Relays, Convention for terminals?
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  1. #1
    Join Date
    Nov 2008
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    Northern California, foothills.
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    Relays, Convention for terminals?

    Relays often scare me a bit because they almost never
    have a diagram on them about what their terminals
    do--power, common, coil, normally-open, normally-closed.
    And on the older units that have them, the schematic
    is often unreadable or not there or not helpful.

    Is there a conventional way that terminals are
    numbered and assigned duties on relays so
    that I don't need to depend on any information
    at the unit? (If so, could you please tell me what
    that is?)

    Thank you.

  2. #2
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    Apr 2012
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    winnipeg
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    none I am aware of.....
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  3. #3
    Join Date
    Dec 2002
    Location
    Houston,Tx.
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    15,778
    Some relays have the 24 volt terminals soldered, and it's very easy with an ohm meter to figure out what is NO and NC, hope this helps.
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  4. #4
    Join Date
    Dec 2007
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    4,661
    I have 4 different relay on my van and they all have some form of ID for each terminal.
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  5. #5
    Join Date
    Nov 2007
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    Mississippi
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    What about a nine pin socket relay? These are the ones that I struggle with.

  6. #6
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    Central Indiana
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  7. #7
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    Mar 2012
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    My house is in Texas..
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    Or like this

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  8. #8
    Join Date
    Nov 2007
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    Mississippi
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    Quote Originally Posted by 5thRoot View Post
    Like these?
    90-340 is stamped on the front.

  9. #9
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    Nov 2007
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    Mississippi
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    Quote Originally Posted by socotech View Post
    90-340 is stamped on the front.
    The schematic I mean.

  10. #10
    Join Date
    Jan 2010
    Location
    Toronto,Ontario Canada
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    I often replace the mushroom relays for the brown ones all the time. Much more easier to work on then the clear ones. Georgelass it just takes time to get use to them. i was the same way, bt after seeing it many times im not too afraid of them anymore. I hate the old sequencers that york has. those thing never have any scehmatics on them!! but from experience, i know what to look for to see what i need to replace those hunk of junk....

    When you look at the see thru ones u can actually see the terminals if not most of them have a scehmatic printed on the side or front of them.
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  11. #11
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    Nov 2006
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    Quote Originally Posted by 5thRoot View Post
    Like these?
    This is a type 91 relay. The connection diagram is embossed into the plastic.
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