wrote in message
...

Sam,

Yes, you might be correct about that. I have finally made a contact
with someone in Germany about this problem and I'm awaiting their
response. The device is sealed (for rough outdoor use) and I suspect
the circuits are epoxyed inside, although I should break one open at
some point.

The parallel connection idea is still an option, at least to keep
further costs down.



I originally thought this was referring to an IC, not a sealed circuit. It's
quite common for a manufacture to use a standard casing for a device and
simply not internally connect pins that are not needed. As Sam said, it's
entirely possible that this is only a 3 channel tach, and that 4 channel was
a different model in the same box.