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Genius Ultramatic R2-T3 remote,Need help identifying component

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    Genius Ultramatic R2-T3 remote,Need help identifying component

    This is out of a wireless (RF) remote for one of those power lift beds for seniors. Remote says "The Genius Ultramatic" on it, and is model #R2-T3 (03-680252-03), FCC ID: MG8-R2-T. Standard Motorola MC145026P encoder, which is functioning.

    I'm told the unit doesn't work. I don't have the bed that goes with it, so maybe it's the remote that's the problem, and maybe it isn't . . . Haven't actually found anything that's NOT working in it yet. Don't have a receiver, so can't verify that it's actually transmitting anything. However, when I hold the device near unshielded speakers, I hear buzzing in the speakers when I push buttons on the remote. So, presumed working.

    Anyhow, not a complicated circuit, but I'm trying to identify this component, which I would *guess* was an RF NPN transistor in a TO-39 can, but the pinout seems to be wrong based on the circuit layout (unless I'm not understanding something correctly). Every TO-39 RF transistor I've ever seen has the Base as pin 2, and this one seems to have the base as pin 3. Near as I can tell (radio is one of my electronic weak points), pins 1 and 2 are connected across the antenna and have heavier traces, while pin 3 seems to be the base, and has a skinny signal-style trace.

    Markings: a logo I don't recognize (a triangle with a concave curved lower side) and the markings "R 677 JM5".

    I've scanned maybe a dozen lists of manufacturer logos, couldn't find anything that was a match. Looks vaguely familiar, but I just can't place it.

    Searched for variations on the numbers, didn't find a match. There is such a thing as an NE677M04 and even a 2SK677, which are RF transistors, but only available in SOT packages. There's a BD677 Darlington, but not RF and not TO-39.

    See pictures. Yellow lines just show connections on the far side of the board, for easier understanding. The unit circled in purple is the unit in question.

    Another thing I find odd about this unit is that, although it's a radio transmitter, I don't see any RF oscillators of any sort. How does that work? Obviously the antenna will be tuned for a particular frequency, but what flavor of transmitter is this? Uses the "spray and pray" transmission method, apparently? Please enlighten me on the theory of what's going on in the radio section.
    Attached Files
    Last edited by Joe24; 07-13-2022, 01:50 PM.

    #2
    Re: Genius Ultramatic R2-T3 remote,Need help identifying component

    It's not a transistor, it's a SAW resonator. These are used for the transmitter circuit in the oscillator. R677 is Siemens/Matsushita 315MHz.

    I think you can't get far without having the receiver, to know if it's working.
    The remote looks OK - no broken solder joints or liquid spills etc.

    Comment


      #3
      Re: Genius Ultramatic R2-T3 remote,Need help identifying component

      .

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        #4
        Re: Genius Ultramatic R2-T3 remote,Need help identifying component

        If you can hear demodulated RF on nearby audio gear, then it's making RF.
        This is just simple OOK, the MCU pulses power on and off to the RF oscillator transistor, which ends up being the transmitter. Like Morse code.

        youtube video he says the keypads are problematic but it has a red LED? https://www.youtube.com/watch?v=2nWXdwxG9RA
        kinda strange they have no dipswitches for channel/device uniqueness. Think of all the grannies I could squish if I had one remote near a nursing home.

        I find 315MHz remote stuff, the receivers just use a simple trimmer cap (no SAW resonator) for tuning, and they drift off to the point the remote has really short range or just stops working. You might have to take the bed RX apart and see if it needs tuning or somebody barfed or peed on it lol.

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          #5
          Re: Genius Ultramatic R2-T3 remote,Need help identifying component

          Not sure if it has a rolling code or not… however it sounds like what redwire already said. Look at the receiver. Sounds like the problem is there.

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            #6
            Re: Genius Ultramatic R2-T3 remote,Need help identifying component

            Now I've got a bunch of reading to do! Thanks for pointing me in the right direction. I hate not knowing how things work. Where's bigclive to do a complete circuit analysis when you need 'im, lol.

            Yes, the red LED threw me at first too. You would expect it to come on when you press buttons, right? Wrong, it only comes on when the battery is low. It's just connected to a divider net and a Darlington array (circled in blue on the board pic above; bottom SOT is a diode, top 3 are NPN BJTs).

            There are actually 3 selectable channels, by a switch hidden behind a sticker in the battery box. So you can only squish 1/3 of the grannies at a time. Don't get greedy, save some for later.

            Cleaned a bunch of crumbs out of the button pads while I was in there, but that would at most have crippled a couple buttons.

            I'm going to mail it back to the guy, tell him the remote isn't the problem. Doubt he's going to mail me the bed, but who knows. Maybe it's something simple like mismatched channels.
            Last edited by Joe24; 07-13-2022, 10:55 PM.

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              #7
              Re: Genius Ultramatic R2-T3 remote,Need help identifying component

              Just match the frequency to a different bed and see if it works?

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