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  • Schematic question

    Can someone have a look at this scem ? I was told there was a thermistor in here that will turn the 2 fans on and off. I dont see one...unless the LM7824 is used somehow ..but isnt that a voltage reg. ? Page 2 .
    Just curious !
    Attached Files

  • #2
    What's this thingy on the fan circuit labeled 9L122uh below. Never seen that component symbol before. There's another on the power switch without a moniker.
    Attached Files
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #3
      I don't see it. It could be there, but I don't see it. I believe it's probably hooked between J18-1 and J18-2 on the schematic and probably mounted on a heat sink. Those 2 points are to the right of the LM7824 on the schematic.
      "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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      • #4
        Originally posted by Chuck H View Post
        What's this thingy on the fan circuit labeled 9L122uh below. Never seen that component symbol before. There's another on the power switch without a moniker.
        Maybe coils for EMI supression?
        "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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        • #5
          thought ferrite bead ??

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          • #6
            The thermal switch connections are marked as the Dude said.
            (the switches themselves are not shown))

            J18-1 J18-2 is connected to a 65 c switch.

            J18-3 J18-4 goes to a 90 c switch.

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            • #7
              Originally posted by Jazz P Bass View Post
              The thermal switch connections are marked as the Dude said.
              (the switches themselves are not shown))

              J18-1 J18-2 is connected to a 65 c switch.

              J18-3 J18-4 goes to a 90 c switch.

              the dude is correct ! i traced it through the amp and found those 2 parts hidden under a big heat sink

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              • #8
                Originally posted by Chuck H View Post
                What's this thingy on the fan circuit labeled 9L122uh below. Never seen that component symbol before. There's another on the power switch without a moniker.
                It's possible that the part is a dual coil inductor made by Murata.

                https://www.google.com/url?sa=t&rct=...VQGXXOREepIZ0S

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                • #9
                  Most probably.
                  If labelled jtīs a commercial product; if unlabelled itīs probably aplain generic ferrite bead.

                  Although the commercial products may be as simple as same ferrite bead or slightly larger one with a single or dual wire loop through it.

                  The difference being (maybe, wild guess follows) that a human must pass a wire through a ferrite bead while one with a wire preinserted (and with ends pretinned) can be inserted in a PCB at the rate of 1200 an hour or something like that.

                  Mighty Terminator will rule the Earth.
                  Juan Manuel Fahey

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                  • #10
                    Originally posted by J M Fahey View Post
                    Mighty Terminator will rule the Earth.
                    But he won't build "my" amps (though he may hunt me down and scrub me into red goo on the asphalt )
                    "Take two placebos, works twice as well." Enzo

                    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                    "If you're not interested in opinions and the experience of others, why even start a thread?
                    You can't just expect consent." Helmholtz

                    Comment


                    • #11
                      Originally posted by J M Fahey View Post
                      Most probably.
                      If labelled jtīs a commercial product; if unlabelled itīs probably aplain generic ferrite bead.
                      That sounds real plausible but what's up with those reference designators, I don't ever think I have seen a schema like that before... kind of cryptic. 9L122uH the 9L is the ninth inductor maybe? the schematic uses things like 8C for a capacitor and like that. Is 122 micro henries reasonable for that application? I think that's the value, it's a composite reference designator/value marking maybe... yeah strange... no! I see it now! the (9) is the circuit group the next two are the reference designator (L1) and the last 4 characters are the value (22uH)... yeah, strange.
                      ... That's $1.00 for the chalk mark and $49,999.00 for knowing where to put it!

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