"pimpom" wrote in message ...
DaveC wrote:
I'm trying to troubleshoot an error with an HP ink jet printer
(Photosmart 3210) that says "Ink System Failure". All other
components seem functional.

In the printer there is a small PCB with a few soldered components
that appear to sense ink flow or pressure. It is in series with the
pump output.

http://i48.tinypic.com/o8xz84.jpg

http://i49.tinypic.com/r76kib.jpg

How does this work? Are these 6 LEDs and photodiodes? Just detecting
the presence of ink doesn't seem likely. Wouldn't movement or
pressure be what is detected?

What does this PCB do and how does it do it?

Thanks.

If you're talking about the tiny black rectangular parts numbered R1-R6, they are resistors.

I had a HP inkjet fax with several hundred MB of driver bloatware.
It refused to print B/W fax and complained colour cartridge was empty.
It has a separate B/W cartridge that was full. Sounds like their firmware
and software was written by sales people.

M