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Proper part for dc voltage converter.

Discussion in 'General Electronics Chat' started by Kenny'sid, Nov 6, 2017.

  1. Kenny'sid

    Kenny'sid New Member

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    Hi I need to order the broken potentiometer for my China converter damaged in transit. I can solder it to the board, no problem, but that's about as far as my knowledge goes in this area.

    I bought these, no big loss if they are wrong ....

    https://www.ebay.com/itm/5pcs-3296W-503 ... SwUuRZ2tox

    ....and then I saw a bunch more of different ohm values, meaning I probably ordered the wrong ones unless I got lucky.

    Question, how do I tell what ohms mine is by what is written on it? What I could read on the side of the ones at the link are the same as mine..at least the larger letters, but I see now I have an "M 104" and a "101 T" stamped on the top of mine. Not sure if that's any help or not.

    Here's the converter if needed

    https://www.ebay.com/itm/1500W-30A-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    Can any of you help me get the right part if I don't have it already?

    thanks :)
     
  2. dknguyen

    dknguyen Well-Known Member

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    Something like 123 probably means 12000 ohms, where the each digit stand for (1)(2)x10^(3) ohms.

    If the pot is being used in the supply for adjustment as a voltage divider, then the absolute ohms doesn't matter too much as long as it's not too high or too low. You don't want the resistance so low that too much current is being drawn so the resistor or the feedback pin in the supply overheats, but you don't want the resistance so high that not enough current flows through it to produce a reliable, stable voltage. Anything between 4.7K to 20k would probably work. Going outside that range it starts to get a bit iffy but it could work just fine depending on the supply. Give your 50K pots a shot. 50k is probably near the limits of what it could work with.

    This is not the case if it's being used as a variable resistor (where one end is left unconnected), but this is rather unlikely.
     
    Last edited: Nov 6, 2017
  3. Kenny'sid

    Kenny'sid New Member

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    Thanks for the fast reply, DK. The application for the converter is to step up a 36v li-ion battery pack to 48, there are three of these on the unit, and I haven't gotten with the guy on adjustments yet but in case that helps...

    Here is the title to the listing I bought::

    5pcs 3296W-503LF(50K ohm) 3296W-503

    I have found this on the side after a closer look, a 3, some similar type squiggle (that was the best I could do with the keyboard) then a 1 at the end with a 2 in the center/underneath the squiggly line : PS, the 2 won't go to the right about 3 spaces as it should but you get the idea.

    3/\/\/\/\1
    2

    Most of what you stated is over my head, but in the end, are you saying the ones a the link, the ones I ordered, will most likely be fine?

    If not, and since it takes forever for these to come from china, probably best I order 1 now that we know will work. If post a link to the ebay list of them would you mind pointing the proper one out to me? Of course I want the least expensive/lowest quantity. I'll go ahead and post that link, and I know some folks don't like to click links from strangers so, just advise so I can find it, if that the case...no worries. I ask you to because I'm just that stupid on this stuff and want to be sure to get the right one.

    https://www.ebay.com/sch/i.html?_fr...2.TRC2.A0.H0.TRS0&_nkw=Potentiometer&_sacat=0
     
    Last edited: Nov 6, 2017
  4. dave

    Dave New Member

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  5. dr pepper

    dr pepper Well-Known Member Most Helpful Member

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    If you measure with a multimeter set to resistance pins 1 & 3, that will give you the pots resistance, 50k ohm on the ones you ordered, the original one should be similar, if not you got the wrong ones.
     
  6. dknguyen

    dknguyen Well-Known Member

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    Yes. If you find it is not reliable or not doing what you want, then try another one between 4.7K and 10K.
     
  7. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Why do you order cheap junk from China? The trimpot is made properly by Bourns company who invented it. It is stocked locally by Digikey. If I order one (you do not need to buy more than one) before 8:00PM then it is delivered to me the next morning.
     
  8. Kenny'sid

    Kenny'sid New Member

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    I'm not that good with a multimeter, but I will give that a try. Thank you

    I just checked there and it seems to be discontinued. I'm assuming it's a trimmer but you are calling it a trim pot, but I could not find that there. See, it's just about impossible for me to even find something like this without pics as a reference, but if the price wasn't to bad and it was available at digikey, I would have considered it.

    Thanks for the tip...may consider them in the future...beats waiting a couple of weeks.

    I found a 5 and a 10k on ebay, so guess I'll order the 5 and have a pretty good chance of one working

    Good deal, and thanks, everyone.
     
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    I entered 3296 in a Digikey search for active parts and found thousands of Bourns trimmer potentiometers in stock that look like the Chinese copy. $2.41US each.
     

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