Re: scavenging opto-isolators

In article <y93hcj4f8jz.fsf@xxxxxxxxxxxxxxxxxxxx>,
Allan Adler <ara@xxxxxxxxxxxxxxxxxxxx> wrote:

Allan Adler <ara@xxxxxxxxxxxxxxxxxxxx> writes:

I photocopied the printed circuit with a copy ratio of 4:1, and found it
wasn't very legible. I'll try to borrow a digital camera and take a picture
of the circuit. That might give me better enlargement and more control over
the quality of the picture. Meanwhile, I'm going to sit down with the PCB
and try to take a careful inventory of the components on it. I don't have
access to a multimeter at the moment so I can't conveniently determine which
components are connected to which, but maybe I can eyeball it with a
magnifying glass.

I've made a little progress, which also raises a few questions. One side
of the board has the printed circuit layout and the other has the big
components. The layout side has the following markings on it for components:
C2,C3,C4,C6,C8,C9,C10,C11,C12
R2,R3,R4
DZ1,DZ2
JP1, JP2, JP3, JP6, JP7

The component side has the following markings on it:
C1
R1
S1, S2, S3
U1, U2, U3, U4
JP6, JP7
CN1

Taken together, that gives:
C[1-12] - {C5,C7}
R[1-4]
DZ[1-2]
JP[1-7] - {JP4, JP5} with JP6,JP7 each occurring twice and maybe one of each
of the redundant JP6,JP7 supposed to be JP4,JP5 resp.
S[1-3]
U[1-4]
CN[1]

The letters seem to mnemonics or abbreviations. C for capacitor, R for
resistor, DZ for zener diode (?), JP for jumper, S for switch, CN for
connector, U for unusual component.

These are all standard layout and parts-list abbreviations. As you note,
R = resistor, C = capacitor, etc. however, U = "Integrated circuit".
There are also others, such as "Q" for transistors, or L for coil, but I
don't expect you'll see that on a mouse board. Possible, but I don't
expect it.



There are components on the layout side but they are very flat. One of the
DZ's looks like it might really be a diode. The resistors, capacitors and
jumpers on the layout side all look like black boxes of some kind, but
the jumpers have a O written on them, the resistors have numbers such
as 513 and 330 written on them (actually, they are block lettering and
upside down might spell some acronym like DEE or EIS) and the capacitors
have nothing written on them. Could these weird components be surface
mount technology? They are visibly and abundantly soldered.

Yes, these are surface mount components. The "513" and "330" notations
you mention are two values of resistor. The "0" you noticed for jumper
is because a 0 ohm resistor IS a jumper. (or, thinking the other way, a
jumper is the same thing as a 0-ohm resistor) Black bodies with solder
on ends are almost always resistors. Tan/reddish bodies with solder on
the ends are almost always capacitors, though they might be diodes.
Black bodies with more than two connections (two on one side, one on the
other, for instance) are transistors (and will be labeled "Q#" on the
board) while integrated circuits will have anywhere from 4 to 50 or more
individual connections to the board.


The switches for the left and right buttons look a little like car batteries
and have written on the side

1A 125V AC
C NO NC

and each of C, NO, NC is above one of 3 leads going into the board.

When referring to pin function on a switch, C = common. NO = normally
open. NC = normally closed or no connection.

It appears
that the C and the NC are connected by the layout.

Not uncommon. Basically, pushing the button hits the switch, which
connects the "NO" pin to the "C" pin. The "NC" pin is irrelevant

The third pushbutton
switch looks more like a cubical building and is unmarked. The track wheel
has one end of its axis resting on that third switch but the other end of
the axis goes into something with a hole in the middle and which is apparently
turned by the rotation of the track wheel. Maybe it is a tiny generator? It
has three leads going into the board.

That will be the rotary encoder for the wheel. Probably another opto
device, but may be something else. It's NOT a generator, though...

The labels are much bigger than the connections in the layout and it is
hard to be sure what refers to what. Also, I'm not sure what is connected
to what yet. The fewer components remain unidentified, the easier it will
be to guess the role of the others.

Since mice are abundant, one solution is to remove the components and
test them. I don't have any test equipment of any kind at the moment, but
it would be a reason to acquire some.

--
Don Bruder - dakidd@xxxxxxxxx - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info
.

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