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TDX Powerchair suddenly went dark

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  • TDX Powerchair suddenly went dark

    Hey everybody. My TDX Powerchair suddenly went dark; no power at all is going to the joystick. And its not the joystick cable. We checked. Where is the circuit breaker on my chair? What could cause such a travesty?? In my 25 yrs of chair-use, I've never had this occur.
    May the fetus you save be gay

  • #2
    Did you get it figured out? I can't even help here but I've had joysticks just straight up crater in the past. No warning, just pop, done.

    Hopefully yours isn't that.


    • #3
      Looked at the TDX SP owners manual and could NOT find a single reference to breaker. I'm surprised if you don't have a main breaker...but there is no reason your chair has to have one. It is a safety feature IMO. They are usually down low on the rear of the chair.

      If my car went dark I'd start checking at the battery...when is the last time you cleaned the battery connections? How did you verify the cable is good? I'm no expert but if I understand correctly how some devices need the correct amount of current. Good Luck.
      "Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed." - Hunter Thompson
      T5/6 complete


      • #4
        Originally posted by Theophania View Post
        Hey everybody. My TDX Powerchair suddenly went dark; no power at all is going to the joystick. And its not the joystick cable. We checked. Where is the circuit breaker on my chair? What could cause such a travesty?? In my 25 yrs of chair-use, I've never had this occur.
        There's a fuse located in the battery compartment. It's encased in a generic "blob" of plastic IN a cable connecting the two batteries together (the 12V batteries are wired in series to develop the 24V power; the fuse just happens to be placed between them -- it could have been located, electrically, anywhere).

        You can verify that the fuse is working properly by checking the output of the battery PACK with a voltmeter. The output is the OTHER two battery terminals that are NOT tied to the fuse. These should read ~24V across them if the batteries are charged AND the fuse is intact. A reading of 0V means fuse is open. Something less than 24 (like 20) indicates a battery that isn't fully charged. You may see something as high as ~27V for a fully charged, "good" battery.

        Alternatively, you could check the resistance of the fuse (with an ohmeter) -- "0" ohms means good fuse, "infinite" ohms means open/blown fuse.

        As you probably don't have a voltmeter or ohmeter to perform these tests, you (or a helper) can get an approximation (GO vs. NOGO) of this by wiring a regular incandescent light bulb across the OUTPUT terminals of the battery pack. This isn't as hard as it sounds. BUT, you need to be careful with the following...

        Get a regular lamp (table lamp, desk lamp, etc.) THAT USES AN INCANDESCENT BULB. Turn the lamp on. Verify that the bulb illuminates when you have it plugged into the AC power (so you KNOW the lamp is good AND you know you have the lamp in the ON configuration).

        Unplug the lamp. Connect a length of wire to one of the TWO prongs on the plug (ignore the third GROUND prong if the lamp has one). Often, the prongs have a small hole in the end that you can exploit for this purpose. Make sure its a "reliable" connection (twist the wire tight enough that you can be sure it has made -- and continues to make -- contact). Connect the other end of the wire to one of these two OUTPUT terminals for the 24V output of the battery pack.

        Touch the *second* prong (NOT the one to which you've attached the wire!) to the other battery terminal. The lamp should glow dimly -- but noticeably. You should see a marked change in intensity when you make the connection and then when you break it.

        If you screw up (or slip!) and touch the "wrong" prong to the battery terminal, you will short the battery. This is *not* a Good Thing! If the fuse is intact, you will, at the very least, draw a spark. It could be a SIZEABLE one! Depending on the thickness of the wire you've chosen, it could also "weld" that prong to the battery (this is how electric welders work!). With nothing to break the connection, the wire will get warm and/or blow the battery fuse (if it hadn't been blown already).

        So, only attempt this if you have steady hands or a helper who can perform the test.

        Attached are some photos of a similar setup (though not the same as your chair).

        The first shows a pair of 12V batteries wired in series. The "output" is the two terminals (one on each battery) on the right; the fuse acts to connect the two other terminals together on the left. Your fuse will have longer wire leads connecting it to the batteries but it will serve the same purpose.

        The second shows the two prongs of the plug of a lamp being touched to the output terminals. In this case, the terminals are close enough together that the two prongs can bridge the gap.

        The third shows a closeup of a typical TWO PRONG plug (note the holes in the prongs).

        The fourth was taken in a darkened room to make the glow of the lamp more observable.

        [I tried to submit a followup post with a link to a page out of a TDX-SP service manual illustrating your battery pack, but the post appears to have disappeared. ]

        IF you discover that your problem is related to a blown fuse, don't just blindly replace it (or, worse, SHORT it out!). Instead, you need to discover what caused the fuse to blow in the first place!
        Last edited by automation; 05-25-2018, 07:22 PM. Reason: Fix order of photos; nope! apparently a bug in the site doesn't allow this!


        • #5
          For details about your (?) chair, please see


          • #6
            Photo of TDX-SP battery pack from service manual. Note the fuse is connected via pigtails to the RIGHT side of the batteries with the "output" of the battery pack running off from the LEFT side.