it would be a good idea to verify that 5v/ground/data lines are on the same contacts before applying power.
Hope you didn't fry anything.
I thought they were identical, they look the same except the circuit board (go figure).
Grab your multi-meter and cell-phone/digital camera. It's time to reverse-engineer the optical board.
There are two pairs of optical circuits like this simplified diagram.
- Two IR LED circuits (left) with two connections each. (5v and ground)
- Two photodiode circuits (right) with three connections each. (5v, ground, and encoder)
First thing to find are the two IR LEDs.
You may need to pull the encoder wheel so you can see the IR from a lower viewing angle like this when you check the LEDs.
Based on this picture, looks like the LEDs are between the screw heads.
- If I had to guess which edge connector contact is which based only on the board layout, I'd guess, from left to right in this pic: ground (or 5v), no connection, data line, data line, 5v (or ground), no connection.
Set your multimeter to diode check and clip one meter lead to the bottom lead of one of the brown-body resistors and the other meter lead to the right lead on the lower horizontal tan-body component. (resistor or diode?)
- If you get the correct polarity, LED check mode will
dimly light the IR LED.
-- You will probably need to use your cell phone camera to see the LED since IR is outside human eye visible wavelengths, but is within the visible wavelengths of the camera.
- If the LED is lit, check the other LED.
-- If one LED is good and the other is burned out, the cursor will move back and forth one step when you turn the wheel -- you'll need to replace the optos.
- If the LED isn't lit, swap the red and black meter lead connections (polarity) and check again.
Once you confirm the connections that light the LED:
- Trace from the red lead connection through components to the edge connector -- that's 5v.
- Trace from the black lead connection through components to the edge connector -- that's ground.
If neither polarity connection works, either the LEDs are under the encoder wheel
or you fried both LEDs and need to replace the optos.
Once you've got the 5v and ground connections sorted, that just leaves the two data lines.
- If you get those backward, the wheel will move the cursor in the opposite direction expected.
Scott