[TheOtherCliff]

Just thought i would chime in and add my experience to the discussion. I purchased the Amazon Revolution clone with the case and the yellow red black upright pins. Quality of the part looked good to the naked eye. Board was installed with a Ublox M8n GPS hooked to th eflexi port. After hours of messing with it I can confirm that mine not only has the bad barometer which makes altitude hold useless, and the Main port is not functioning at all. Board also is unusable in gps assist mode. It is impossible to calibrate in ins13 mode.  even with 20 satellites locked it dances and horizon falls and dips by 20-30%! I managed to get it up in the air in ins13 in rate mode and put the hexcopter into gps assist and altitude hold and it was hilarious to watch, the poor thing looked like it had cerebral palsy. It was shaking and dancing all over the place. So I removed all gps flight modes and turned basic mode back on.

Still... in Basic complementary mode it is super solid and flys like a champ! it is very smooth and fun to fly in Rattitude and rate settings.

i didn't have problems with the onboard mag. i t seemed to work fine. it would go to orange on full throttle but hold green most of the time.

It seems that baro can maybe be fixed by removing a tiny capacitor.

A friend got a Revo board with a bad main port and I fixed it by looking at main port circuitry.  There was a short in the small filter chip that could only be seen with a jeweler's loupe.

PFD moving a lot is usually bad mags.  That can be bad mag calibration (little known is that calibration is happening all the time, not just when you push the button.  You must not set it down or close to anything bad the whole time you are calibrating.  It can be bad wiring, but that usually only shows up when the motors are under hard flight load (props on).

[TheOtherCliff]

It's my understanding that the problem is with the Bypass cap, not the Vout cap.  It oscillates if the value is too large.

Can you identify this cap you speak of in the schematic below?
Hi-Res Image

C9 from pin 4 to ground is the important one.  Remove it and test again and let us know.

[JaeMelo]

C9 from pin 4 to ground is the important one.  Remove it and test again and let us know.

Removing that made things even worse. The altitude kept on increasing. I replaced that part with a brand new cap from spares and that didn't change a thing either.

[TheOtherCliff]

How much did it increase?  It should stop and level out after 5 or 10 minutes.
Did you use a 10nf when you put it back?  It depends on the type of regulator.
Also, I am extrapolating from a successful fix of a Sparky 2.

[Mateusz]

C9 from pin 4 to ground is the important one.  Remove it and test again and let us know.

Removing that made things even worse. The altitude kept on increasing. I replaced that part with a brand new cap from spares and that didn't change a thing either.

I would suggest to let it stabilize for a couple of minutes, when I turn my original Sparky2, altitude also increases at the beginning, baro must warm up. But the increases are getting smaller with a time and up to the point it stabilizes itself and measures altitude accurately.

[JaeMelo]

How much did it increase?  It should stop and level out after 5 or 10 minutes.
Did you use a 10nf when you put it back?  It depends on the type of regulator.
Also, I am extrapolating from a successful fix of a Sparky 2.

At first there was a 10nf cap and it was jumpy like usually and also slow to altitude changes. Once I removed the cap. the altitude started to climb up to 35meters at that point I just unplugged it so it had to been less than 5mins. I replaced the old cap with a brand new 10nf cap and it went back to how it originally was. Jumpy but a lot better then the constant climbing that I experienced removing it.

I would suggest to let it stabilize for a couple of minutes, when I turn my original Sparky2, altitude also increases at the beginning, baro must warm up. But the increases are getting smaller with a time and up to the point it stabilizes itself and measures altitude accurately.

35meters seems like a long increase. Even if this did eventually stabilize this wouldn't be a satisfactory fix for myself. I Really wish these cloners would just use the correct damn components lol. I honestly might just have to replace every piece from the regulator forward on the baro circuit one by one till I find the problem.

[ggrif]

FYI, just received a second Revo clone from Banggood's US store, all sensors bench test good.

Finally got the first one in a frame with V9 GPS, hope to do a bit of flying this weekend to check functionality.

[whirlygigg]

I bought two of these cloned Revos. One was from hobby king, the other came from a seller on amazon called hobby ace.

I think the baro is OK. The widget for barometer pressure varries .012 on both boards at room temperature. If I understand tbis thread correctly, that iz within tolerance.

I have not flown outside yet, but I did hover quite nicely in front of my cat's toilet for a while.

[TheOtherCliff]

.012 kPa pressure noise sounds like a good board. 

[soulreaper]

Glad i read this post.   Really dissapointed.  I currently fly a cc3d without any issues.  Was looking forward to getting the revo.   Does anyone sell a good revo?   Will some one eventually sell a good revo? 

[ggrif]

Several "good" Revo's (clones) are referenced in this thread and elsewhere in this forum. Take your pick.

[Joe_D]

Hello,
I bought a Revo clone from Fisher Hobby on Ebay, the baro error was in the +/- 3m range. Then I added a 10uF capacitor on the C29 capacitor  just beside the pressure sensor. The error is now within +/- 0.6m. Attached is a video showing how stable my tricopter is hovering in velocityroam mode.
Joe

[TheOtherCliff]

Excellent news on another way to fix a bad baro!

I am pretty sure that I have heard of both good and bad baros from at least one seller.  I have also seen two versions of the Revo being sold with very slightly different layouts; in particular, one has a component so close to a mounting hole that it interferes with a standard M3 nut or standoff.

I personally have seen a bad baro on a Revo from Thanksbuyer and on a Sparky2 from Goodluckbuy.

[sprockett]

Im getting 40-80pa swing, can anyone show me where the C9 capacitor is on the board

[f5soh]

Look at assembly layout:
https://bitbucket.org/librepilot/librepilot/raw/cefcacbbcf7d7fbfa27aaf13c0bae909562ec869/hardware/Production/OpenPilot%20Revolution/Assembly/Revolution%20Assembly.pdf

Also schematic:
https://bitbucket.org/librepilot/librepilot/raw/cefcacbbcf7d7fbfa27aaf13c0bae909562ec869/hardware/Production/OpenPilot%20Revolution/Revolution%20Schematic.pdf

C9 is a bypass capacitor on pin4 of regulator.