Reed switch for dishwasher

Discussion in 'General Electronics Chat' started by rjnkanwal, Nov 18, 2015.

  1. rjnkanwal

    Thread Starter New Member

    Oct 24, 2015
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    I have a Bosch SMS69-L22GB dishwasher. The reed switch for flow meter has failed. it should be N/O but it now in closed position all the time. There are no specifications about this reed switch and the one supplied by bosch costs £19. After doing google search I got this info from digikey site that normally it should be 200v, 10w, AT 5-25.
    The reed switch in my dishwasher is 14mm long and 2mm dia. Total lenghth is 30mm. I can get a reed switch of same size and within the above speccs. But two things are concerning me is that total length is 44mm and it says dc volt. If I cut the contacts to 30mm, would it change the AT significantly or not.
    Also does it matter if you use it in ac or dc. Any help would be great.
    Thanks.
    raj
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,974
    744
    Cutting the length wont alter the ratings, a switch rated for DC will work ok on AC as the supply is reversed automatically, as long as its the same voltage and current rating.
     
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  3. rjnkanwal

    Thread Starter New Member

    Oct 24, 2015
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    Thanks Dodgydave. I don't have the actual specc of the current reed switch. I am just going by the info on digikey site about dishwasher reed switches. I will just give a try and see what happens. I believe I can''t do more damage as there are other sensors which would stop the dishwasher from operating if something is not working as it should. If the replacement one does not work then I will have to cough up £19 which to me is too much price for something which cost pennies.
     
  4. rjnkanwal

    Thread Starter New Member

    Oct 24, 2015
    7
    0
    Ok another question dodgydave.
    According to digikey, possibly correct reed switch would be MK23-66 with these values
    STANDEXMEDER

    REED SWITCH, SPST-NO, 0.5A, 200V, SMD

    REED SWITCH, SPST-NO, 0.5A, 200V, SMD; Contact Configuration:SPST-NO; Switching Voltage Max:200V; Switching Power Max:10W; Contact Current Max:500mA; Contact Resistance Max:0.15ohm; Operate AT Min:10AT; Operate AT Max:15AT; Switch Mounting:SMD; Product R
    The one I got is same specc apart from the max switching voltage which is 100v max. I soldered it on to the pcb anyway and dishwasher has completed a full cycle successfully.
    Does the max switching voltage can cause problems in the long run i.e. shorten the life of reed switch or something else?
    Thanks
    Raj
     
  5. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
    619
    Most likely would decrease lifetime. The contacts on the switch with a lower voltage rating could be closer together which could cause the shorted contact problem again; only more quickly this time.
     
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  6. rjnkanwal

    Thread Starter New Member

    Oct 24, 2015
    7
    0
    Thanks dl324. I'll order the STANDEXMEDER MK23-66 which is recommended for dishwashers.
     
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