies...
      Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

      Comment

      • SteveNielsen
        Retired Tech
        • Jun 2012
        • 2327
        • USA

        #23
        Re: Need Help with this Circuit Please

        Indeed, there's more than one way to skin a cat.

        Comment

        • stj
          Great Sage 齊天大聖
          • Dec 2009
          • 30937
          • Albion

          #24
          Re: Need Help with this Circuit Please

          oldskool design.
          http://www.ebay.com/itm/161852896480

          Comment

          • tfs2015
            Senior Member
            • Feb 2015
            • 135
            • USA

            #25
            Re: Need Help with this Circuit Please

            stand By for picture
            Computer and Small electronics troubleshooting and repair

            Comment

            • keeney123
              Lauren
              • Sep 2014
              • 2536
              • United States

              #26
              Re: Need Help with this Circuit Please

              Some amps in the 60's just had a board with no circuitry. The board was used just to mount the components and wires were soldered point to point.

              Comment

              • tfs2015
                Senior Member
                • Feb 2015
                • 135
                • USA

                #27
                Re: Need Help with this Circuit Please

                Looks like I did damage on top of damage when I removed the burnt transistors. Tell me can this be fixed or am I looking at a total rebuild of the board and or circuit.

                Thanks
                Tom
                Attached Files
                Computer and Small electronics troubleshooting and repair

                Comment

                • stj
                  Great Sage 齊天大聖
                  • Dec 2009
                  • 30937
                  • Albion

                  #28
                  Re: Need Help with this Circuit Please

                  tracks look o.k. - just loads of sludgy solder all over them that needs cleaning off.
                  then clean the flux off with IPA and take fresh foto's

                  Comment

                  • SteveNielsen
                    Retired Tech
                    • Jun 2012
                    • 2327
                    • USA

                    #29
                    Re: Need Help with this Circuit Please

                    Yeah, get rid of the blobs of solder and clean the board. Go easy on the pads with the heat so they don't pull up but I don't see damage to traces either, if there are they can be repaired on this board.

                    Comment

                    • tfs2015
                      Senior Member
                      • Feb 2015
                      • 135
                      • USA

                      #30
                      Re: Need Help with this Circuit Please

                      The pads are the parts that I am concerned about because some of them pulled up when I was desoldering the bad power transistors.
                      Computer and Small electronics troubleshooting and repair

                      Comment

                      • keeney123
                        Lauren
                        • Sep 2014
                        • 2536
                        • United States

                        #31
                        Re: Need Help with this Circuit Please

                        Originally posted by tfs2015
                        The pads are the parts that I am concerned about because some of them pulled up when I was desoldering the bad power transistors.
                        I would use solder wick to clean the solder up. Just do not let iron stay to long on the braid. You would want to put a little flux on the solder joints and make sure the tip on the solder iron is tinned, place the braid on the solder that you want to pull up, then put the iron on the braid. The heat will transfer down through the braid heating up the solder. The solder will suck up into the braid as the braid becomes full you will need to feed unused braid into the solder. This should happen in one quick motion. Just make sure you have enough braid out so when you fed it in you do not burn your fingers. If it seems like it is taking to long then you will have to let the solder cool down again and try again. You do this to prevent burning of the board or pad.

                        Comment

                        • tfs2015
                          Senior Member
                          • Feb 2015
                          • 135
                          • USA

                          #32
                          Re: Need Help with this Circuit Please

                          If I am unable to repair this circuit board to get the amp working, is there an amp circuit that I can use to put onto a new circuit board maybe one that is not as complicated as this one?
                          Computer and Small electronics troubleshooting and repair

                          Comment

                          • tfs2015
                            Senior Member
                            • Feb 2015
                            • 135
                            • USA

                            #33
                            Re: Need Help with this Circuit Please

                            Some of the pads have broken off of the traces
                            Computer and Small electronics troubleshooting and repair

                            Comment

                            • stj
                              Great Sage 齊天大聖
                              • Dec 2009
                              • 30937
                              • Albion

                              #34
                              Re: Need Help with this Circuit Please

                              fine, use jump wires - those transistors are mounted on a heatsink.

                              if you give up, look at the ebay link i posted in post#24

                              Comment

                              • tfs2015
                                Senior Member
                                • Feb 2015
                                • 135
                                • USA

                                #35
                                Re: Need Help with this Circuit Please

                                can't use that eBay item says that it uses AC power and the only power I have available is DC Power. I appreciate the information.
                                Computer and Small electronics troubleshooting and repair

                                Comment

                                • tfs2015
                                  Senior Member
                                  • Feb 2015
                                  • 135
                                  • USA

                                  #36
                                  Re: Need Help with this Circuit Please

                                  What size wire would I need to use as the jumper Wire? I have 18 ga. solid right now.
                                  Computer and Small electronics troubleshooting and repair

                                  Comment

                                  • SteveNielsen
                                    Retired Tech
                                    • Jun 2012
                                    • 2327
                                    • USA

                                    #37
                                    Re: Need Help with this Circuit Please

                                    18 ga is too big. I use clipped off leads from parts like small resistors or caps for that.

                                    Comment

                                    • budm
                                      Badcaps Legend
                                      • Feb 2010
                                      • 40746
                                      • USA

                                      #38
                                      Re: Need Help with this Circuit Please

                                      Originally posted by tfs2015
                                      can't use that eBay item says that it uses AC power and the only power I have available is DC Power. I appreciate the information.
                                      You just feed the DCV directly to the two main filter caps. Your amp has SMPS power supply or linear power supply?
                                      Never stop learning
                                      Basic LCD TV and Monitor troubleshooting guides.
                                      http://www.badcaps.net/forum/showthr...956#post305956

                                      Voltage Regulator (LDO) testing:
                                      http://www.badcaps.net/forum/showthr...999#post300999

                                      Inverter testing using old CFL:
                                      http://www.badcaps.net/forum/showthr...er+testing+cfl

                                      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                      http://s807.photobucket.com/user/budm/library/

                                      TV Factory reset codes listing:
                                      http://www.badcaps.net/forum/showthread.php?t=24809

                                      Comment

                                      • stj
                                        Great Sage 齊天大聖
                                        • Dec 2009
                                        • 30937
                                        • Albion

                                        #39
                                        Re: Need Help with this Circuit Please

                                        i think ebay add is wrong, i dont see any rectifier diodes in the foto.
                                        even if it had some you could bypass them.

                                        i think the chinese just meant use a split suppy.

                                        Comment

                                        • budm
                                          Badcaps Legend
                                          • Feb 2010
                                          • 40746
                                          • USA

                                          #40
                                          Re: Need Help with this Circuit Please

                                          The bridge is attached to the heatsink.
                                          Attached Files
                                          Last edited by budm; 11-19-2015, 11:44 AM.
                                          Never stop learning
                                          Basic LCD TV and Monitor troubleshooting guides.
                                          http://www.badcaps.net/forum/showthr...956#post305956

                                          Voltage Regulator (LDO) testing:
                                          http://www.badcaps.net/forum/showthr...999#post300999

                                          Inverter testing using old CFL:
                                          http://www.badcaps.net/forum/showthr...er+testing+cfl

                                          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                          http://s807.photobucket.com/user/budm/library/

                                          TV Factory reset codes listing:
                                          http://www.badcaps.net/forum/showthread.php?t=24809

                                          Comment

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