I tried and failed to fix a broken gear I found deep inside my old broken point-and-shoot digital camera. I tried to take it apart non-destructively because there was a small chance I could fix it. Unlikely, given the tiny mechanisms within, but there was a chance. I thought it was more likely that I would find a fault that I couldn’t fix, or that I couldn’t find anything at all, at which point I would proceed to completely disassemble it for the sake of curiosity.

But now that I have tried and failed to fix the fault, I found myself unwilling to move on to destructive disassembly. I didn’t feel it was a “well, that’s that” situation. This feels just barely beyond my reach, and I should be able to think of something in the near future. I’m not ready to give up yet!

This leaves me in an awkward state: I don’t have any more repair ideas to try right now, and I have a lot of scattered camera pieces in front of me. Their current positions on my workbench are a direct reflection of how those pieces fit into each other. If I sweep them into a bag, I will not be able to put this thing back together. With that in mind, I decided to reassemble the camera so I could clear my workbench for other projects until I return to this thing with a new idea.

Manually turning gears tiny bit by bit, I retracted the lens mechanism before putting it back together. Then I electrically connected the assembly to the rest of the camera in a test run configuration:

Typically the lens assembly is in the middle, blocked in by the flash module and other pieces. I don’t want to assemble/reassemble all adjacent pieces every time I want to test something, so I came up with this arrangement. It allows every electronic connector to be plugged in to their right places, but leaves the lens assembly dangling out front so I could easily unplug it. This configuration is a lot more awkward than doing the same thing with an inkjet printer, because every cable is short and have very little slack.

A rear view of this awkward arrangement. This could be a lot neater if there wasn’t a tiny cable connecting LCD to flash module in addition to the wide LCD cable at the bottom. But this is the view I have for verifying I still get “Lens error, restart camera” on screen. While I haven’t fixed the camera, the good news is I haven’t catastrophically damaged anything else either. The bad news is that my laboriously hand-retracted lens was deployed again during startup. Gah! Given the effort it took to manually retract, and the risk I’ll break something if I were to go back in and do it again while frustrated, I decided to just leave the lens extended and resolved to be careful putting this away.

An hour later, I have the camera mostly back together. There were a few pieces of double-sided tape that didn’t hold as it used to, and there were two plastic clips I inadvertently broke when I pulled the lens assembly apart. At the end, I found myself with one extra screw left over despite my notes, pictures, and physical reminder via workbench layout. I don’t remember where this one screw was supposed to go, and couldn’t find a likely place for a missing fastener. Ending with a single extra screw isn’t terrible for a beginner but it shows I have a long way to go before I can be trusted for actual camera repairs!

I have a broken point-and-shoot digital camera of circa-2008 vintage, and I think I’ve found the point of failure: a small red gear who is supposed to turn a lead screw but has cracked open.

Without its friction fit grip on the shaft, it now just spins loosely. An optical limit switch told the computer the actuator is no longer actuating, thus the error message on screen. And the crack affected tooth spacing, which means it would no longer smoothly mesh with an adjacent white gear, and thus explaining the mechanical noise.

The crack propagated through the weakest part of this gear, where a hole has been cut out of almost half of its depth. Why is this hole here? It looks too neat and deliberate to be an air bubble in the casting/molding process, and looks too deep to be any manufacturing process artifact I know about. (Injection molding ejector pin mark, injection sprue cutoff, etc.) I’m curious to its intended purpose, which I’m sure is not weakening the gear to fail under stress. But it is broken now, how might I fix it?

Cyanoacrylate Glue

First attempt was to glue it back together with cyanoacrylate. (CA, “Super Glue”, “Crazy Glue”, etc.) A set of calipers acted as small-scale vise to pinch the gear back together, and a dab of CA was dripped into the mystery hole of weakening. A tiny bit was applied to the back side of the crack as well.

After waiting 15 minutes to let the glue cure, I pushed this gear back on the lead screw.

It popped back open, and the cured blob of CA also popped free. I don’t know what the plastic was used to make this little red gear, but the material is apparently not eager to bind to CA glue.

Melting Plastic

If chemical binding doesn’t work, how about some mechanical binding? I thought I would install the finest tip I have for my soldering iron, and melt the plastic across this crack to weld the gear back together.

Of course, “fine” is a relative term. A 0.5mm soldering tip is pretty fine by normal standards, but in this context it is 1/6 of the diameter across this gear, turning it into a blunt heat applicator.

But I tried my best, mostly successfully avoided ruining the gear mesh surface or inner shaft mating surface. Then I repeated the process for the back side of the gear. After it had cooled, I pushed it back on the shaft.

That didn’t work, either, as the gear opened back up again.

I opened this camera up with low expectation of repair. I thought it was more likely that I would find the point of failure, satisfied with “yep, there it is”, and continue taking this apart into its individual pieces. Now that I have this tiny broken gear in front of me, a repair is tantalizing close and I’m not ready to give up yet. However, leaving the camera and all its components scattered on my workbench would keep me from switching to another project, and many of these components are one big sneeze away from disappearing into nooks and crannies never to be found again. To keep all parts together while I think of things to try, I will reassemble this camera before putting it away.

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. My first candidate didn’t pan out so I went looking around inside the lens assembly to find my second candidate: an actuator moving a lens element.

From right to left in this picture, the members of this cast: a stepper motor only a few millimeters in diameter turns electricity into mechanical motion. A lead screw translating rotational motion into linear motion moving the element up-down. A round metal bar acting as the linear rail for this actuator guiding its path. And finally, a spring that compensates for backlash by pulling the lens nut against one side of the lead screw thread.

Near the left edge of this picture, blurry out of focus at around 8 o’clock, is a bit of yellow FPC (flexible printed circuit) attached to a small optical interrupter sensor. A small plastic tab on the lens element blocks the beam, so the sensor can act as a homing switch for this lens actuator. It would also explain how the camera’s brains knew something was wrong here.

The other side of this mechanism is underneath that shiny metal plate in the top right corner, held by a single screw that is threaded into a metal plate at the base of the tiny stepper motor. (I realized that fact when I loosened the screw and the motor fell out.)

Wow, that is a super thin gearbox. Each of these gears are less than 1mm thick, maybe 0.5 mm?

And here I see clear indication of mechanical failure. The little red gear is press-fit into this end of the lead screw. In this picture, the crack allowed us to see through it to the white gear beyond. The whole gear and shaft it is sticking out above the gearbox in this picture because, with the thin metal plate removed, the backlash compensation spring was free to contract.

I want to get a closer look at the crack, but this is about the limit of my camera with macro lens. Time to try my new digital microscope.

The inexpensive digital microscope sensor is a lot noisier, as if I had turned my Canon sensor up to 12800 ISO. But it had the right lens for more magnification and give me the closer look I sought. Yep, that gear is definitely broken. What might it mean, and what might I do about it?

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.

I have an old Canon PowerShot SD1100 IS compact point-and-shoot digital camera, and I think there’s a mechanical failure keeping it from starting up. All the mechanical bits are in the lens assembly at the core of the camera. As soon as I dug it out of the chassis, my attention was immediately drawn to a motor at the bottom.

I removed four screws that provided most of the holding power for keeping this assembly together, but as I felt around trying to pry it open, I discovered there were a few plastic clips as well. Sadly I realized this after I had already destroyed those clips. Those two clips became the first and second irreversibly destructive thing I did during this teardown. Darn.

But at least I got it open! In this picture, the front (left) and back (right) halves of the assembly are still connected in the middle by several yellow FPC (flexible printed circuit) cables. Since I was here to look for a mechanical failure, my eyes went immediately to the motor and the worm gear attached to its output shaft. I saw irregular surfaces in a lighter shade of gray and thought it indicated failure with black plastic turning gray due to stress. I took a closer look and saw my first impression was wrong. The irregular gray surface was just lubricant, and the worm gear was fine.

At the end of the worm gear is a three-bladed structure that I first thought was a cooling fan, but there was no tilt to the “fan blade” and no air path to the motor. A closer inspection of enclosure front found sensor that would wrap around these “fan blades”. They look like optical interrupter sensors, so it’s not a fan but an encoder disc.

I then visually inspected every gear under my new digital microscope, and found no visible damage to any of the gears. Hmm. I guess the problem isn’t here, and I need to look around for another candidate.

I have an old Canon PowerShot SD1100 IS that makes unusual mechanical noises at power-up, resulting in a failed startup sequence with error message “Lens error, restart camera”. Removing the metal enclosure and LCD screen allowed access to the fasteners holding the lens assembly in place.

Working from the left side, I removed fasteners to free the camera flash assembly.

This is where high voltage boost converters live, feeding into a capacitor (black cylinder) that takes up most of the physical volume of this module. I believe it is also responsible for boosting voltage to drive LCD backlight.

With the camera flash assembly removed, a few gears within the lens assembly are visible through small windows in the enclosure. My hypothesis is that a gearbox was damaged inside the camera, could this be my gearbox?

After removing a few more screws, the motorized lens assembly could be separated from the metal chassis and its corresponding electronics circuitry.

There are two FPC connectors on this assembly. The lower FPC connector is the start of a long and winding set of wires that splits into multiple branches and travel all around this assembly. I traced one set of wires to the motor visible in the lower-left corner, presumably driving the adjacent gears I saw earlier. This tells me the lower FPC connector has all the electrical actuator power signals as well as all wires for sensors that feed back into control algorithms on the main logic board.

Well, all sensors except for the main imaging sensor, which is in the middle of this assembly and has its own FPC connector to send data to the main logic board. The metal plate in the middle is held by three visible Philips head screws. Since I don’t think the sensor is related to my camera startup failure, I’m leaving those alone. In the upper right corner is a fourth screw, securing a separate metal plate for a yet-known purpose I will explore later. Right now I have removed enough screws to pry this apart and look inside for signs of mechanical failure.

My old Canon PowerShot SD1100 IS sat for years and I had thought might be a candidate for exploring CHDK. But something went wrong when I turned it on. Now it makes atypical noises and shows “Lens error, restart camera” after failing its startup sequence.

The bad news here is that camera internals are intricate, so I don’t have great expectations for a successful repair, but I have little to lose by trying. Besides, if there is a mechanical issue, I want to see if I can find the point of failure. The good news is that Canon engineers designed the camera with repair and servicing in mind. There were a few pieces of small double-sided tape here and there, but for the most part the camera is held together by fasteners. Making it far easier to disassemble non-destructively than most modern consumer electronics.

There were six externally-accessible small Philips-head fasteners. Two left, two right, and two on the bottom. Once undone, the front metal face plate can be removed to expose the main logic board and all the yellow FPC (flexible printed circuit) plugged into it.

Four of those six screws also held the rear face plate, which mostly covered the LCD screen. One interesting side note about the screen: it has a wide FPC which wound around the bottom to be plugged into the main logic board consistent with a high-bandwidth connection for low-latency video viewfinder. But there is also a tiny FPC up top with just two visible wires. It plugged into a connector directly behind the camera flash. This is likely for screen backlight. This camera might be old enough for a fluorescent backlight, in which case it made sense to consolidate all voltage boost converters into the same area within the camera.

A few more fasteners became accessible once the front and rear were removed, most of which released black exterior pieces cover top, bottom, and sides of the camera. Then I got stuck. I removed all the screws I could find, but nothing else seemed to come loose.

The key breakthrough was realizing the rear display LCD was held by more than just screws. There were also two metal brackets that were clipped into place by their clever shapes. Once I figured out the physical puzzle of their retention mechanisms, the brackets were freed and I could remove the screen.

Behind the screen is a large number of fasteners in multiple layers. The outermost ring are holding this rear chassis metal plate to other chassis components. Inside that set are screws mounting the black plastic lens assembly to the metal plate. Then screws that hold pieces of the lens assembly together, and the innermost trio held a metal plate that I expect to be part of the main sensor assembly. I’ll work my way from the outside in until I can free the lens assembly.

After reading up on unofficial firmware for Canon cameras, I learned they are (largely) nondestructive with low (though not zero) risk of irreversible damage. Hmm, interesting, it might be worth a look to see what I can and can’t do with such a thing. I went digging into my hardware pile for an old Canon camera, and came up with this PowerShot SD1100 IS. According to Digital Photography Review, this camera was announced in January 2008 so it is old enough to get a driver’s license now. Its 8 megapixel sensor is outdated by modern camera standards, but I expected it is still superior to the OV5640 camera module on board Adafruit Memento. I searched CHDK’s list of supported cameras and it’s on the list. Great!

Unfortunately, I won’t be playing with CHDK on this camera. When I pressed the power button, I expected to hear the familiar sound of a smooth Canon lens deployment. But what I heard instead was a harsh and unfamiliar sound as the lens extended. “Oh, that can’t be good.” I thought. The scary sound quickly stopped and camera display showed an error message: “Lens error, restart camera”. Restarting the camera now has a different sound. Not the traditional smooth sound of lens deployment nor the new horrible grinding sound, but a slight buzz/click that may be a recently-toothless gear turning fruitlessly. What’s clear is the lens mechanism is now stuck in a partially deployed position and power-cycling the camera as instructed does not improve the situation.

The camera has been sitting for at least five years, possibly more than ten years. My hypothesis is some part of the lens deployment mechanism had seized up after sitting unused for that time. And when I turned on the camera, the lens deployment gearbox encountered a lot of resistance. The good news is that it was strong enough to free the seized mechanism, the bad news is the effort to do so damaged itself. Well, I guess now it is a teardown project. I will take it apart and see if I find anything that proves or disproves my hypothesis.