Thread: OM617A Tach Amp
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Old 04-19-2008, 09:37 PM
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pawoSD pawoSD is offline
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Join Date: Oct 2004
Location: Grand Rapids, MI
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Quote:
Originally Posted by techguy512 View Post
It is completely possible for the pickup to fail. Or the cable to fail. Or the solder joints at the sockets to fail. I talked to one person who had the pin at the pulley crash into the pickup and take part of the face off. New pickup fixed it.

The other issue that you might check into is bad wiring between the amp and the gauge. This new amp has the self test feature to help eliminate that as a cause of problems.

Here are the pin assignments to the pickup. The numbers are shown on the socket connector on the fender (after you unscrew the cap).

pin 9 is input from sensor
pin 8 is sensor return (gnd)
pin 7 is sensor cable shield

Get a DVM, and put in resistance (ohms) mode. You should get the following readings:

pin 8-9 80 ohms (+/- 20 ohms)
pin 7-9 infinity (open)
pin 7-8 infinity (open)
I was trying to read ohms on the socket today and couldn't get anything from it (engine was running).....I did every combination of pins (including between 8 and 9) and it just said "0.00"....so I guess I can assume the pickup is dead....where the wire goes into it is kinsa loose and icky looking....I'm betting its damaged (or the cable shielding is) I'll order a new one and try that.....and I might still order one of your amp units soon too. If I can get this thing working I will be a happy man!
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