M800 tach output to drive a Stack ST700 tachometer

[burkey001]

Hi,

Trying to make the tach output of an M800 drive the needle on a Stack ST700 dash display.

I have Aux4 set to tach output, have this wired into Engine Speed on ST700. Have dash configured per engine type and number of cylinders but no love.

Stack manual suggests to connect a 1Kohm pull up resistor from B+ to this tach signal but to check with ECU maker that this wont blow up said ECU.

So that is the question(s),
A) does one need to add a pull up resistor to get the ST700 to work?
B) will doing so hurt the M800?


thanks

andrew

[AdamW]

Andrew,

Yes, a 1K pullup to 12v is fine. A pullup is often needed to drive tachs (especially those designed to be driven from an old points/coil -ve setup), so should fix your problem.

[burkey001]

thanks AdamW, you're a champion. This worked just fine, tach now working