electrical schematic symbols

Discussion in 'General Electronics Chat' started by doinky, Aug 5, 2011.

  1. doinky

    Thread Starter New Member

    Jul 19, 2011
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    On a refrigerator schematic I am studying. There is a term i am not familiar with. It is called Tab. To test a voltage the instructions say test from J7-9 to Tab 1. The J79 is neutral on the board and Tab1 goes into the power board. It is a black wire. So I am assuming Tab means black something. Either the wire or the connection at the board. It is on the high voltage side which is 120 volts. Are there any good reading material on schematics, testing and power boards. Can't seem to find any information on this subject. Of course I could post a sample of the schematic I am looking at if need be. But someone may know what these terms mean. I assume J stands for junction, not sure and Tab, I have no clue.
     
  2. #12

    Expert

    Nov 30, 2010
    16,298
    6,811
    Tab might mean terminal block. Non-standard happens. If there was a note somewhere on the drawing explaining all the non-standard symbols, life would be easier.

    Just do a search for "schematic symbols" and you will get many pages of results.
    Don't forget to search for "images" of schematic symbols, too.
     
  3. hgmjr

    Moderator

    Jan 28, 2005
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    Can you arrange to post a picture of the symbol in question here on the forum?

    hgmjr
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,791
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    The most common item refered to as a 'TAB', will be a male spade connector which is soldered into the board, or attached to a module, or motor. The connector is for a female spade connector on the end of a wire.

    This is the most common reference, but not the ONLY reference for which 'TAB' will be used in schematics.
     
  5. doinky

    Thread Starter New Member

    Jul 19, 2011
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    That definition sounds good enough to me. Tab is a weird abbreviation for a terminal. But, that's O.K. with me. No need to upload a pic. Would still like to know if anyone knows of a good book or information about reading and testing power boards with AC and DC currents. I know that mostly comes with practice, but are most of these designs pretty standard, I mean a black wire to control board being common and a white wire being neutral. Testing! Things like that!
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    When it involves household AC (110V/220V). Treat black wires as if they are dangerous live HOT wires. Black color - like what people wear to a funeral when someone DIES.

    They may not be carrying AC, but until you know for sure, treat them as if they do. The WHITE wires are used for AC neutral connections. The AC neutral is normally connected to ground outside your house, but there are many conditions under which it can deliver just as bad a 'SHOCK' as the black wire, so treat it with the same respect as you would the black wires.

    Again, until you know for SURE, what voltages are on the wires, treat black and white wires like they are carrying live AC household voltages
     
  7. Adjuster

    Well-Known Member

    Dec 26, 2010
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    Don't assume anything about wiring colours. The systems are not the same in all countries, and possibly may vary between different types of equipment. They may be different in older installations. For instance, in my country the live wire in an appliance lead is at present brown, but once was red. Similarly, the neutral wire is blue, but was black (yes, really!). The ground wire is green and yellow striped, instead of the old green.

    The best policy is indeed to assume that all wires carry lethal voltage unless proven otherwise.
     
  8. doinky

    Thread Starter New Member

    Jul 19, 2011
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    0
    Well, sure! I understand that. The boards I am looking at have a high and a low side. 120 volts in AC, high voltage. 5 to 12 volts out, for the DC side, low voltage like fans and other DC things. I am getting somewhat familiar with some of the boards. There all a little different. There is a 120 volt side AC and a low volt side DC. There are connectors to the various components. Of course these are appliances, like refrigerators, washers, dryers, dishwashers etc... Only thing is I can't find a lot of information other than service manuals. There obviously no different than any other circuit board, except there proprietary. Made for specific design applications.
     
  9. debe

    Well-Known Member

    Sep 21, 2010
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    Would be a lot easier to post the circuit diagram of what your refering to, be alot easier to understand.
     
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