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Looking for Penny & Giles / Traxsys trackball help please
lilshawn:
the chip is performing a preliminary cleaning of the rotation signal from the x and y sensors and transforming it to a straight digital signal... a kind of digital signal conditioning if you will.
you will just need to follow or "buzz out" with a continuity meter... the signal from the X receivers to the chip. the output side of the chip is going to be the x direction. once youve found where the signal goes in, it's easy enough to look on the datasheet to find out where it comes out. then buzz the output pin of the chip and find the appropriate pin in the connector.
hsr:
Thank you again.
Yes, looking at the data sheet, I can see which in is related to which out. At least I think it makes sense.
Which leg of the signal receiver should I be trying to trace? There are three. On the mouse hack I did many, many years ago, I used the outer two of the three as the signal+ and signal- from the sensor board (they were replacements bought on BYOAC in this thread for a spinner).
lilshawn:
one of the legs is going to be a power feed, then the other 2 are going to be the signal (the slots on the encoder wheel are cut in such a way in that one of the signals gets turned on slight before the other.) it's basically a transistor. It just uses light to turn on the transistor instead of a 2nd voltage.
you would hook one to xa and the other xb and then ya and yb. ground and 5 volts come from the board to power everything. when you move the trackball the signal oscillates from xa to xb over and over. this gets translated to movement.
that said, you will not want to take signals from those test/solder pads. you need the chip to do it's magic to the raw signal. find where the x signal goes into the chip and then comes out. it should be easy enough to find what pin in the connector it is. once you've figured that all out you can hook it up and test it. if you end up with a mouse cursor that is opposite (up goes down) then just reverse the a/b signal wires and it'll go the correct direction.
hsr:
Ok, the power feed was obvious.
The other two leads of both X and Y are both connected to pins 1 and 7 on the IC.
The X direction at 1.6k ohm at pin 1 and again both to the number 7 pin on the IC which is the vdc- at 1.6k ohm also.
The X direction at 4.7k ohm at pin 1 and again both to the number 7 pin on the IC which is the vdc- at 4.7k ohm also.
I'm lost (again)...
Pin 1's output is pin 2.
ark_ader:
I have one of those (I took off the plastic shield) nice trackball but those buttons get in the way...
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