Re: hp officejet 4110 all-in-one

Michael Black wrote:

Based on people's questions about making use of scrapped electronics,
a common mistake is to strip it down without taking notice. So
they end up with components that have no information, or they save
some key parts but neglect to save the associated parts that may
also be difficult to get.

Often, one can extract information from the complete unit, and once you've
taken it down to individual parts that information is lost.

So you find a radio, and you can start making guesses about the ICs even
if you can't find part numbers, because you have the whole thing in front of
you and have a general idea what sorts of ICs are needed. Unsolder those
ICs from the board, and they are just ICs with no recognizeable part number.
On the board, you can trace the circuitry to get an idea of what the pins
do, or to verify whether a guess at what the IC might be (under a house
number) matches a common IC. Even things like what pins are grounded and
what pins get power can pretty much immediately sort out IC guesses; if
there's no match to the guessed IC, then you need to guess again. Each
iteration brings new information.

You look for the same sort of function in a databook, and then see if
they match the unknown IC. A differing number of pins immediately rules
out the guess, the wrong ground pin eliminates others. But then you
trace the circuit board following the guessed IC's external connections,
and you may find a match. Often that can be easier, imposing a known
circuit, on a circuit board circuit, than tracing out everythying
first and then trying to make sense of it.

Or, a common item in radios are ceramic filters, which can be useful
if building radios. But once those filters are desoldered, you've lost
what the terminating resistors are, and which pin goes to ground, and
how the inputs are connected to the driving source, and what's connected
to the output pin.

Or sometimes you have small boards that could be used as is, so long as you
know how to connect them. So the IR receiver in a VCR is actually on
a small board, or you can hack out the area with a hacksaw. Take note
of what is ground, and what is the power supply line, and then that
third line must be the data output. You don't even have to know
what's inside the module, because you can treat it as a black box.
Desolder the parts, and you have an IC that you have to find data
for, and then you have to find out how to wire it together, and get
the parts, which is what you started with originally.

Find things with exotic parts, that you know are valuable or you
are especially interested in, and if you aren't going to use them
right away, it makes sense to keep the boards or equpment intact to some
extent. Because when the time comes when you need that exotic part, you
will be glad to have the information you can extract from tracing the
circuit, and in some cases glad to have the connected parts.

At the very least, marking parts that can't immediately be identified
with whatever information you can gather form the board (and even
where you got it, since you might want to look for similar equipment,
or you might get lucky later and find a schematic that explains the parts.

A few years ago, I needed a 24V power supply to run something, and for
some reason I remembered that I'd seen indications of higher voltages
in printers. So I grabbed one of the injket printers that I'd brought
home, and it offered up a switching supply of the needed voltage. I
wish I'd recorded the brand and model, because it would be handy to
find some more of the same type, rather than randomly bringing them
home or taking them apart on the sidewalk until I found a match.

For that matter, I know I've taken other inkjet printers apart
where the power supply was a separate board, kept them intact because
I am far more likely to make use of a power supply than to build
one up from parts lying around.

Michael


That is what Sharpies are for: Write the brand and model on
subassemblies as you junk damaged equipment.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
.

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