HiSense 55HtB power supply bench test: weird voltages

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  • MrCreosote
    Member
    • Dec 2005
    • 31
    #1

    HiSense 55HtB power supply bench test: weird voltages

    There was a power surge at home from "direct" (no sound delay !!!) lightning strike. Popped a 15 amp breaker for ceiling lights (old knob and tube wiring - perfect antenna?) "Fried" garage door opener buttons and remote, KVM switch, Magic Jack, and a ceiling fan motor.

    And my 55" 6 year old Hisense Black Friday Walmart TV.

    There is no Red standby LED.

    I was wondering how to "jumper" the board on to test voltages thinking the STB pin would be one of the pins.

    However, I decided to measure voltages at all 10 pins just so see there was something there to power the standby switch. What I found was something I cannot explain: Voltages with no power connection to board. Now I was working under 4 compact fluorescent light bulbs but that is a reach.

    Maybe this is telling me the board is fried?

    I have the board pinouts and the voltages are (line cord unplugged) / (line cord plugged to outlet) which is beyond my pay grade. Tried 2 different multi meters.

    1 gnd
    2 gnd
    3 pwm -0.2v / -2v
    4 sw
    5 12v
    6 12v
    7 stb
    8 gnd
    9 18v 22v / 24v
    10 18v 22v / 24v
    Tags: None
    • MrCreosote
      Member
      • Dec 2005
      • 31
      #2
      Re: HiSense 55HtB power supply bench test: weird voltages

      OK found the following definition of the unrecognized pinouts. Also appears this board does not have a 5v standby. Here is a copy from another thread:

      Where is the 5V pin on this board? I do not see one.
      https://www.badcaps.net/forum/attachm...3&d=1472170236

      STB = PS-ON
      SW = BL-ON
      PWM = PWM dimming

      RE: Measured Voltages: the 24v is troublesome: much higher than the 18v spec'd.

      Also, the voltage measured with no power to board could be caps still charged up? But I repeated measurements w/ and w/o power and the values alternated between 22 and 24. If charged caps, I would expect 24 and 24 or the 22 would would change with time while discharging. Could get a VOM to put a little load on it.

        Comment

        • lotas
          Badcaps Legend
          • Jan 2016
          • 4540
          • Russia
          #3
          Re: HiSense 55HtB power supply bench test: weird voltages

          STB is the standby power supply (voltage DC5V).

          STB can be 3 - 6v DC
          Last edited by lotas; 08-13-2021, 11:14 AM.

            Comment

            • lotas
              Badcaps Legend
              • Jan 2016
              • 4540
              • Russia
              #4
              Re: HiSense 55HtB power supply bench test: weird voltages

              PWM - backlight level
              SW - switching on the main power supply 12V and 24v.
              no load and will jump power to 24v.

                Comment

                • MrCreosote
                  Member
                  • Dec 2005
                  • 31
                  #5
                  Re: HiSense 55HtB power supply bench test: weird voltages

                  Both STB and SW are 0v.

                  So I've go NO standby power supply and the 18v pins are running 24v.

                  RIP power supply board.

                    Comment

                    • Th3_uN1Qu3
                      Believe in
                      • Jul 2010
                      • 6031
                      • Romania
                      #6
                      Re: HiSense 55HtB power supply bench test: weird voltages

                      I would not worry about 18V being 24V for now. The standby section should be fixable, it should be nothing more than replacing the switching IC, startup resistor and associated capacitors and maybe the optoisolator.
                      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

                        • R_J
                          Badcaps Legend
                          • Jun 2012
                          • 9535
                          • Canada
                          #7
                          Re: HiSense 55HtB power supply bench test: weird voltages

                          Originally posted by MrCreosote
                          Both STB and SW are 0v.

                          So I've go NO standby power supply and the 18v pins are running 24v.

                          RIP power supply board.
                          I answered this in your other thread, The power supply board is working fine, it does NOT supply a separate standby 5 volts
                          STB is an input which requires a high (+3~5v) to fully turn on the main power supply and pfc circuit. SW pin also requires a high signal to turn on the 12V_VCC for the backlight circuit

                            Comment

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