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Repairing Rancilio Espresso Machine - ID Trimmer Pot

Discussion in 'Troubleshooting and Repair' started by Michael S Payne, Jul 21, 2015.

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  1. Michael S Payne

    Michael S Payne

    10
    0
    Jul 21, 2015
    Hi everyone, my espresso machine is acting odd and I am pursuing help in

    1. identifying a trimmer pot
    2. determining if the problem is the trimmer pot


    I have an espresso machine that changes the pressure in the boiler frequently when I turn it off then on again. The pictures below shows the board and a zoom on the board to help identify the trimmer pot. That pot is how adjustments are made to the boiler pressure; however, symptoms are as follows: the bar changes significantly just turning the machine off for the night and tuning on again the next day. When I adjust the trimmer, I sometimes barley turn the pot and it changes the bar an enormous amount and other times I turn the pot a lot and it barley changes the pressure. This makes adjusting tedious and time consuming. This adjustment should not have to be made, much, if at all, yet I usually have to do it multiple times each week. Sometimes it adjusts quickly and I am up and running in five minutes. Other times, it takes 20 minutes because of the crazy variations I am getting. I am assuming this is an issue of the trimmer pot going bad? I took these photos to get your help in identifying what type of pot to purchase to repair it. I added the other information to get your opinion as to whether or not I am going in the right direction. FYI, the circuit board is 10 years old. It is a Rancilio Epocha E1 Espresso Machine. I have a local electronics guy who offered to solder the new pot on, if that is the problem. A new board is over $800 and the only option the manufacturer offers. They where not able to tell me what pot to get, so I am appealing here for help in an attempt to repair the board. Thank you, Michael - Penguin Yell Coffee. closeup.jpg Wide.jpg
     
  2. shrtrnd

    shrtrnd

    3,781
    499
    Jan 15, 2010
    That's a Bourns trimpot. Look on the side of the pot for the model number, then add the 'W502' for the entire part number.
    For example:
    a Bourns Model 3296W-502 is a 5K ohm trimpot.
    Yours is definately 5K ohms. It's important to know the model number on the side of the pot to get the correct size pot, pin alignment/spacing, number of turns, and adjustment screw location.
    There are several Bourns models (3299, 64 series, 3292, etc...), all different physical sizes.
    But you're right, the pot controls other circuit functions. Could be the pot, could be something else
    that the pot drives. The pot is a couple bucks to find out.
     
  3. Michael S Payne

    Michael S Payne

    10
    0
    Jul 21, 2015

    Thank you. It is in fact a 3296W-502 5K and I just ordered it. Hope this was the problem. Thank you for your kindness in helping me.
     
  4. Michael S Payne

    Michael S Payne

    10
    0
    Jul 21, 2015
    In my haste, I purchased the same part number, but a different manufacturer. I bought "BENTENG" instead of Bourn. Will this be a problem? If so, I will eat the $3 and buy the right one. Here is the item I bought http://www.ebay.com/itm/221316723445
     
  5. shrtrnd

    shrtrnd

    3,781
    499
    Jan 15, 2010
    Haven't heard of the mfgr. What you will find when the pot arrives, is if it's the correct size and if the pins are aligned to fit the holes for your printed circuit board.
    Maybe the BENTENG company used the Bourns part number to signify an equivalent replacement?
    I'd just wait and see what you get, and if it fits, use it.
    Your symptoms really sound like the pot is bad to me. I may be wrong, but I'd switch the pot and see if it solves your problem all by itselff.
    A lot of companies make the same size pot as the original,so you don't NEED an exact replacment.
    Good luck with the fix.
    If you've still got a problem after replacing the pot, give us a shout and somebody will help you.
     
    davenn likes this.
  6. Michael S Payne

    Michael S Payne

    10
    0
    Jul 21, 2015

    will do. Thank you again.
     
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