Question Vacuum cleaner wont turn off and motor pulses high to low

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GabrielKnight01

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Jun 9, 2016
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this is a board from a vacuum cleaner it has a pulsing output to the motor that's going from high to low so the motor is going from low rpm to high rpm and turning the pot in the off position does not turn it off, I forgot to write down which side of the pot is being used for off so I have checked to see if turning the pot all the way up or down works but it doesn't it is still pulsing high to low. I'm not sure if its the triac with three legs on the heatsink because this is just a gate to turn it on, so I checked the pot out of the board and on the two neutral output pins its operating with a high resistance on one side and a low resistance on the other side and vice versa when turning the pot to the other direction while in the middle setting the two pins are the same but the output is still pulsing in any direction of the pot, I checked the electrolytic cap with just a multimeter and its in range of 330uf but I'm not sure about its ESR I don't have an ESR meter, all the diodes seem fine in board, I haven't checked the two yellow caps yet because I thought I could see if the triac would likely be the problem but I cant understand why because I only removed this board and it was working before the only thing I can think of why is I bumped the pin that goes in the center of the pot that's why I checked it out of board I only understand a little about electronics can someone look at the circuit and tell me if the pot is meant to have a high resistance on one output and a low resistance on the other output as I have seen some pots do it this way

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