I have an old broken Canon PowerShot SD1100 IS compact point-and-shoot digital camera, and I'm trying to see if I can find where it broke. I thought it was in the lens deployment/retract mechanism but every gear I can find in that gearbox (center lower area of this picture) looked OK. Time to look around the interior of this lens assembly for another candidate.

Towards the front (left) I noticed I couldn't see out to the surface of my workbench. The shutter must be closed by default. There should also be an aperture control iris mechanism but it is currently out of sight. And finally I know there's a protective lens cap/door in the front somewhere. I think they're controlled by a FPC (flexible printed circuit) cable reaching down the side, its typical yellow color covered with a flat black coating to minimize reflection.

In fact, everything within this assembly has a flat black surface. It makes sense Canon designed this optical chamber to minimize reflection, but it makes taking pictures very difficult! This is why my teardown pictures have wonky exposure and level curves.

Anyway, back to the components: I know they must be down that barrel. But even if they had failed, I doubt they would make kind of grinding gear noise I heard. From my past camera teardown experience I expect them to be built out of thin sheets of fragile material. Hard to take apart without damage, and even if I'm successful, hard to reassemble without damage. I'll put them down as less likely candidates I will postpone for now and revisit later if I run out of other ideas.

Furthest left on this picture is the optical viewfinder assembly. Unlike a SLR camera, this viewfinder has its own independent optical path that points parallel to the camera lens. But I noticed when I zoom in and out, the viewfinder changes in sync. How does that work?

The answer are these grooves on the outside of the barrel that rotates as the lens zooms in and out. They control spacing of a few optical elements within the viewfinder as zoom level changes, keeping the viewfinder in sync. Very clever and, for the purpose of today's investigation, exonerates the viewfinder because there's no motor or gear here to make bad noises.

I then started looking at the rear (right) side of the assembly, where I noticed I couldn't see the sensor directly. There was a lens element sitting in front of it.

Next to the lens element was a silvery metal cylinder that I had thought was a capacitor to supply sensor needs. Then I noticed it had four wires on its side, so not a capacitor. This is a stepper motor! I have found my next candidate for investigation.