Can optic board be checked without a encoder or mouse hack ?

[Mamezilla]

I am wondering if optic boards can be tested or checked without plugging them into a mouse hack or an encoder (with a multimeter for example).  I tried to do a mouse hack yesterday with a cheap PS/2 mouse I got at the local Wal-Mart, but while doing so I fried the PS/2 port on my second computer I use in my workshop.   BTW, this is the trackball that has different optic boads I was reffering to in my post a few days ago.  Before I try something else, I want to make sure that they indeed work, since I don't want to fry another PS/2 port.

Thanks.

Guy

[OSCAR]

As luck would have it, I already have a cut-n-paste email because I get this question a lot!  Below is my typical reply to this question:


There are a couple quick measurements you can take with a multimeter to check your optic board.   First connect +5V and GND to the board.  Then put the black lead from the multimeter on the optic board GND pin (or the back of the board where the solder pad is if it is easier), and the red lead on the X1 pin.  The reading should be about .5V.  Next take a reading on the X2 pin, you should get about .5V there, too.

Then you can slip a piece of paper or other opaque material in the slot between the optics to block them.  Your readings from GND to X1 & X2 should be around 4.5V, respectively.  If you don't get these readings, one of the phototransistors may be shorted or there could possibly be a bad solder joint on the optic board.

The readings could be reversed (getting 4.5V where I said you would get .5V) depending on the optic board and the type of phototransistors used on the board.  As long as you are getting the two different voltages with "open" and "closed" optics, you are fine.