What does it mean for a Canon printhead to be bad

[micky]

What does it mean for a Canon printhead to be bad, for example on an
MP-730 All in one.

(I know this is a lot of time to spend on a printer that can be
replaced for say, $100, but I get a lot of satisfaction from fixing
things, and quite a bit of satisfaction from trying to even when I
fail.)

The error message is "wrong cartridge", but everyone on the web and
the Canon manual itself says the problem is the printhead.

What can be wrong with a printhead?

Is it electrical? One of the webistes selling new ones
talked about burned-our resistoirs, but I tested with an ohmmeter and
every contact point on the printhead had continuity with another
contrac point. The resistance was usually 40 kohms to 120 kohms, bur
for a one or two it was almost 200K, and for one or two it wa under
1000, maybe under 100.

There are about 44 contacts on the printhead, 4 rows of 9 and one row
of 8. But there is one contact fewer on each row of pins in the
printer carriage. So that's 39 contacts altoghether.

Is it clogged? The owners manaual didn't say anything about
cleaning it, but somet of the webpages that discuss the error message
talk about cleaning. I soaked it in unbranded Prinhead Cleaner**,
and it seems pretty liquid inside, but maybe there is still a clogged
spot, but how would the printer know that to give an error message?

**It didn't smell like isopropy alcohol and didn't smell like Windex,
but it didn't say what it was.

Is there a third thing that could be wrong with it?

Thanks.

 

[micky]

BTW, the ink cartidges on this printer have no electrical connectors.
Just ink, and everything else is in the printhead afaik.

 

[micky]

Each nozzle that produces a blob of ink on the paper are miniature
electric kettles.... about the easiest way I can describe.
'
Here's a link'
(http://mimech.com/printers/inkjet-printer-technology.asp) that will
help you know the difference between Inkjet and Bubblejet printers.

Wow. Until this very moment, I had no idea Inkjet and Bubblejet were
different at all. I figured they were different brands' names for
the same thing, like Hydramatic drive and Torqueflight might be.

This is a real eye-opener.

Simply an inkjet printer, Epson, HP for example squirts the ink via
oscillating plates a bubble jet actually boils the ink such as a Canon
bubble jet for example.

Bubble jet heads do wear out, the ol' heating element just 'pop's it's
clogs' like a electric kettle element... usually when in want of a brew!
The only thing is to be sure it's not a clogged nozzle which can usually
be cured, but if a nozzle or two is burned out it's a replacement head
as nothing can be done with it.

I can certainly see that, but shouldn't Canon let it print anyhow, do
a bad job since a couple nozzles are burned out, but at least allow
the user to print something until he has time to buy a replacement
head or a new printer. Only the poorest shmoes won't do one or the
other, and everyone will be a lot happier with Canon.

Sometimes the contacts can get tarnished on heads that are replaceable
such as the Pixma IP4000, 5000 for example... this is simply cured by
removing the head and wiping the gold contacts on the head and on the
head holder with a dampened cloth with say Isopropanol or similar
stuff.

They looked fairly clean in the first place, but I have cleaned both
the contacts and the pins twice with isopropanol. I used to clean
TV tuner contracts, turret and wafer, with turner cleaner, and I could
be sure I was doing a good job because I could see the turret
contracts get shiny, and because channels that didn't come in started
coming in better or perfectly. Did that 20 or 30 or 40 times, so I
must know what I"m doing. Used tuner cleaner, but that has
lubricant. No need to use that here, since the lever/latch keeps
things from moving.

Any chance the ribbon cable that goes into the carriage has wiggled
loose, at one end or the other? I never touched it, but maybe the
previous owner did.

There were at least 4 or 5 previous owners, at one time. I got this
for my ex-girlfriend, from Freecycle. It came from a lawyer's office
and the lawyer who gave it to me said it worked. But maybe he thought
that because they put it in the closet instead of throwing it away.
there are 2 or 3 lawyers and a secretary or two and maybe it broke
when he was out of the office, and he didn't know. Or maybe he
forgot. They had bought a fancier one with an output sorter or
something. He thought it shouldn't sit in the closet when someone
could use it. He seemed like a very nice guy.

Thanks.