It all started with a vague error code (shown in the image above) on [nophead]’s Bosch SMS88TW01G/01 dishwasher, and it touched off a months-long repair nightmare that even involved a logic analyzer. [nophead] is normally able to handily diagnose and repair electronic appliances, but this time he had no idea what he was in for.
Not only were three separate and unrelated faults at play (one of them misrepresented as a communications error that caused a lot of head-scratching) but to top it all off, the machine is just not very repair-friendly. The Bosch device utilized components which are not easily accessible. In the end [nophead] prevailed, but it truly was a nightmare repair of the highest order. So what went wrong?
One error appears to have been due to a manufacturing problem. While reverse-engineering the electronics in the appliance, [nophead] noticed a surface-mounted transistor that looked crooked. It was loose to the touch and fell into pieces when he attempted to desolder it. This part was responsible for switching an optical sensor, so that was one problem solved.
Another issue was a “communications error”. This actually came down to ground leakage due to a corroded and faulty heater, and to say that it was a pain to access is an understatement. Accessing this part requires the machine to be turned upside down, because the only way to get to it is by removing the base of the dishwasher, which itself requires a bizarre series of awkward and unintuitive steps to remove. Oh, and prior to turning the machine upside down, one has to purge the sump pump, which required a 3D-printed adapter… and the list goes on.
And the E02 error code, the thing that started it all? This was solved early in troubleshooting by changing a resistor value by a tiny amount. [nophead] is perfectly aware that this fix makes no sense, but perhaps it was in fact related to the ground leakage problem caused by the corroded heater. It may return to haunt the future, but in the meantime, the machine seems happy.
Has it really come to this? Are we really at the point that dishwashers have proprietary detergent cartridges that you’re locked into buying at inflated prices?
Apparently so, at least for some species of the common kitchen appliance. The particular unit in question goes by the friendly name of Bob, and is a compact, countertop unit that’s aimed at the very small kitchen market. [dekuNukem] picked one of these units up recently, and was appalled to learn that new detergent cartridges would cost an arm and a leg. So naturally, he hacked the detergent cartridges. A small PCB with an edge connector and a 256-byte EEPROM sprouts from each Bob cartridge; a little reverse engineering revealed the right bits to twiddle to reset the cartridge to its full 30-wash count, leading to a dongle to attach to the cartridge when it’s time for a reset and a refill.
With the electronics figured out, [dekuNukem] worked on the detergent refill. This seems like it was the more difficult part, aided though it was by some fairly detailed specs on the cartridge contents. A little math revealed the right concentrations to shoot for, and the ingredients in the OEM cartridges were easily — and cheaply — sourced from commercial dishwashing detergents. The cartridges can be refilled with a properly diluted solution using a syringe; the result is that each wash costs 1/75-th of what it would if he stuck with OEM cartridges.
For as much as we despise the “give away the printer, charge for the ink” model, Bob’s scheme somehow seems even worse. We’ve seen this technique used to lock people into everything from refrigerator water filters to cat litter, so we really like the way [dekuNukem] figured everything out here, and that he saw fit to share his solution.
The build consists of a whole heap of hardware all lumped in a sizeable plastic tub. A washing machine solenoid lets water into the system, and it’s heated by an element in the base of the tub. It’s then pumped through a garden sprinkler head to give the dishes a good all-over spraying. At the end of a wash cycle, the drain pump then dumps the water to let everything dry off. An ESP8266 and a bank of relays are in place to run the show, with the user selecting wash programs via buttons and a small screen.
Dishwashers are great at washing dishes and even rinsing them, most of the time. Where they tend to fail is in the drying part. Somehow these things dry hot enough to warp stoneware dishes, but not so well that things are actually dry when you open the door. Blame it on the lack of air movement.
[Ivan Stepaniuk] is listening for the dishwasher’s frequencies with a microphone, amplifying them with a trusty LM386, and using an STM32 blue pill to crunch the audio. [Ivan] has plans to incorporate an ESP8266 board for IoT, presumably to get a notification when the door has been opened successfully. Check out the demo after the break.
There’s a story that goes back to the 1980s or so about an engineering professor who laid down a challenge to the students of his automation class: design a robot to perform the most mundane of household tasks — washing the dishes. The students divided up into groups, batted ideas around, and presented their designs. Every group came up with something impressive, all variations on a theme with cameras and sensors and articulated arms to move the plates around. The professor watched the presentations respectfully, and when they were done he got up and said, “Nice work. But didn’t any of you idiots realize you can buy a robot that does dishes for $300 from any Sears in the country?”
The story may be apocryphal, but it’s certainly plausible, and it’s definitely instructive. The cultural impression of robotics as a field has a lot of ballast on it, thanks to decades of training that leads us to believe that robots will always be at least partially anthropomorphic. At first it was science fiction giving us Robbie the Robot and C3PO; now that we’re living in the future, Boston Dynamics and the like are doing their best to give us an updated view of what robots must be.
But all this training to expect bots built in the image of humans or animals only covers a narrow range of use cases, and leaves behind the hundreds or thousands of other applications that could prove just as interesting. One use case that appears to be coming to market hearkens back to that professor’s dishwashing throwdown, and if manufacturers have their way, robotic dishwashers might well be a thing in the near future.
No matter how mad your 3D printing skills may be, there comes a time when it makes more sense to order a replacement part than print it. For [billchurch], that time was the five-hour window he had to order an OEM part online and have it delivered within two days. The race was on — would he be able to model and print a replacement latch for his dishwasher’s detergent dispenser, or would suffer the ignominy of having to plunk down $30 for a tiny but complicated part?
As you can probably guess, [bill] managed to beat the clock. But getting there wasn’t easy, at least judging by the full write-up on his blog. The culprit responsible for the detergent problem was a small plastic lever whose pivot had worn out. Using a caliper for accurate measurements, [bill] was able to create a model in Fusion 360 in just about two hours. There was no time to fuss with fillets and chamfers; this was a rush job, after all. Still, even adding in the 20 minutes print time in PETG, there was plenty of time to spare. The new part was a tight fit but it seemed to work well on the bench, and a test load of dishes proved a success. Will it last? Maybe not. But when you can print one again in 20 minutes, does it really matter?
Have you got an epic repair that was made possible by 3D printing? We want to know about it. And if you enter it into our Repairs You Can Print Contest, you can actually win some cool prizes to boot. We’ve got multiple categories and not that many entries yet, so your chances are good.
As if Windows Update wasn’t bad enough, one has to deal with a plethora of attention-hungry programs and utilities all begging for a continual stream of patches from the Internet. It’s exhausting, but unfortunately also par for the course. Many of these updates are to close security vulnerabilities that could otherwise expose your computer to undesirables. The Internet of Things will only expand the amount of hardware and software you need to keep updated and protected on a daily basis. Now, it’s your dishwasher that’s under attack.
The Register reports that Jens Regel discovered the bug in a Miele dishwasher with a webserver. It’s a basic directory traversal attack that can net the intruder the shadow password file. Armed with this, it’s simple to take over the embedded Linux system and wreak havoc on your local network.
It’s not particularly surprising – we’ve talked about IoT security and its pitfalls before. The problem is, a dishwasher is not a computer. Unlike Microsoft, or Google, or even the people behind VLC, Miele don’t have infrastructure in place to push out an update to dishwashers worldwide. This means that as it stands, your only real solutions are to either disconnect the dishwasher from your network, or lock it behind a highly restrictive firewall. Both are likely to impede functionality. Of course, as always, many will ask why a dishwasher needs to be connected to the Internet at all. Why indeed.