Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Unstable UMA Tach

Matronics Email Lists Forum Index -> Zenith-List

View previous topic :: View next topic

Author Message

rdewees(at)mindspring.com
Guest

Posted: Fri Mar 10, 2006 6:32 pm Post subject: Unstable UMA Tach

While on the subject of unstable tachs I have a question myself.  I have 

a UMA tach on my Jab 3300   (0 to 3500 rpm scale) and it's spot-on 

accurate from 1000 rpm to beyond 3100 rpm. The problem is that it just 

stops reading and goes to zero rpms below 950 or so rpms. When it's 

sitting on O rpm I don't know if it's at low idle or stopped.  Don't 

want to grind up a starter taking the wrong action!  If I keep it at 

fast idle it's great.  It  uses a pickup wire from the voltage regulator 

to trigger it so there isn't any way to put it on the other mag, etc.  

Anyone have any ideas or the same experience with a UMA tach? 

Thanks

Ron DeWees



 	  Quote:

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

larry(at)macsmachine.com
Guest

Posted: Sat Mar 11, 2006 6:44 am Post subject: Unstable UMA Tach

Ron,

I had a UMA tach that would go erratic above 3000 rpm and swapped it out 

for a VDO which

is rock solid throughout its range.  I've got a diagram of how the VDO 

and my EIS are wired to

the ignition switch.  The UMA had a wire coiled around the number 1 plug 

wire and it just wouldn't

work reliably as an impulse reader.

http://www.macsmachine.com/images/electrical/full/Ignition-Dual-Dizzy-and-TP4.gif

Larry McFarland - 601HDS at www.macsmachine.com

ron dewees wrote:

 	  Quote: 	

While on the subject of unstable tachs I have a question myself.  I have 

a UMA tach on my Jab 3300   (0 to 3500 rpm scale) and it's spot-on 

accurate from 1000 rpm to beyond 3100 rpm. The problem is that it just 

stops reading and goes to zero rpms below 950 or so rpms. When it's 

sitting on O rpm I don't know if it's at low idle or stopped.  Don't 

want to grind up a starter taking the wrong action!  If I keep it at 

fast idle it's great.  It  uses a pickup wire from the voltage regulator 

to trigger it so there isn't any way to put it on the other mag, etc.  

Anyone have any ideas or the same experience with a UMA tach? 

Thanks

Ron DeWees

> 

>

>    

>

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

JAPhillipsGA(at)aol.com
Guest

Posted: Sat Mar 11, 2006 8:46 pm Post subject: Unstable UMA Tach

Ron, my tac does the same thing. Under 900 rpm it bounces around. 700 to 900. 

Another thing mine does is after I kill the master the arm does not drop to 

zero. It hangs up at about 600. Then if I flip the master on and off again it 

will drop to zero. I am sure the revs are accurate though as I checked them 

several times with a meter. Bill

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

rdewees(at)mindspring.com
Guest

Posted: Sun Mar 12, 2006 4:46 am Post subject: Unstable UMA Tach

Hi Bill,

I'm like you-- as long as it's accurate in the "bread and butter" zone, 

I guess I can live with it.  Sure good to see your beautiful plane at 

the flyin.  I posted our flyin story in the NavCom  EAA 690 newsletter.  

Looked good to see all the 601s.

 Take care and I am sure we will see you somewhere soon.  FWIW it's a 

lot less hassle flying into WDR and eating at the Spitfire Grill if we 

get a chance. I keep tiinking of flying to T/U airport soon, but doesn't 

look like a lot to see or do unless you are Jim are there.

Blue skies!

Ron



JAPhillipsGA(at)aol.com wrote:



 	  Quote: 	
		  



Ron, my tac does the same thing. Under 900 rpm it bounces around. 700 to 900. 

Another thing mine does is after I kill the master the arm does not drop to 

zero. It hangs up at about 600. Then if I flip the master on and off again it 

will drop to zero. I am sure the revs are accurate though as I checked them 

several times with a meter. Bill

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

planejim(at)bellsouth.net
Guest

Posted: Sun Mar 12, 2006 5:56 am Post subject: Unstable UMA Tach

Ron,



I'll be there all day today (Sun 3-12). Continuing work on airplane. Maybe 

some flying too. I'm at hangar 18 at OPN.



Jim Hoak



do not archive

---

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum