Servo Driver Circuit (possibly dead?)


 
J

JayC

TVWBB Fan
I have two different servos that are not working properly and I figured since they both used to work and now neither work, something is wrong with my HM 4.2.

When I have the servo apart and set temp so that the servo is either 0 or 100%, it will go to either position without issue. Together, there is not enough torque. I thought it was binding but it's not, it's just like the servo lost it's torque. It doesn't "fight" when it's in position either, or in other words, when it is in position and I try to manually turn it there is little torque required to move it--almost as if it's unplugged.

I figured since it is moving maybe I'm getting enough voltage to move it but the circuit is damaged but then I'm not a EE so I didn't know if that would be possible or not. Any ideas? Thanks!
 
FYI, recent HM software releases have the servo configured for a move and rest scenario, it only stays powered on (with holding torque) for a few seconds after each movement.
How is the torque when the servo is loose in your hand? When you put the servo in its mount is it a really tight fit, that can cause the servo to bind and make it seem as though it is stuck or has lost torque.
 
RalphTrimble said:
FYI, recent HM software releases have the servo configured for a move and rest scenario, it only stays powered on (with holding torque) for a few seconds after each movement.
How is the torque when the servo is loose in your hand? When you put the servo in its mount is it a really tight fit, that can cause the servo to bind and make it seem as though it is stuck or has lost torque.
Click to expand...

Thanks, Ralph. That's exactly the problem I'm seeing. They work fine when it's just the servo and no damper.

However, since my dampers are so large they are not the smoothest running and can still be in motion after the time out during movement. Unfortunately, when it times out they tend to get stuck now (mostly when it's wide open so the temperature runs away).

I'm assuming that I can't toggle this "feature" on/off huh? I will have to roll back or get a more powerful servo that will overcome my damper design. It's looking like I need to solder up that extra 4.2 that I have in a box and that way I can experiment with this firmware and the previous one.

I will say it seems like the servo has less torque than it did before too. It's much slower even outside of the damper and easier to stop.
 
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You can try powering the servo from a dedicated 5v source and just let the HM take care of sending the data signal to control the servo.
 
Steve_M said:
You can try powering the servo from a dedicated 5v source and just let the HM take care of sending the data signal to control the servo.
Click to expand...

So you're saying that I'd put +/- 5VDC on the Red and Brown, respectively, and then send the data signal on the orange on the MG90S Tower Servo everyone uses? Could I steal the 5VDC from somewhere on the HM board and just break the traces on board and run wires to the jack?
 
I can't get the fight back in my servo. When I was v13, my main page said:

OpenWrt | OpenWrt Attitude Adjustment 12.09 | Load: 0.03 0.04 0.05

So I tried to revert to backup image from February of 2015 and now my current load says:

OpenWrt | OpenWrt Attitude Adjustment 12.09 | Load: 0.10 0.04 0.04

but in System/Software/linkmeter it still says v13 so apparently the archive isn't changing everything and this servo timeout feature is still plaguing me.
 
Never mind! I figured it out! I'm flashed back to trusty old v12! Looks like I'll be smokin' again this weekend!
 
WAY MORE POWER! I got home after flashing my HM from work and realized that now that I'm back on v12, WAY MORE POWER in the servo. It felt like it was just barely moving in v13 but just flies in v12. When it bumped me in v12 (fingers, not in the canister) it just gave up like my 4 year old. The v12 feels like my buddy that is 50lbs bigger than me and 3" taller hitting me with anger. I'm not sure if that was the desired affect in v13 or not but if you're having problems, go back to v12 and they should be fixed.
 
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