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What is telephony? where does the VCC come from?

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    What is telephony? where does the VCC come from?

    I have a Magnum ME2012 Power inverter and out of the main logic board I have phone cable with a RJ45 female jack. in the cab of the vehicle I have a display panel with another female RJ45 jack. the phone cable connects these 2 guys together and I can set things like max amp draw, low voltage cut out etc.

    On the remote controller I have only 2vdc on the VCC legs of the op-amps and micro controller. I cant seem to find anyone who knows anything about power inverters or is willing to help fix this. I picture in the phone line that there is a twisted pair for communications and a VCC positive and a ground? it makes sense from an automotive design standpoint. I am also being told that telephony does not have a "heavy lifting VCC DC in the cable and that the analog voltage rides along the twisted pair com wires" im not sure if this is true or how that would even work.

    I can post photos if someone is willing to help me.

    Jason

    #2
    Re: What is telephony? where does the VCC come from?

    check the voltage at the connectors on both ends to see if your losing voltage in the connectors.

    Comment


      #3
      Re: What is telephony? where does the VCC come from?

      Upload good clear pictures so we can see what we are dealing with.
      Is this the one?
      https://cdn.badcaps-static.com/pdfs/...a65e6161a5.pdf
      Attached Files
      Last edited by budm; 12-18-2015, 11:05 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


        #4
        Re: What is telephony? where does the VCC come from?

        The manual states that the communication interface is RS485.

        This circuit might provide some insight into what you can expect:

        http://pinouts.ru/Converters/rs485_cable_pinout.shtml

        Comment


          #5
          Re: What is telephony? where does the VCC come from?

          Remote unit.
          Attached Files
          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


            #6
            Re: What is telephony? where does the VCC come from?

            Yes BudM that link is the one that I have and I am working on.

            The inverter box part is working and making the 110v modified square wave. I can put a 10-15 amp draw on it and it seems to work just fine. its just the remote that does not want to come alive.
            Attached Files

            Comment


              #7
              Re: What is telephony? where does the VCC come from?

              deleted
              Attached Files
              Last edited by fzabkar; 12-20-2015, 08:13 PM. Reason: deleted

              Comment


                #8
                Re: What is telephony? where does the VCC come from?

                Dammit!! No I am not!!! I had a problem with the original cable that came installed with this thing. It stopped working so I bought a new phone cable to replace it. It worked and lasted a few months. After 3 phone cables and all worked, I realized the female jack was corroded. I thought the corrosion was my problem. I pulled the unit from the vehicle and replaced the female jacks, now I am in this predicament where the new or old phone cords don't work.

                Comment


                  #9
                  Re: What is telephony? where does the VCC come from?

                  Recheck your work. Perhaps you've got a solder bridge short or a bad solder joint.

                  Comment


                    #10
                    Re: What is telephony? where does the VCC come from?

                    ' I thought the corrosion was my problem. I pulled the unit from the vehicle and replaced the female jacks,' So you replaced the FEMALE phone jack on the main unit or on the remote unit? Did you do the resistance test on all four pins between the main unit and the Remote unit? Correct phone wire per post 7?
                    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


                      #11
                      Re: What is telephony? where does the VCC come from?

                      The OP mentions an RJ45 jack, but that's 8-pin. The ME-ARC uses a 6P4C RJ11/RJ14 connector. Moreover, I didn't realise that phone cables had reverse pinouts at each end, so I had to check my own. Sorry about the mistake.

                      Comment


                        #12
                        Re: What is telephony? where does the VCC come from?

                        I seem to have 2 sets shorted, it appears to be by design, I can follow the traces. the other pins are free and clear of each other.

                        these female jacks have 6 pins

                        I have only replaced the 4 female jacks on the main unit and I have not replaced the female plug on the remote.
                        Attached Files

                        Comment


                          #13
                          Re: What is telephony? where does the VCC come from?

                          I would identify the RS485 transceiver ICs at each end. One or more of those 8-pin ICs should be likely suspects. Then examine the IC's datasheet. This will tell you its power and data pins. Then trace these pins to the respective jack(s).

                          Comment


                            #14
                            Re: What is telephony? where does the VCC come from?

                            I would find out which pin of the female phone jack is the VCC pin, GND pin the check out the resistance between the VCC supply pin of the main unit to see if you do have conection all the way to the remote unit VCC pin of the female phone jack, do the same for 3 other pins.
                            You should verify that one pin of the Remote female jack on the main unit has VCC (5V? 12V?), and one or more pins are GND. It only uses 4 wires.
                            Then you should at least find out if you do have good connection between the two unit first.
                            It is double sided board when you removed all those pins, the feed through between the top layer and the bottom layer may be damaged.
                            Last edited by budm; 12-20-2015, 11:23 PM.
                            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


                              #15
                              Re: What is telephony? where does the VCC come from?

                              Originally posted by scampo77 View Post
                              Dammit!! No I am not!!! I had a problem with the original cable that came installed with this thing. It stopped working so I bought a new phone cable to replace it. It worked and lasted a few months. After 3 phone cables and all worked, I realized the female jack was corroded. I thought the corrosion was my problem. I pulled the unit from the vehicle and replaced the female jacks, now I am in this predicament where the new or old phone cords don't work.
                              Did you check the phone cable that had work and then stop working? This is where I would start. If one of the lines opened up you could have a short that melts that cable line. I know on converters that they are not protected against such a thing happening even with all there fuses. A friend of mine had a RV converter and it was literally smoking and all the fuses were fine. I know this is different as it is an inverter. I just would not trust that it is protected. Also RJ11 connectors and lines on phone systems can carry 45VDC on hook and 110VAC for the ring. Twisted pairs have an impedance of 128 ohms. Used to get rid of AC Hum in old tube TVs.
                              Last edited by keeney123; 12-21-2015, 12:32 AM.

                              Comment


                                #16
                                Re: What is telephony? where does the VCC come from?

                                VDD Voltage Drain (MOSFET, N-Channel)
                                VSS Voltage Source (MOSFET, N-Channel)
                                VEE Voltage Emitter (BJT, NPN)
                                VCC Voltage Collector (BJT, NPN)
                                B+ B battery positive

                                Maybe? At least it's a guess? Just pulling this out of ... eh... nevermind.
                                Last edited by eccerr0r; 12-21-2015, 09:53 AM.

                                Comment


                                  #17
                                  Re: What is telephony? where does the VCC come from?

                                  C .25 vdc
                                  D 3 vdc

                                  A,B, Ground

                                  E.F, 0 vdc

                                  The connections are good between the remote and the logic board. I have 0 ohms straight across each lead

                                  terminals E and F don't seem to do anything and terminal D doesn't seem to be strong enough to light up the remote. I think this is possibly the problem??
                                  Attached Files

                                  Comment


                                    #18
                                    Re: What is telephony? where does the VCC come from?

                                    Here are some more measurements and some more photos.

                                    there is no loss between the output of the logic board and the input of the remote.

                                    I have negative voltage at one pin, I do not know what this means.

                                    the IC in the photo of the logic board has 483ECN and 0448 on it and also possibly SIPEX ?

                                    the IC above it are LM393 and the one below it are LM358A.

                                    on the photo labeled "back of logic" there is an image of terminal B -1.1v and its very close to solder dot, I don't know if these are supposed to be connected or not. I have enclosed a closer photo, the "dot" has 5v.

                                    please don't forget, this stopped working, Then I pulled it and replaced the female connectors and now its still not working (or at least the same as it was before)
                                    Attached Files

                                    Comment


                                      #19
                                      Re: What is telephony? where does the VCC come from?

                                      So I am confused as one place you list A,B as ground and another place you are listing C as ground. This is a very simple circuit. Do you measure 5Volts DC when you measure from pin 5 to pin 8 on the 483ECN on the remote board? If you look at your picture of the remote the microchip seems like lines are shorted in the middle of the pin on the bottom part of the chip. I can not make out where pin 1 is or the number of the chip.
                                      Last edited by keeney123; 12-27-2015, 06:44 PM.

                                      Comment


                                        #20
                                        Re: What is telephony? where does the VCC come from?

                                        Please ignore post #17, the logic board slides into the inverter like a video card on a PC. I was trying to probe around a corner and I was measuring the wrong port. I have since pulled all of the tin heat shields apart. The previous post (#18) is actual measurements. Moving forward I will do my best to keep the letters and colors the same.

                                        The IC on the remote pin has only 2V at pin 8 with my ground lead on pin5

                                        I have enclosed photos of the micro controller on the remote board. before I started this thread, I found the VCC pins on the controller and they are all at 2v
                                        Attached Files

                                        Comment

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