Hi..
We bought the motor with encoder like that:
But we not able to see which wires are 5V, GND, sensor A and Sensor B for the encoder. Is there anybody here that know this motor?
Hi,
looking at pictures on sites selling this motor and encoder, the encoder opto devices have part numbers on them.
This should give you some help with reverse engineering a circuit diagram as it is only two opto-interrupters and some PCB tracks.
If you can give us a good clear set of close up macro pictures of the small PCB and the optos we might be able to help.
It seems everybody want to sell them, new or second hand but no one wants to provide any data.
Tom.... 
Hi
I got same issue but with a HP scanner motor.
I used a multimeter to get the pin-out in diode mode. Soon I got the emitter pins ( was the easy one, as a diode, with multimeter you can find the anode and cathode pin), I was able to get the encoder pins. A and B.
Some one managed with code,:
http://forum.arduino.cc/index.php?topic=156312.0
As a quadrature encoder try here to:
Yes, you can probably work it out this way, the PCB traces are accessible and
the opto interrupter probably consists of a dual emitter and dual detector, so
the wiring ought to give the game away.
There are other, better, images of that part number findable via Google, BTW
If the pics not clear I will take a picture again with another camera..
I tried to follow after the line but it didn't work yet.
Hi
It's for sure a 2x encoder optical, to create a quadrature encoder, as MarkT suspected.
Now the pin out:
I'm pretty sure ( not 100% positive ) pin 5,6,7,8 are the emitter, 2 led are connected in series. Pin 6,7 are GND and 5v, can't say witch one is. ( test with multimeter)
Pin 6 is common with the detector, In my HP was the +5v.
My concern is the detector, pin 1-4, and pin 4, can't see the line on PCB.
So with multimeter in diode mode, you can detect the anode and cathode of the emitter.
For the detector... cant say much more.
Hi
I know, long time, but try here:
I found arssants link before I got here but I am still not sure I'm doing it right.
I've read that you need resistors in combination with encoders and according this data sheet, which I think applies here, they have a 10K resistor between Vcc and the channels but I don't know if it's on the board or if I have to put it there myself.
The best output so far seems to be 0V or 0.2V when I rotate the shaft.
I am connecting it according to: 
Am I supposed to put resistors externally on both the emitter Vcc pin and pulse out pin?
http://bobodyne.com/web-docs/robots/Trippy/MicroMoEcoder.pdf
You may get by just using "pinMode(x,INPUT_PULLUP)" in Setup(), if that's not enough pullup you'll need a 10k R from 5V to each channel pin (A & B).
I use this kind of quad encoder that I salvaged from HP/Canon printer-scanners. Some of them have pull up resistor build in for both channel ( receiver ), and even resistor current limiter for emitter, so they are ready to use with arduino without major mod. When not, I use 10k resistor pull up and current resistor limiter for the emitter as you can see on pic at post #5.