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Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Tue Oct 15, 2013 7:09 am Post subject: diodes

On Oct 14, 2013, at 6:54 AM, Joe wrote:

 	  Quote: 	
		  Yes, diodes are required across contactor coils to prevent voltage spikes.  Voltage spikes, if not suppressed, can damage the switches that supply power to the contactor coils.  With or without the diodes, there is no danger to avionics. 	




Thanks for the clarification Joe.

I've done some research on the contactors I bought at Acft Spru; P/N 11-03161, a contactor manufactured by White - Rogers w/ their product number of 70 111226 6. 

I've asked whether or not the relay IS or IS NOT "protected by a diode to reduce the voltage spike seen when the contactor is turned on.

After contacting the mfg'r and its parent company and getting some initial runaround about internal circuitry being proprietary, I have been told that this contactor does NOT have such a diode....caveat emptor.

I'll be replacing mine w/ the B & C contactors.

Fred



 [quote][b]

ceengland7(at)gmail.com
Guest

Posted: Tue Oct 15, 2013 8:43 am Post subject: diodes

On 10/15/2013 9:55 AM, Fred Klein       wrote:

     

      	  Quote: 	
		  

                On Oct 14, 2013, at 6:54 AM, Joe wrote:

                   	  Quote: 	
		  Yes, diodes are               required across contactor coils to prevent voltage               spikes.  Voltage spikes, if not suppressed, can damage the               switches that supply power to the contactor coils.  With               or without the diodes, there is no danger to avionics. 	
         

       

       Thanks for the clarification Joe.

       

       

       I've done some research on the contactors I bought at Acft         Spru; P/N 11-03161, a contactor manufactured by White - Rogers         w/ their product number of 70 111226 6. 

       

       

       I've asked whether or not the relay IS or IS NOT "protected         by a diode to reduce the voltage spike seen when the contactor         is turned on.

       

       

       After contacting the mfg'r and its parent company and getting         some initial runaround about internal circuitry being         proprietary, I have been told that this contactor does NOT have         such a diode....caveat emptor.

       

       

       I'll be replacing mine w/ the B & C contactors.

       

       

       Fred

       

     	
     I missed the original post, so I might not have all info needed for     a reply, but here goes: not having a diode across a relay's coil (as     purchased) is more the norm than the exception. Diodes for the job     described are dirt cheap (pennies, last time I checked) &     available anywhere you can buy electronic components. If the     contactor does what you need it to do, just add the diode.

     

     Charlie

      [quote][b]

edpav8r(at)yahoo.com
Guest

Posted: Tue Oct 15, 2013 8:48 am Post subject: diodes

Fred,

It would be easier and cheaper to add the diode externally to your existing contactor.  They're available at your local Radio Shack for $3.49 for 25.  If you don't have a RS close by, Digi-Key has them for $0.11 ea. (less in quantity) and their shipping via 1st Class Mail is very reasonable.

Digi-Key:  http://tinyurl.com/m9ywoxc

Radio Shack:  http://tinyurl.com/ksswgfp

Eric



On Oct 15, 2013, at 7:55 AM, Fred Klein <fklein(at)orcasonline.com (fklein(at)orcasonline.com)> wrote:



 	  Quote: 	
		  On Oct 14, 2013, at 6:54 AM, Joe wrote:

 	  Quote: 	
		  Yes, diodes are required across contactor coils to prevent voltage spikes.  Voltage spikes, if not suppressed, can damage the switches that supply power to the contactor coils.  With or without the diodes, there is no danger to avionics. 	




Thanks for the clarification Joe.

I've done some research on the contactors I bought at Acft Spru; P/N 11-03161, a contactor manufactured by White - Rogers w/ their product number of 70 111226 6. 

I've asked whether or not the relay IS or IS NOT "protected by a diode to reduce the voltage spike seen when the contactor is turned on.

After contacting the mfg'r and its parent company and getting some initial runaround about internal circuitry being proprietary, I have been told that this contactor does NOT have such a diode....caveat emptor.

I'll be replacing mine w/ the B & C contactors.

Fred



	


 [quote][b]

infow(at)shaw.ca
Guest

Posted: Tue Oct 15, 2013 10:59 am Post subject: diodes

You can get both contactors and diodes from Van's Aircraft!   Reasonable cost and cheap 

shipping... like most of their parts.

Ron

 	  Quote: 	
		  : On Oct 14, 2013, at 6:54 AM, Joe wrote:

:

:>: Yes, diodes are required across contactor coils to prevent voltage spikes.  Voltage

:>: spikes, if not suppressed, can damage the switches that supply power to the

:>: contactor coils.  With or without the diodes, there is no danger to avionics.

:>:

:

: Thanks for the clarification Joe.

:

:

: I've done some research on the contactors I bought at Acft Spru; P/N 11-03161, a

: contactor manufactured by White - Rogers w/ their product number of 70 111226 6. 

:

:

: I've asked whether or not the relay IS or IS NOT "protected by a diode to reduce the

: voltage spike seen when the contactor is turned on.

:

:

: After contacting the mfg'r and its parent company and getting some initial runaround

: about internal circuitry being proprietary, I have been told that this contactor does

: NOT have such a diode....caveat emptor.

:

:

: I'll be replacing mine w/ the B & C contactors.

:

:

: Fred

:

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


 	  Quote: 	
		  : MATRONICS WEB FORUMS -

: http://www.matronics.com/contribution

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Oct 15, 2013 7:04 pm Post subject: diodes

 	  Quote: 	
		  I missed the original post, so I might not have all info needed for a reply, but here goes: not having a diode across a relay's coil (as purchased) is more the norm than the exception. Diodes for the job described are dirt cheap (pennies, last time I checked) & available anywhere you can buy electronic components. If the contactor does what you need it to do, just add the diode.

 	


   Don't 'replace' . . . modify. Diodes are cheap,

   readily available and non-critical as to electrical

   ratings. My personal favorites are the 1N540X SERIES

   devices where X can be any digit. 



   Radio Shack will sell you two of these in a blister

   pak of two for about $2. See:



  http://tinyurl.com/n6wq2bx



   Everyone who claims to be in the electronics parts

   business will have them at similar or cheaper prices.



   These are all electrically VERY robust . . . smaller

   devices would suffice electrically. But they are

   mechanically robust too. Easier to work with and

   less subject to installer-damage. 



   Here's a couple of articles on the topic . . .



  http://tinyurl.com/nva2xdy



 

  http://tinyurl.com/25wjo7w



   There's a lot of ol' mechanic's tales and hangar

   mythology about system spikes loose in the wild.

   If anyone encounters a convincing tale that

   give you the urge to spend more money or to rip

   out part of an existing system, let's talk about

   it here first.



 

   Bob . . .    [quote][b]

Edwardoc

Joined: 20 Aug 2009
Posts: 8
Location: Kersey, CO 80634

Posted: Fri Apr 29, 2016 12:55 pm Post subject: Re: diodes

At the risk of being shot I have a question concerning how to hook a diode to my new starter contact.  I am replacing the one that came from Vans in 2005 with a Lamar brand contractor but the coil lugs are not labeled S & I like the old one.  I think I have figured out which side of the coil is the 12-V input and the other one I think hooks to ground.  Lamar web site shows two types of hookups depending on a negative or positive switching but not sure where to hook the diode to for the positive switching wiring.  On the old contractor one of the coil lugs was internally grounded but on the Lamar neither one is.  Any inputs.  Couldn't find anything in my searches.



After reading about contractors and voltage spikes, I may have some burned contacts on my key starting switch as I did not install a diode on the starter contractor on 2006 and have been having trouble on and off for two years with my starter acting like it is getting low voltage even though all the voltages check OK under load.  Starter has been rebuilt by SkyTec.  

The problem is on some starts the pinion gear moves forward on the Sky Tec LS starter but not with enough force to engage the gears on the flywheel and thus the starter motor does not turn.  Sometimes holding the key on will cause it to finally engage and start.  Other times it works fine both hot and cold engine.  Other times it will not engage at all unless someone moves the prop slightly while I hold the starter key on and then it engages and the starter cranks the engine fine.

Changing the contractor just to eliminate that as a cause before replacing the key starter switch.

ceengland7(at)gmail.com
Guest

Posted: Fri Apr 29, 2016 1:34 pm Post subject: diodes

On Fri, Apr 29, 2016 at 3:56 PM, Edwardoc <Rv8tor(at)mac.com (Rv8tor(at)mac.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "Edwardoc" <Rv8tor(at)mac.com (Rv8tor(at)mac.com)>

 

 At the risk of being shot I have a question concerning how to hook a diode to my new starter contact.  I am replacing the one that came from Vans in 2005 with a Lamar brand contractor but the coil lugs are not labeled S & I like the old one.  I think I have figured out which side of the coil is the 12-V input and the other one I think hooks to ground.  Lamar web site shows two types of hookups depending on a negative or positive switching but not sure where to hook the diode to for the positive switching wiring.  On the old contractor one of the coil lugs was internally grounded but on the Lamar neither one is.  Any inputs.  Couldn't find anything in my searches.

 

 After reading about contractors and voltage spikes, I may have some burned contacts on my key starting switch as I did not install a diode on the starter contractor on 2006 and have been having trouble on and off for two years with my starter acting like it is getting low voltage even though all the voltages check OK under load.  Starter has been rebuilt by SkyTec.

 The problem is on some starts the pinion gear moves forward on the Sky Tec LS starter but not with enough force to engage the gears on the flywheel and thus the starter motor does not turn.  Sometimes holding the key on will cause it to finally engage and start.  Other times it works fine both hot and cold engine.  Other times it will not engage at all unless someone moves the prop slightly while I hold the starter key on and then it engages and the starter cranks the engine fine.

 Changing the contractor just to eliminate that as a cause before replacing the key starter switch. 

 

 

 



	
If the pinion teeth actually engage the flywheel teeth, but it doesn't turn, then either the starter motor is defective (unlikely, if intermittent) or it isn't seeing full battery voltage. That can be caused by dirty/corroded crimps, terminals, etc, anywhere between the battery positive post and the battery negative post. In other words, don't forget to check the ground path, too. It can also be caused by defective contacts in the solenoid that's mounted on the starter itself. Make yourself an extension wire & hook one end to the heavy B+ terminal on the starter and the other end to your volt meter positive lead. hold the meter negative *directly* on the battery negative post (not on the connector). Push the start button. You should see 8-10 volts on the meter if the prop turns. If it doesn't turn, and you see less than 9 volts, you've got either a bad connection somewhere or a bad battery.

Use the ohm meter function to check the separate starter contactor. It should have 2 big & 1 or 2 small terminals. Measure resistance from the metal frame to each small terminal. If one of them is tied to the frame, it will read near zero ohms on your meter. The other would then read ~4-6 ohms to ground.

If one reads 4-6 ohms to the frame, and the other reads open circuit (infinite resistance), then you've got a contactor with S & I terminals. 

In either case, hook up your diode so the arrow points toward the terminal that reads 4-6 ohms to ground. That is also where you'll hook your control line from your starter switch. B+ from bus to switch to contactor terminal. The other end of the diode goes to ground/frame.

Note that if neither terminal shows low/no resistance to ground, but you read 15-20 ohms between the small terminals, you probably don't have a starter contactor. It's likely a master contactor. Will maybe work for a while, but life may be short.

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Fri Apr 29, 2016 2:02 pm Post subject: Re: diodes

Connect the diode directly across the two small terminals on the Lamar contactor with the arrow (banded end) pointing towards positive.  As far as polarity of the small terminals, it does not matter.  (if I am looking at the correct datasheet)

http://www.aircraftspruce.com/catalog/pdf/lamarsolenoidinstall.pdf

Check terminals for tightness and corrosion on all fat wires between the battery and starter, both positive and negative (ground).

_________________
Joe Gores

Edwardoc

Joined: 20 Aug 2009
Posts: 8
Location: Kersey, CO 80634

Posted: Fri Apr 29, 2016 6:04 pm Post subject: Re: diodes

Thanks much. Now I understand.

Edwardoc

Joined: 20 Aug 2009
Posts: 8
Location: Kersey, CO 80634

Posted: Sun May 01, 2016 7:25 am Post subject: Re: diodes

 	  ceengland7(at)gmail.com wrote: 	
		  On Fri, Apr 29, 2016 at 3:56 PM, Edwardoc <Rv8tor> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "Edwardoc" <Rv8tor>

 

 At the risk of being shot I have a question concerning how to hook a diode to my new starter contact.  I am replacing the one that came from Vans in 2005 with a Lamar brand contractor but the coil lugs are not labeled S & I like the old one.  I think I have figured out which side of the coil is the 12-V input and the other one I think hooks to ground.  Lamar web site shows two types of hookups depending on a negative or positive switching but not sure where to hook the diode to for the positive switching wiring.  On the old contractor one of the coil lugs was internally grounded but on the Lamar neither one is.  Any inputs.  Couldn't find anything in my searches.

 

 After reading about contractors and voltage spikes, I may have some burned contacts on my key starting switch as I did not install a diode on the starter contractor on 2006 and have been having trouble on and off for two years with my starter acting like it is getting low voltage even though all the voltages check OK under load.  Starter has been rebuilt by SkyTec.

 The problem is on some starts the pinion gear moves forward on the Sky Tec LS starter but not with enough force to engage the gears on the flywheel and thus the starter motor does not turn.  Sometimes holding the key on will cause it to finally engage and start.  Other times it works fine both hot and cold engine.  Other times it will not engage at all unless someone moves the prop slightly while I hold the starter key on and then it engages and the starter cranks the engine fine.

 Changing the contractor just to eliminate that as a cause before replacing the key starter switch. 

 

 

 



	
If the pinion teeth actually engage the flywheel teeth, but it doesn't turn, then either the starter motor is defective (unlikely, if intermittent) or it isn't seeing full battery voltage. That can be caused by dirty/corroded crimps, terminals, etc, anywhere between the battery positive post and the battery negative post. In other words, don't forget to check the ground path, too. It can also be caused by defective contacts in the solenoid that's mounted on the starter itself. Make yourself an extension wire & hook one end to the heavy B+ terminal on the starter and the other end to your volt meter positive lead. hold the meter negative *directly* on the battery negative post (not on the connector). Push the start button. You should see 8-10 volts on the meter if the prop turns. If it doesn't turn, and you see less than 9 volts, you've got either a bad connection somewhere or a bad battery.

Use the ohm meter function to check the separate starter contactor. It should have 2 big & 1 or 2 small terminals. Measure resistance from the metal frame to each small terminal. If one of them is tied to the frame, it will read near zero ohms on your meter. The other would then read ~4-6 ohms to ground.

If one reads 4-6 ohms to the frame, and the other reads open circuit (infinite resistance), then you've got a contactor with S & I terminals. 

In either case, hook up your diode so the arrow points toward the terminal that reads 4-6 ohms to ground. That is also where you'll hook your control line from your starter switch. B+ from bus to switch to contactor terminal. The other end of the diode goes to ground/frame.

Note that if neither terminal shows low/no resistance to ground, but you read 15-20 ohms between the small terminals, you probably don't have a starter contactor. It's likely a master contactor. Will maybe work for a while, but life may be short. 	
 	  Quote: 	
		  	
 	  Quote: 	
		  



The pinion gear moves and hits the flywheel ring gear but does not engage the teeth. You can hear it and an observer can see it move and strike the flywheel. SkyTec told me that unless the pinion gear engages the teeth, the starter motor will not begin to rotate until it is full forward.  I have suspected low voltage but once you nudge the prop just a bit the pinion gear slides forward, engages the ring gear and then the starter rotates and spins the prop as if it were normal.  Also I have had occasions where I turn the key and the starter engages normal and get normal rotation and enging start.  The engine dies, I turn the key again and the pinion gear will not engage.  Nudge the prop and fraction of an inch with the key held in start and it engages and I start the engine.  I am going to install a button switch and bypass the key switch for a test if replacing the contractor did not do anything.

ceengland7(at)gmail.com
Guest

Posted: Sun May 01, 2016 8:20 am Post subject: diodes

On Sun, May 1, 2016 at 10:25 AM, Edwardoc <Rv8tor(at)mac.com (Rv8tor(at)mac.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "Edwardoc" <Rv8tor(at)mac.com (Rv8tor(at)mac.com)>

 

 

 ceengland7(at)gmail.com wrote:

 > On Fri, Apr 29, 2016 at 3:56 PM, Edwardoc  wrote:

 >

 > > --> AeroElectric-List message posted by: "Edwardoc"

 > >

 > >  At the risk of being shot I have a question concerning how to hook a diode to my new starter contact.  I am replacing the one that came from Vans in 2005 with a Lamar brand contractor but the coil lugs are not labeled S & I like the old one.  I think I have figured out which side of the coil is the 12-V input and the other one I think hooks to ground.  Lamar web site shows two types of hookups depending on a negative or positive switching but not sure where to hook the diode to for the positive switching wiring.  On the old contractor one of the coil lugs was internally grounded but on the Lamar neither one is.  Any inputs.  Couldn't find anything in my searches.

 > >

 > >  After reading about contractors and voltage spikes, I may have some burned contacts on my key starting switch as I did not install a diode on the starter contractor on 2006 and have been having trouble on and off for two years with my starter acting like it is getting low voltage even though all the voltages check OK under load.  Starter has been rebuilt by SkyTec.

 > >  The problem is on some starts the pinion gear moves forward on the Sky Tec LS starter but not with enough force to engage the gears on the flywheel and thus the starter motor does not turn.  Sometimes holding the key on will cause it to finally engage and start.  Other times it works fine both hot and cold engine.  Other times it will not engage at all unless someone moves the prop slightly while I hold the starter key on and then it engages and the starter cranks the engine fine.

 > >  Changing the contractor just to eliminate that as a cause before replacing the key starter switch. 

 > >

 > >

 > >

 > >

 > >

 > If the pinion teeth actually engage the flywheel teeth, but it doesn't turn, then either the starter motor is defective (unlikely, if intermittent) or it isn't seeing full battery voltage. That can be caused by dirty/corroded crimps, terminals, etc, anywhere between the battery positive post and the battery negative post. In other words, don't forget to check the ground path, too. It can also be caused by defective contacts in the solenoid that's mounted on the starter itself. Make yourself an extension wire & hook one end to the heavy B+ terminal on the starter and the other end to your volt meter positive lead. hold the meter negative *directly* on the battery negative post (not on the connector). Push the start button. You should see 8-10 volts on the meter if the prop turns. If it doesn't turn, and you see less than 9 volts, you've got either a bad connection somewhere or a bad battery.

 >

 >

 > Use the ohm meter function to check the separate starter contactor. It should have 2 big & 1 or 2 small terminals. Measure resistance from the metal frame to each small terminal. If one of them is tied to the frame, it will read near zero ohms on your meter. The other would then read ~4-6 ohms to ground.

 >

 >

 > If one reads 4-6 ohms to the frame, and the other reads open circuit (infinite resistance), then you've got a contactor with S & I terminals. 

 >

 >

 > In either case, hook up your diode so the arrow points toward the terminal that reads 4-6 ohms to ground. That is also where you'll hook your control line from your starter switch. B+ from bus to switch to contactor terminal. The other end of the diode goes to ground/frame.

 >

 >

 > Note that if neither terminal shows low/no resistance to ground, but you read 15-20 ohms between the small terminals, you probably don't have a starter contactor. It's likely a master contactor. Will maybe work for a while, but life may be short.

 

 >

 

 >

 >

 > The pinion gear moves and hits the flywheel ring gear but does not engage the teeth. You can hear it and an observer can see it move and strike the flywheel. SkyTec told me that unless the pinion gear engages the teeth, the starter motor will not begin to rotate until it is full forward.  I have suspected low voltage but once you nudge the prop just a bit the pinion gear slides forward, engages the ring gear and then the starter rotates and spins the prop as if it were normal.  Also I have had occasions where I turn the key and the starter engages normal and get normal rotation and enging start.  The engine dies, I turn the key again and the pinion gear will not engage.  Nudge the prop and fraction of an inch with the key held in start and it engages and I start the engine.  I am going to install a button switch and bypass the key switch for a test if replacing the contractor did not do anything.

 



	


That sounds like you might have a physical/mechanical issue, rather than an electrical one. There are clearance specs for the pinion to ring gear mesh. If the pinion is hitting the ring itself, it can't mesh its teeth with the ring gear teeth. Ask SkyTec for their clearance specs. For a quick check, look at the ring gear teeth & pinion teeth. The shiny (contact) area shouldn't extend all the way to the bottom of the V between teeth. You may need to shim the starter's base away from the motor mounting surface slightly.

tshankland(at)sbcglobal.n
Guest

Posted: Sun May 01, 2016 8:37 am Post subject: diodes

---

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Sun May 01, 2016 8:44 am Post subject: Re: diodes

Agree with Charlie. Sounds like a timing or alignment issue between the ring gear and starter.

_________________
Joe Gores

Edwardoc

Joined: 20 Aug 2009
Posts: 8
Location: Kersey, CO 80634

Posted: Sun May 01, 2016 12:57 pm Post subject: Re: diodes

[/quote]

That sounds like you might have a physical/mechanical issue, rather than an electrical one. There are clearance specs for the pinion to ring gear mesh. If the pinion is hitting the ring itself, it can't mesh its teeth with the ring gear teeth. Ask SkyTec for their clearance specs. For a quick check, look at the ring gear teeth & pinion teeth. The shiny (contact) area shouldn't extend all the way to the bottom of the V between teeth. You may need to shim the starter's base away from the motor mounting surface slightly.[/quote]



Thanks.  Another mechanic had suggested shimming the starter slightly to ensure just a little bit more clearance between the teeth.  I had resisted this since a loner SkyTec LS starter seemed to work fine although I did not use it for more then about 5-6 starts but it never hung up.  Will call SkyTec tomorrow to see what their opinion is about the shims.  Thanks again. 	  Quote:

ceengland7(at)gmail.com
Guest

Posted: Sun May 01, 2016 1:55 pm Post subject: diodes

On Sun, May 1, 2016 at 3:57 PM, Edwardoc <Rv8tor(at)mac.com (Rv8tor(at)mac.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "Edwardoc" <Rv8tor(at)mac.com (Rv8tor(at)mac.com)>

 

 	


 That sounds like you might have a physical/mechanical issue, rather than an electrical one. There are clearance specs for the pinion to ring gear mesh. If the pinion is hitting the ring itself, it can't mesh its teeth with the ring gear teeth. Ask SkyTec for their clearance specs. For a quick check, look at the ring gear teeth & pinion teeth. The shiny (contact) area shouldn't extend all the way to the bottom of the V between teeth. You may need to shim the starter's base away from the motor mounting surface slightly.[/quote]

 

 Thanks.  Another mechanic had suggested shimming the starter slightly to ensure just a little bit more clearance between the teeth.  I had resisted this since a loner SkyTec LS starter seemed to work fine although I did not use it for more then about 5-6 starts but it never hung up.  Will call SkyTec tomorrow to see what their opinion is about the shims.  Thanks again.

 >

 



 [/quote]

Remember, this stuff ain't rocket surgery. There's a reason a lot of people put 'aircraft quality' in quotes. And that's why Lyc has clearance specs, and methodology to check for it, and compensate if necessary.

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