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Acer AL1916W - No Power

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    Acer AL1916W - No Power

    This monitor used to sometimes work when power button pressed which made it seem like a sticky power button to the original owner, now it's completely dead. No standby light no green power light.

    There's no voltage key at the secondary outputs but I do measure some voltages:
    5v, 5v. 2.7v the rest are 0v.

    There's 3.3v at the power button which does go low to 0v when it's pressed.

    Not sure if I'm to rule this a mainboard issue or not. Want to try manually turning the psu on to see if the rest of the voltages come up but don't know which pin it is. Any help would be appreciated
    Attached Files

    #2
    Re: Acer AL1916W - No Power

    Anyone?

    Comment


      #3
      Re: Acer AL1916W - No Power

      Try unplug cable from powerboard to mainboard, plug power cable in, see if backlights come on.

      Comment


        #4
        Re: Acer AL1916W - No Power

        Originally posted by nomoresonys View Post
        Try unplug cable from powerboard to mainboard, plug power cable in, see if backlights come on.
        No backlights when I try that. Also noticed with mainboard plugged in the power board makes a high pitched sound, but not when mainboard is unplugged

        Comment


          #5
          Re: Acer AL1916W - No Power

          Pull the boards and look for bad/cold solder joints, check the solder around the transformer/s and anything on a heatsink, CAREFUL what you touch capacitors can hold a charge for hours after power is removed. Warning is for those who might be looking on that might not be aware.
          Last edited by nomoresonys; 08-27-2019, 08:56 AM.

          Comment


            #6
            Re: Acer AL1916W - No Power

            Originally posted by nomoresonys View Post
            Pull the boards and look for bad/cold solder joints, check the solder around the transformer/s and anything on a heatsink, CAREFUL what you touch capacitors can hold a charge for hours after power is removed.
            I've already tried that and touched up a couple suspicious joints. Didn't change anything

            Comment


              #7
              Re: Acer AL1916W - No Power

              Can you pinpoint the screech? maybe use a hollow hose to your ear or sum such.

              Comment


                #8
                Re: Acer AL1916W - No Power

                The + 5volts on pins 1&2 is correct, pin3 is vbri and pin 4 is Ven, 5&6 are ground
                Check the voltage on JP1, I believe it should be around 14v, it supplies the inverter section.

                To turn on the power supply, disconnect the main board cable. and use a 1k restsor between pin1 (+5v) and pin4 (VEN). You may also need a 1k between pin1 and pin3 (VBRI)
                C809 (100µf/50v) could be bad/weak in the primary

                There are two voltage regulator ic's on the main board, U6 (3.3v) and U7 (1.8v) Check there output voltages, You can check the voltage on the tab.
                Last edited by R_J; 08-27-2019, 09:59 AM.

                Comment


                  #9
                  Re: Acer AL1916W - No Power

                  Try heating the capacitors of the powerboard with a hairdryer, see if the screech changes any.

                  Comment


                    #10
                    Re: Acer AL1916W - No Power

                    Originally posted by caphair View Post
                    No backlights when I try that. Also noticed with mainboard plugged in the power board makes a high pitched sound, but not when mainboard is unplugged
                    I have found shorts on the main board can cause the PS transformer to squeal. Check for shorts on the voltage rails of the main board and then try to narrow down to decoupling caps.

                    Comment


                      #11
                      Re: Acer AL1916W - No Power

                      Originally posted by R_J View Post
                      The + 5volts on pins 1&2 is correct, pin3 is vbri and pin 4 is Ven, 5&6 are ground
                      Check the voltage on JP1, I believe it should be around 14v, it supplies the inverter section.

                      To turn on the power supply, disconnect the main board cable. and use a 1k restsor between pin1 (+5v) and pin4 (VEN). You may also need a 1k between pin1 and pin3 (VBRI)
                      C809 (100µf/50v) could be bad/weak in the primary

                      There are two voltage regulator ic's on the main board, U6 (3.3v) and U7 (1.8v) Check there output voltages, You can check the voltage on the tab.
                      U6 and U7 output proper voltages.

                      Where's JP1? What's the 2.7v I measure from power board? Seems like an odd voltage but it's steady as well as the other 5v's

                      C809 seems to be a different brand of cap than the others I'll investigate it. Also wonder if that glue around it has become corrosive but it seems to be a silicone rather than the old type that would become an issue. Is that cap part of the switching ic?

                      Comment


                        #12
                        Re: Acer AL1916W - No Power

                        The 2.7V is probably the BL-ON (VEN).
                        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


                          #13
                          Re: Acer AL1916W - No Power

                          JP1 is near U802, or use D841 cathode. It is the supply voltage for the inverter section. That 2.7v is coming from the main board, it is the VBRI, brightness signal for the backlights.
                          C809 is likely ok if you have +5v and +14v. It is the VCC filter cap for the smps ic. If c809 failed you would not have the standby voltage.
                          Last edited by R_J; 08-27-2019, 06:53 PM.

                          Comment


                            #14
                            Re: Acer AL1916W - No Power

                            Originally posted by R_J View Post
                            JP1 is near U802, or use D841 cathode. It is the supply voltage for the inverter section. That 2.7v is coming from the main board, it is the VBRI, brightness signal for the backlights.
                            C809 is likely ok if you have +5v and +14v. It is the VCC filter cap for the smps ic. If c809 failed you would not have the standby voltage.
                            With the mainboard connected I get 20v on JP1. With it disconnected the voltage varies 8v-14v. Also with mainboard connected the transformer in the inverter section makes a squealing sound but no noise with mainboard disconnected.

                            If I jumper 5v to pin 4 to turn on the supply, what voltages should I be able to measure to determine if working properly? Should I have the backlights connected to see if they turn on?

                            Comment


                              #15
                              Re: Acer AL1916W - No Power

                              Mainboard Issue?

                              Comment


                                #16
                                Re: Acer AL1916W - No Power

                                Anyone?

                                Comment


                                  #17
                                  Re: Acer AL1916W - No Power

                                  Bump

                                  Comment


                                    #18
                                    Re: Acer AL1916W - No Power

                                    Originally posted by nomoresonys View Post
                                    Can you pinpoint the screech? maybe use a hollow hose to your ear or sum such.
                                    It's still present but changes tone when the power button is pressed or held

                                    Comment


                                      #19
                                      Re: Acer AL1916W - No Power

                                      It is better to use an oscilloscope or an esr meter to check for bad caps on the IP board, but next it probably need a reprogram of the eprom or the microcontroller on the interface board due ripple corruption of them.

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