[DeTomaso] Fw: More Problems....

[SOBill at aol.com]

Will,
 
You can verify that the 8920 (if that is what you use) is  working in the car 
using a multimeter.
With the engine running the White wire between the 6AL and the 8920  should 
read around +2.8 V DC. This indicates that the 6AL is providing a 20%  duty 
cycle +12 volt square wave to the 8920. This voltage will not change  with the 
speed of the engine because the signal duty cycle % does not change. If  the 
White wire reads 0 V DC, you may have a bad connection. If The White wire  reads 
+12V DC, the 6AL tach output signal is bad. If the White wire  different than 
+2.8 V DC, something is wrong with the 6AL.
 
With the engine running, the Violet wire tach signal out of the  8920 should 
read as follow:
 
1,000 RPM = 1.27 VAC, 2,000 RPM = 2.62 VAC, 4,000 RPM = 4.75  VAC
 
This indicates that the 8920 is putting out the normal point/coil  type 
signal to trigger the Pantera Tach. Note that we are reading AC voltage  here 
because we want to see the inductive ringing signal which occurs with each  spark 
occurrence. The AC voltage on the Violet wire increases with engine  speed.
 
The 8920 tach adapters are a potted assembly and cannot be  repaired
 
I have an MSD 8920 tach adapter I use for testing tachs when I  repair them. 
I would be glad to loan it to you.
 
Have fun,
 
SOBill  Taylor



SOBill  Taylor
sobill at aol.com



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