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Tach installation on 15hp

T

tomf

Regular Contributor
"Hi all,

bear with me if t

"Hi all,

bear with me if this is obvious or has been already discussed to death in the forum archives, but is it possible to hook up a normal marine tach to a '93 manual start 2-stroke Merc 15hp?

I've been running a Tiny-Tach which works great for the RPM reading - except it wreaks major havoc on my fish finder / depth sounder. I've tried to vary the wire routing, but to no effect. So at the moment, I'm basically faced with an either/or choice between tach and sounder.
sad.gif


The problem seems to be the Tiny-Tach sensor wire around the HT lead acting as a mini radio transmitter. So my question is, could I install a normal dial tach and use my charging rectifier for the tach signal? I'm running the unregulated 5 amp stator+rectifier charging system connected directly to the battery, but there is no dedicated tach output there, just the 2 leads from the rectifier.

Thx again..!"
 
If you in fact have a charging

If you in fact have a charging system you can. The send pole on the tach would connect to either of the 2 yellow wires going to the rectifier. Make sure the tach can be set to 5P.
 
One more thing you can try: W

One more thing you can try: Wrap the Tiny Tach cable with aluminum foil tape. That isolates it pretty well and might eliminate your problem.

Jeff
 
"Hmm, good idea, could try tha

"Hmm, good idea, could try that. Do you wrap the entire cable up to the display unit or just around the sensor wire wrappings?"
 
Success! Some kitchen foil and

Success! Some kitchen foil and aluminum tape around the exposed part of the sensor wire did the trick. Thanks for the tip.
 
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