My Self-Cleaning Litter Box Saga
Cats are very independent creatures, which makes them well-suited to living with me. I tend to be gone for days (or even weeks) at a time, and in order to assure their needs are met while I'm out, I've taken advantage of a few pieces of handy home automation.
I tried two other brands of self-cleaning boxes over the last four years, and was extremely disappointed with both. Not only did they not work tremendously well, but one (whose name I won't mention, but they're one of the better-selling brands) lasted only a number of weeks before a particularly large clump jammed the mechanism and stripped a couple of *plastic* gears. Come on, plastic gears on something with a fairly high-torque motor? That's just crappy cheap engineering. The other died due to failed electronics - it would appear that one of my cats demonstrated some unique aiming skills, and when that was combined with poor board placement, led to the destruction of one of the drive FETs. My guess is that the sudden wetness of the board may have caused one of the gates to be permanently on, leading to a direct short through one side of the H-bridge. Regardless, it was a smelly, corroded, non-functional mess by the time I took it apart, and I deemed it a loss.
Life with the ScoopFree
After my frustration with the stripped gears and blown electronics marking the end of some rather pricey purchases well before I felt I'd gotten my money's worth out of them, I was almost ready to go back to a regular litter box. However, some reading online revealed a less-known brand - the ScoopFreeTM, made by Lucky Litter, LLC. Several folks had mentioned that it was much more ruggedly built, and as an added plus, it used the silica crystal litter that I was particularly fond of, rather than the nasty, clumpy, smelly clay crap. So, I decided to give it one more shot, and went on down to Petsmart to purchase one.,
After several years of ownership now, I can definitely say that my ScoopFreeTM has more than paid for itself in saved efforts. Unlike certain other brands that I won't discuss here, it uses a long metal leadscrew on each side, synchronously driven by a toothed belt. Yes, the worm gear and belt drive gear are both some sort of plastic, but unlike in the other failed catbox design, the belt should start slipping long before any damage occurs to the gears.
Also, from an electronics standpoint, the board is placed high above any spot where nature's nastiest, most corrosive substance - cat urine - could possibly get to it. Likewise, motor, limit switches, etc. are all adequately protected. About the only thing that isn't is the IR led/sensor pair that detect when a cat is in the box. This is usually not a problem, but read on - yours may need to be cleaned.
Lest I sound like a corporate shill, I'm not. I have no connection to these folks at all, except to say I really like their product. Hopefully I can help convince other folks that this product really does do what it says, and is well-built enough to not be a waste of money. It's an excellent way of assuring your cat a clean place to go, even when you can't be there to clean it for them.
How to Fix the Blinky Box
Obviously if your box is in warranty and something goes wrong, you should try getting warranty service before opening it up - unless you're like me and can't resist the urge to take things apart and fix them yourself. Be aware that opening it will almost certainly void your warranty. So, if you do this, I take no responsibility for it... I present this only as my hopefully helpful experiences, so those of you in a similar situation might fix it yourself.
My only problem happened about 18 months after buying it, during the summer of 2007. Suddenly, the box wasn't sensing cats, and wasn't cycling. It just sat there, with the green LED blinking away at a reasonably quick pace. The manual said that moderate flashing indicated a cat was in the box, and a rapid flash indicated a jammed rake. A quick check showed no cat in the box (unless one of my three monster tomcats had suddenly become invisible...), and the rake safely seated at the home position. What was going on?
I took the box apart (remove the power cord, turn it over, and take out the screws on the bottom) and started probing around with a meter, as I assumed the problem was with the limit switches not correctly sensing rake position. A few quick checks proved me wrong on that. As I started testing further, I realized that the phototransistor responsible for sensing cats was not working correctly. Closer examination showed that it had apparently been "moistened" by one of its regular users, and had become covered with gunk. So, the fix is as simple as removing the two optical boards (the IR led on one side and the phototransistor on the other) and cleaning them. I personally use paper towels soaked in water with a bit of bleach, but use whatever you want. Just be careful not to get too much liquid on the board, the traces, or the connections. You just really need to clean the front of the lens.
As a final thought, once you have the box disassembled, you might want to consider putting some white lithium grease on each leadscrew. I've found from experience that this makes the box work better as it ages. I found that over time, the motor sounded like it was working harder, and the rake was moving slower. Disassembly found some corrosion on one of the leadscrews. So, grease 'em up (just a little) to ease the load on the motor (should improve service lifespan) and help prevent corrosion.
Nevermind the Details, We Want Pictures!
Okay, you asked for it - here's what's inside that box: ScoopFree disassembled for cleaning