N941WR

N941WR

Legacy Member
A little help for a friend of RV's please.

A buddy of mine has an IO-540 and a D180 and he is having a hard time getting his tach settings correct. He has duel Bendix mags and would like to know how others have set their tach's.

Any help would be greatly appreciated.
 
First, tell them they need to join the Dynon forums - the Dynon folks often answer within minutes, even on the weekends!

Dynon Forums

Second, the answer is in the manual:

"If you are using a p-lead connection, the PULS/REV value will typically be set to ½ or ¼ of the number of cylinders in the engine."

My guess would be 3 (6 pulses in 2 revolutions), but because the mags alternate positive and negative pulses it may be picked up as 1.5 (the Dynon may only sense every other pulse).

Make sure the resistors are in line with the P-lead!
 
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He is on the Dynon forum, I just told him I would post the question here as some of the -10 guys might have the answer.

We have both read the manual and the tach readings are all over the place. He is is trying to find out if he has a wiring or setup issue. And since the setup is easier to change than the wiring, he wants to start there.

You may have hit on the problem with the resistor comment. I'm going out tomorrow to do a tech inspection on his plane and will look for that.

Thanks.
 
Bill,
We've had some issues with the resistors needing to be bigger than the supplied ones when on a 540. We honestly don't know why the 540's are different, but it works.

If he already has the 33K resistors installed, then try moving up to 100K (actual value isn't critical, anything you find at radioshack is fine). Your mention of "all over the place" on the RPM reading is the common problem that is fixed by the bigger resistors. I believe this is covered in our latest install manuals, but earlier ones were missing it.

If the readings are just off by a fixed ratio, but are stable, then that's a software setting of the pulses per revolution.
 
dynonsupport said:
...If the readings are just off by a fixed ratio, but are stable, then that's a software setting of the pulses per revolution.
Click to expand...
Thanks for the info. I'll make sure he reads this.

He had figured out the the pulses per revolution setting but the thing was still jumping around more than it should.

PS. I just got off the phone with Fred, he is ecstatic. He had made note of the resistors but that detail had slipped his mind.
 
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Problem solved. When my friend installed his D180, he read the manual where it said to put in a 33K resistor and if that didn't work, replace it with 100K resistor. Well, being the guy he is, he figured the 100K resistor was a "fix" so he put that in.

After reminding him about the resistor and the comments on this board, he replaced the 100K with a 56K resistor and all is good.

Thanks!
 
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