Bicycle Mechanics - broken cateye astrale?

So I went on vacation for a week and left my bike at home, everything was working well before I left, returned home and found my bike had been knocked over (crazy cats playing I am sure). The bike feel on the drivetrain side (the computer runs down the non drivetrain side, but the computer is on the drivetrain side of the stem). So I went out and rode the next day and noticed that my computer was not working, i just thought that the detectors had been pushed away (though it was weird that both the wheel and the crank dectectors where not working) but finished my ride and then I played with it. The dectectors looked like they where the correct distance, and I moved them around (closer and further away) still nothing on the computer. I think the battery is fine (the computer is only 12-13 months old) but I dont know for sure, it still has my year's miles on it. I checked the connection from the base to the computer, the wires into the two detectors and into the base (I wiggled them and they seemed fine)
Is there anything else that I can do to check it out? any thoughts?

Do you have a volt-ohmmeter, esp. one with a continuity feature? If so, try this. Put the magnets right next to the sensors. Then put the meter probes to the contacts on the base, two at a time (there are three possible combinations). You should get continuity (beep) on two out of the three.

If you get continutiy on both, then something's wrong with the head. Make sure it's seating exactly right on the base, and that the contacts are actually making contact (yeah, impossible to tell for sure, of course). To know which pair is for which sensor, move one of the magnets away and test again. The one that no longer beeps (duh) is the pair for that sensor. One of the contacts is for the "common" lead.

Once you've done this, you've effectively "mapped out" which pair is for which function, and can then test the head. Take a paper clip or other conductor, and touch the ends to the contacts on the bottom of the head, corresponding with the functions you mapped out above. Touch them momentarily, very briefly, repeatedly, one or two times a second for several seconds. This simulates the sensor completing the circuit when the magnet goes past it momentarily. So it should activate the corresponding function (speed or cadence) on the display.

Actually, you can do this head test even if you don't have any luck with testing the base. You don't need a meter, just something like a paper clip that will act as a conductor. Just do each possible pair as described above, and look for a response on the display.

Back to the base; if you don't get continuity on any of the contacts on the base, then I'd bet it's the common lead that's broken somewhere. Look where it's held to the frame (presumably with zip-ties). Sometimes shock can break the wire where it's pinched. It's a bit of microsurgery, but they can be repaired; I just did it last night (up 'til 2:30AM - ugh) with the wire coming off the cadence sensor on a computer I moved to a new bike (damaging it in the process). On a lot of computers (including, IIRC, the astrale), the wire works like this: the "non-common" lead for each function is the inside "core" lead, with its own insulator. The "common" or "return" lead surrounds it, and is only insulated by the external outside insulation. That makes repairing tricky, in that you can't have even one strand of either lead shorting over to the other. When I did my repair last night, I first slipped a piece of heat-shrink tubing over the wire, out of the way. Then I carefully separated all the strands, twisted and soldered the "core" lead, and electrical-taped it. Then I twisted and soldered the "common" lead, and wrapped the whole thing in a single layer of electrical tape. Finally I slipped the heat shrink tubing over the wound, warmed it up to shrink it in place. I tested it by repeatedly moving a spare magnet toward and away from it, doing a separate test at each step of the process, so I wouldn't get to far and have to undo too much in case it failed at any point.

Oh, and you need a system for hanging your bike (or some such), for the sake of the cats as well as the bike. Before we bought our house (bikes go in the basement, cats DON'T), we kept bikes in the apartment. I had to either hang them up or block them in, or lay them flat somewhere, whenever we left for extended time periods.

Thanks for the advice, should I be looking for a volt spike or an amp spike? I am assuming that I am looking for something never a mA or mV. Actually I think I am measuring volts b/c I will be measuring between two poles, right?

So how do find the break in the wire, if that is what I find it to be.

I have fixed the falling bike problem, my bike is now tied to a book shelf (which is not going anywhere with all my chemistry books on the bottom shelves)

Again, thank you madpogue

Try burnishing the contact points with a mild abrasive such as the eraser on a pencil. Sometimes they become oxidized and do not make a good conneciton.

Thanks for the advice, should I be looking for a volt spike or an amp spike? I am assuming that I am looking for something never a mA or mV. Actually I think I am measuring volts b/c I will be measuring between two poles, right?

So how do find the break in the wire, if that is what I find it to be.

I have fixed the falling bike problem, my bike is now tied to a book shelf (which is not going anywhere with all my chemistry books on the bottom shelves)

Again, thank you madpogue With the head off, there's no voltage going thru the wires. Even with the head, it's probably very low voltage (microvolts). The thing to look for is drop in resistance. Think of those sensors as switches. When the magnet goes by, the switch closes momentarily. You're detecting the close of that switch, so the resistance will drop to near nothing, or, if your meter has a continuity setting, it'll beep. In fact, sometimes you can actually hear the contact "clicking" inside the sensor when you put the magnet up to it. The computer simply counts the number of times the switch closes in a given period of time, does some math, and spews a corresponding number on the display.

As for finding the break in the wire, I've always found it just by seeing/feeling it. You may have to take the whole wiring kit off, and feel for a kink. The most obvious places will be sharp bends and, as I said, where it's pinched to the frame.

I understand now, I will try steveE's idea frist b/c it is easier.
Thank you for all the help