I've got a Yazaki tach that is dead and I believe that the integrated circuit is the cause of the fault. It is an NEC and says "C1006C" and "8933M" on the top of the chip. I suppose it is a simple timing circuit that feeds a differential voltage output but can't find any references to this chip. Anybody have a clue?

I have 2 good Yaz tachs on hand...if you email me off the brickboard, we could work out a beneficial arrangement.
el Raidman

Thanks, but I bought a spare panel with tach and all else for $10 on EBay. Swapped tachs and the new one works fine. John Sargent had sent me a spare that ran very sluggishly, so I opted for another. I would like to figure out how to fix these buggers, though: to have a shop do it is $175 and a new one is $275.

Do you need another tach? There are more where that one came from.
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john

Nope: I'm set. I'm just curious as to how to repair the broken one I've got and not trash it. But thanks for the offer.