ice maker control relay

Discussion in 'General Electronics Chat' started by seesoe, Mar 5, 2011.

  1. seesoe

    Thread Starter Active Member

    Dec 7, 2008
    99
    0
    hello i have the following control board for an ice maker
    http://www.nt-ice.com/product.php?p=manitowoc_76-2907-3&product=170648

    it is a straight forward board, its basically ic's controlling 3 relays.
    one of the relays is for the ice makers compressor. that relay isn't getting proper power, one leg has jumping voltage and the other leg has nothing.

    i desolered that relay and tested it, and it works fine.

    im not an expert in circuits but i did know to check the corresponding the transistor. i plugged it into the voltmeter and it gave me a HFE value of 230, actually i tested all 3 (got them mixed up now) they gave values of 230, 220, 220, is that enough to say that the transistor is ok, or could it still be faulty? and cause what is happening?

    3 NPN transistors MPSA05
    3 SPST 24VDC relays
    ic 1 - 18 pin unmarked
    ic 2 - 93LC46 / I/p SCW / 9921 (Serial EEPROM?)
    ic 3 - PM94BR / LM / 2904N
     
  2. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    Hi seesoe, Is the compressor relay clicking on & staying on or chattering? Since in the picture of the board the 3 relays all look the same, i would try swaping the compressor relay with one of the others & see what happens. It does help to post sharp & clear pictures of you actual board you are trying to repair.
     
  3. seesoe

    Thread Starter Active Member

    Dec 7, 2008
    99
    0
    hi debe, thank you for the reply,

    the information i was told was based off of what the refrigeration technician told me.

    he actually said the whole board was bad, the relay for the compressor was doing funny things, and wanted to charge me $400 for a new board (it is really $300, the put a $100 markup on it) and another 150 to change it out.

    so of course i told him no, and started tracing components from the relay to the ic and see what could be the issue, everything seemed fine. so i soldered everything back and hooked the board back to the ice maker and found out that the board was working perfectly and the compressor relay was clicking and providing power out just fine. i kept tracing the output of that relay, and found that it connects to an external (from the board) relay. it is a 120vac 18a spst relay, i found out it's coil went bad and no longer contacting. i quickly replaced it with a radioshack relay for a couple of buck and everything worked fine.

    how about that?
    thank again
     
  4. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    Glad you fixed it, so if he replaced the board it still wouldnt have fixed the prob & cost you more!
     
  5. seesoe

    Thread Starter Active Member

    Dec 7, 2008
    99
    0
    exactly, probably another $200
     
  6. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    Uh oh !!!....:eek:...I feel a bad attitude attack..............

    Refrigeration "technician" huh ?? sounds like another one of those glorified part changers to me :p

    One of the disciples of .......

    " if you can't dazzle 'em with intelligence.........Baffle 'em with baloney"........:mad:

    people like that should be slammin' burgers @ Mc Dumdums for min. wage.
     
    Last edited: Mar 9, 2011
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