Dead multiplexer?

Wondering if anyone might have experienced a problem that I'm having. My ArduPilot has been working fine, but yesterday, the servo outputs suddenly quit working. After doing some troubleshooting, I think I've narrowed the problem down the the multiplexer (74ACT157). It gets power, and gets a proper signal from the failsafe, and I found a 50 Hz signal on the inputs. However, the outputs are always low, at 0V.I've been using a 4-cell, 4.8V receiver battery to power my setup. When fully charged, it gets up to 5.3V, which should be safe for the multiplexer. Maybe I shorted out one of the outputs, or zapped it with static? Anyone else had a similar problem?
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  • 3D Robotics
    Did you switch the solder jumper to BATT?
  • Developer
    Using a small switching dc-dc converter is te way to go, I don't think your 4.8 v battery caused the problem, I would suspect that too much current was sourced by mux chip, try to replace it .
  • I'm setting this up in a glider, thus I don't have an ESC. My plan is to use a 2-cell LiPo battery with a 5V regulator connecting it to the receiver and ArduPilot. I figured that a 4.8V battery would be safe to use for testing before I made that.

    I'm not convinced that it was the battery that caused the problem. I measured the battery on a full charge to be 5.3V and the max supply voltage on the multiplexer is 5.5V, so it should have been fine.
  • 3D Robotics
    BTW, this is the first time we've heard about the issue, and nearly 1,000 ArduPilots have been sold. So I think it's safe to say that it's rare to the point of being unique.
  • 3D Robotics
    Just out of curiosity, why are you powering it directly with a battery? We set up that power regulator so you could, but to be honest we could never think of a reason why anyone would want to when it's just as easy to power the RC Rx and then power the board through that. What's the advantage of doing it your way?
  • No, I don't think this is the consensus, I haven't heard of many people having this issue. That said, if you want to power it with a battery (and not through an ESC), it is probably a good idea to put a regulator in between. I've been planning on using mine with a 2-cell lithium and a switching regulator to step the voltage down, but haven't gotten to that yet.
  • Developer
    great I just ordered one.....Hope this isn't the consensus on all of them....
  • I think I have a similar problem I also use the rx battery. I ordered 2 new boards
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