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.
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
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.
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