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    SMPS mains input voltage question

    Good day folks. Today I had a rather interesting discussion with a former workmate of mine who is currently working on a cruise ship abroad and he had a bunch of TVs to swap. They pulled the old TVs from the cabins which supposedly run on 110v on this ship from what I gather and later on they tried running one of these on a 230v input and one of them popped when they did so...DUUH, wrong voltage is what I instantly told him, but he protested that ALL SMPSs should be multi-voltage...are they ?

    This may sound like a stupid question, since there's a friggin' label on the device which lists the input voltage range, but I'm interested in the electronic side ! Either way, most SMPSs I've seen take the full 100-240v range, so what sets these apart from those that have a fixed voltage (like these guys' TVs) or better yet, a switch to toggle between 230v and 110v mains input ? What could pop when over-volting a fixed input SMPS the way they did ? Those with a PFC booster seem to invariably be full range from what I've noticed, though even some Samsung TVs which do not have PFC are listed as 100-240v. I've seen this phenomenon on ATX supplies which have a BIG label on the bag saying "230v only" or, at the other end of the spectrum, those supplies with metal cases and terminal block connectors - the latter have toggle switches.

    EDIT: THIS is the supply of the VIZIO TV in question. The large cap at the left, rated for 220v vented BUT the TV ironically works fine on 230v I told him to replace it with a 400v one. Sure enough, the back of the case DOES say 110v, so could it be the only key factor is this cap ? Even stranger, now the TV doesn't work on its native 110v anymore but runs on 230v even with the bulged cap like that, which is NOT recommended, but they did it anyway, so I can only guess that with a blown cap AND the lower 110v input, the DC present at that cap is just not enough for the supply to run or has excessive ripple, but a higher 230v input results in just enough voltage for the thing to run.

    Thanks.
    Attached Files
    Last edited by Dannyx; 06-04-2019, 01:04 PM.
    Wattevah...

    #2
    Re: SMPS mains input voltage question

    that psu is such shit,
    look, the board was made for decent diodes on heatsinks and to be "cheaped" with regular diodes and smaller input cap!

    Comment


      #3
      Re: SMPS mains input voltage question

      I think the PSU would be good for 110/220V but a few parts changed to lower cost to rock bottom. Visio is pretty cheap looking out for pennies like the primary capacitor voltage.
      The MOV is probably the same voltage for either mains voltage.

      Is the cruise ship 50 or 60Hz?

      Comment


        #4
        Re: SMPS mains input voltage question

        maybe 400Hz

        Comment


          #5
          Re: SMPS mains input voltage question

          The 220V cap limits it to 110/120 VAC. When rectified the DC voltage will be in the 160V range. Double the input voltage, double the output voltage. If designed properly, the MOV should also be selected for that input voltage range, but maybe the P/S mfr cheaped out and used the same part as for a 220 VAC P/S, as redwire suggested.
          PeteS in CA

          Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
          ****************************
          To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
          ****************************

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            #6
            Re: SMPS mains input voltage question

            He put in a 400v cap and it's now working on both 110 and 230v, so it turns out that was the only key factor...
            Wattevah...

            Comment


              #7
              Re: SMPS mains input voltage question

              how much power is it using at 230V compared to 110V? Same? more? less?

              Comment


                #8
                Re: SMPS mains input voltage question

                should be half the current - so a new fuse is a good idea.

                Comment


                  #9
                  Re: SMPS mains input voltage question

                  Yes theoretically (that is the key word) it should be the same power, and hence should draw less current.

                  However it could be more (not properly designed for higher voltage) or less (theoretically the main switch should be more efficient under higher voltages) thus the curiosity of what the current power consumption is.

                  Comment


                    #10
                    Re: SMPS mains input voltage question

                    Originally posted by eccerr0r View Post
                    how much power is it using at 230V compared to 110V? Same? more? less?
                    Don't think he has a power meter available sadly, though yes, the science of SMPSs would tell us that the amps should be lower when the volts go up in order to achieve the same output power.
                    Wattevah...

                    Comment


                      #11
                      Re: SMPS mains input voltage question

                      That is a pretty interesting thing... I expected that MOV to be kind of getting pushed and such closer to clipping voltage than it should be, but looking at the model number it seems fine for the job. (I don't know a great deal about proper usage of MOV's, so I might be wrong..) I'll leave the info here if anyone that is more experienced has something to weigh in on, but to my untrained eyes, it is looking pretty good! Honestly, it looks like it's really only there for rather catastrophic overvoltage scenarios. Not at all as close to clamping voltage as I would have expected.

                      The datasheet is for the series, so search the model number TVR14561-D to find the line on it's specs.


                      “Men always seem to think about their
                      past before they die, as though they were
                      frantically searching for proof that they
                      truly lived.”
                      – Jet (Cowboy Bebop) -

                      Comment


                        #12
                        Re: SMPS mains input voltage question

                        MOV's are put in so the power supply passes regulatory testing. Mains transients are applied and the common-mode chokes can make spikes worse, so you will see an added a MOV and spark-gaps on the PCB.

                        The 14561 MOV starts conducting at 560V and lightning impulse clamp is 930V. Just coverage for the mosfet and PWM controller IC.

                        I think the PSU is designed the usual 85-264VAC and then Vizio saved $0.10 putting in a low V primary capacitor. They seem to be an crappy brand.

                        $17M class action lawsuit against Visio for their Smart TV spying on users:
                        "the suits claimed Vizio tracks consumers' behavior, including viewing history and content preferences, and sells this data to media companies for targeted advertisement purposes. These ads apparently didn't just show up on Vizio Smart TVs, but also on any other devices that were connected to the same Internet network.
                        The problem with this, the suits alleged, is that Vizio customers did not consent to their data being collected and disclosed to third parties and were not aware that this was even going on. "

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