Dead BBB confirmation and stripped servo?


#1

@Walt_Holm @Brian_Grau @Support
Hi Brian,
Hi Walt,

Hope everything is going well with the trident. Sorry to drag you back to the past but I need some advice with my 2.7 ROV.

I took my 2.7 for a dive today. The dive went well but after the dive I was doing some maintenece and have a few problems.

I couldn’t get the full range of movement from the camera servo, it tilts up without a problem, but won’t tilt down (chatters). It will move without the camera assembly, but even with the slightest pressure from my finger it won’t tilt down. I’ve put some machine oil where there are moving parts too. I’m guessing the gears have stripped and it needs replacing, or could it be something else?

While I was trying to fix this I think I fried my BBB. I was putting the electronics assembly into the tube and I heard the ESC’s beep (I guess it reset).

I have fully charged batteries, the homeplug lights are good but no cockpit. When I remove the BBB and plug it into USB power I get one flash from the power LED and then nothing. It does the same thing if i boot from the eMMC or SD card. No lights on the BBB ethernet socket, and no user LEDs either.

Do you have any suggestions for getting it working again? or should I just replace the BBB and servo?

Thanks
Brendan


#2

Hi @Brendan:

Sorry to hear about your 2.7. If I remember correctly (wow, it’s been a long time since I’ve driven a 2-series), the 2.7 and earlier models were kind of sensitive to how well the tilt platform was aligned, and could easily strip the servo gears. With my 2.7 I tried replacing the stock servo with a metal gear one, and all that did was burn up the servo when the tilt stage jammed. In the 2.8 we made some major changes to the camera system so that the tilt stage would not jam.

As for your situation, I can’t think of any obvious things to do other than change the BBB and the servo. If you’re handy with electronics, change the servo first, and then very carefully make sure the tilt stage is aligned, and test the whole tilt mechanism with a servo tester. You should be able to do this with the E-chassis in the tube but one end cap off (so that you can get at the servo wires.) Once you’re happy with the camera and servo alignment, then it will be an easy process to pop off the BBB, replace it with a new one, and connect the servo to the controller board. That way you won’t risk your new BBB or your controller board while you’re fussing with the alignment of the tilt stage.

Let us know how things turn out.

-Walt


#3

Hi @Walt_Holm

Thanks for the advice, I’ve ordered a new servo so I’ll test it with a spare arduino first.

The camera system is pretty well aligned and moves easily without the servo arm installed.
Even when the camera was facing straight up - so there was no weight, the servo couldn’t push it over.

I’ll order a new BBB and will keep you posted if I run into any difficulties.

Cheers,
Brendan