Tech note: Canon printer error B200, B201, B202, B203, B204, B205, B206, B207, easy fix?

It’s no secret that Canon inkjet printers have a couple of cry wolf failure modes that claim to be the end of life for the printer, but are repairable with no parts or special tools. The most common one is the ink disposal error where a software counter expires the silly thing, but it’s resettable… Although Canon would like you to think it isn’t.

Anyway, our trusty Canon MX490 shut down yelling “needs service, B202”. Canon’s official support document says this means it’s dead or at least that you have to replace the cartridges because they “overheated”.

I have been working on inkjet printers since the late 90s and have literally never heard of this failure mode. Furthermore, I’ve never seen a printhead actually do anything close to burning out– at worst sometimes one has had a really stubborn clog, and leaving it lying on a paper towel soaked with distilled water revived it. (Isopropyl alcohol works too but I swear water does it better!)

Radio Shack even used to sell a kit for cleaning the printhead that had a little strip of microfiber brush material and a pen filled with distilled water to wet it with then stroke the head across it. It worked fine but after I figured out a paper towel worked better on certain cartridges I just went low tech.

Anyway, the other part that needs to be clean for correct operation of an inkjet cartridge or printhead module is the electrical connector between the head and the rest of the printer. There’s a matrix of little yellow metal dots or squares on the cartridge, usually on the side that faces the back of the printer. Grab a cotton swab and isopropyl alcohol and clean this, then GENTLY dab clean the matching contacts on the printer carriage, being careful not to snag and bend any parts.

This fixed the printer! No cartridge replacement was needed, I powered it up, it returned the carriage home, did a quick cleaning cycle, and returned happily to service like nothing had ever happened.

Anyway, usually you can access these areas by just sliding the cartridge gently into reach with the printer powered off. Please be warned you may touch ink goopus while doing this. If it’s not possible to move the carriage into reach, you may need to start the printer doing something and yank the power while the head is out of its home position. I don’t know if any Canon machines are like this, but on the old HP Deskjet 600-700 series the cap assembly that seals around the printhead when not in use was raised up by a motor and firmly locked the carriage in the home position. (Sounds like a nice measure to prevent shipping damage!)

On most printers including this MX490, just sliding the cartridge towards the middle uncaps it. If you’re in there, you can also clean the caps and squeegee blades that are near them, this may cure lingering print quality issues like banding or stray ink drops/blobs.

I mentioned specifically cleaning the cartridge contacts with isopropyl alcohol because Hewlett-Packard once had a service note out recommending it – they had a lot of some sort of lubricant (dielectric grease?) that was being factory applied to new cartridges that turned out to be a little too good at maintaining a film between the metal surfaces, causing the cartridges to print poorly or not at all. Their fix was to clean it off. On my printer, it removed visible ink deposits just as well.

If you happen to be here because you’re trying to clean the printhead, please be sure to wipe the squeegee and cap and, if present, clean the two concave grooves adjacent to the printhead with a wet swab. Otherwise you’ll wind up with the head getting re-gooped immediately upon putting it back in, and you don’t want that.

Yes, I need to revise this with pictures, but for now, here’s an unrelated image:

I mean, maybe if you had a lot of droolage from the cyan, magenta, and yellow printhead, it’d look just like this tri-color foaming wax

You know what, just yeet these with extreme prejudice

This WAS a rubber stick on cushion. These are often found as feet on electronic equipment. I actually don’t know why it was ever in there.

It didn’t stop there and ran all the way down the chassis. The first sign of trouble was that I went to pull the scope out of its housing and it just stayed stuck, but then came out with a big SCHLORP sound.

I’ve begun ripping these rubber cushions off my older electronic gear and replacing them with sticky back felt feet if necessary. I wonder if there are silicone rubber equivalents? The silicone rubber keypad on this oscilloscope still works fine despite being made in the early 1990s but that superfluous cushion had to go before. I’m glad I got it before it oozed right out the holes in the back.

As nasty as this would be I’d rather soak in that substance than the contents of the Tesla Dumpster Pool

One bad gloop and she do what I yoinky


Ever seen a TV live truck on scene? Well, if you have, chances are you’ve noticed a thing on top that looks like the top of Crow T. Robot’s head on a tall extendable mast.

What you’re looking at is a foldable microwave dish that can be used to send video from a live shot back to a fixed receiver site that forwards it to the TV studio. At the bottom of it is a remote controlled pair of big chonky motors that let you, standing on the ground, pan or tilt the dish to get it lined up with the receive site so the station can see your live shot coming in.


One of ours got stuck in the up position so I needed to pull it apart and fix it and I intended to take some more pictures of the apparatus as it’s kinda cute – it has two big Bodine gear motors driving worm screw drives via little drive chains, and has limit switch cam assemblies to keep you from going past safe travel limits on the thing.

I found the issue pretty soon after figuring out how to open the weird chassis of the dish motor, which opened vaguely like a milk carton – a hinged milk carton made of sheet metal. I’ve never seen anything quite like that and have to give them points for originality, though, if you had to get in there and the dish was stuck in a position other than straight up, you’d have to disassemble the entire shebang from the sides and take the dish off and everything and eww.

Thankfully, this was stuck straight up, and Tina caught a couple pictures of me working on it after I got it open:

But then the gloop went off.

See, what happened was one of the motor brushes got stuck in the brush holder and wouldn’t advance as it wore down a little, which caused the motor to stop working open circuit. I pulled it apart and managed to get this picture before I realized….. whoops, the armature of the motor and its pressed on bearing were the only thing holding the gloop in. You can see the brush on the right still wedged back in the holder where it can’t actually touch the commutator:

The gloop I refer to is a particularly foul, stinky, sticky, syrupy sort of gear oil, almost all the way up to being a grease in viscosity, but just low enough in viscosity to allow it to make a huge mess in short order. This is the second time I’ve run into it on Bodine motors – there’s no externally visible sign of it having an oil filled gearbox, no fill/drain screw or plug, nothing. You just get a terrible surprise if you dare separate the motor from the gearbox. GLOOOOP.

A fair amount escaped and got all over everything, but there was certainly enough left in the gearbox immersing its guts that I don’t feel I need to disassemble the whole thing and try to refill it. Nah, it’s just a learning experience… AGAIN…. BEWARE THE GLOOP.

Otherwise it will get the song stuck in your head. That song never leaves…. not that it ever has to.

There’s an extended version too