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rv-9a-online(at)telus.net
Guest

Posted: Wed Sep 10, 2008 2:35 pm Post subject: Switch problem ***MAJOR UPDATE***

I was wrong about my replacement switch--- I was looking at the wrong one.

In fact, it IS failing, and the fast-on insulation is discolored.  I

discovered this by detecting overheating switches on my panel today.



Furthermore, not only was the STROBE switch very hot, but the WIG-WAG and

TAXI switches were hot as well.  I discovered this today. On the ground, my

panel was feeling warm, and I touched the back these switches.  I burned my

finger on the STROBE switch (hurt for an hour), and the other switches were

hot as well, but not quite as bad.



These are the switches that are most often ON in flight (current flows

through one pole of the TAXI and LANDING switches when WIG-WAG is on).  I

turned them OFF, turned on my LANDING light switch, and it got hot as well.

None of the other switches (MASTER (replaced once), PITOT (rarely used), NAV

(rarely used), FLAPS and BOOST PUMP and AVIONICS were warm when operated.



So I now have four more switch failures!  This is now a total of 6 failures

in my a/c in 2.5 years.  All are Carling switches.



I will be replacing all of the heavy load carrying switches in my A/C

immediately with another brand.  In my opinion, all of these Carling

switches are suspect and everyone should check them for overheating.



Bob, this looks like a serious issue, in need of some further pursuit!  



Thanks,

Vern


--> <rv-9a-online(at)telus.net>



I checked the switch that I installed as a replacement for the one that I

fried about 100 hours ago.  No sign of external damage or discoloration on

the new switch.



My failed switch was installed in 2005, purchased somewhat earlier.  I had

two switches that had loose rivets, so I'm wondering if there was a QC

problem with the Carling switches made about that time.  It would be

interesting to see the date codes on the failed switches.



My failed switch says C0344 Mexico.  My guess was this is a date code (44th

week in 2003?).  The one Bob analysed says 9936 Mexico on it.



Vern

bob(at)bob-white.com
Guest

Posted: Wed Sep 10, 2008 5:22 pm Post subject: Switch problem ***MAJOR UPDATE***

Hi Vern,



Check the crimps on your faston connectors.  If the crimps are getting

hot they could be conducting heat into the switch tabs.  The simplest

way to check would be to make a male faston jumper and replace one of

the switches that is getting hot, then turn on the master.



It might be a bad batch of switches, but it would be worth checking the

crimps before pulling all of them out.



Bob W.



On Wed, 10 Sep 2008 15:33:02 -0700

"Vernon Little" <rv-9a-online(at)telus.net> wrote:



 	  Quote: 	
		   

 

 I was wrong about my replacement switch--- I was looking at the wrong one.

 In fact, it IS failing, and the fast-on insulation is discolored.  I

 discovered this by detecting overheating switches on my panel today.

 

 Furthermore, not only was the STROBE switch very hot, but the WIG-WAG and

 TAXI switches were hot as well.  I discovered this today. On the ground, my

 panel was feeling warm, and I touched the back these switches.  I burned my

 finger on the STROBE switch (hurt for an hour), and the other switches were

 hot as well, but not quite as bad.

 

 These are the switches that are most often ON in flight (current flows

 through one pole of the TAXI and LANDING switches when WIG-WAG is on).  I

 turned them OFF, turned on my LANDING light switch, and it got hot as well.

 

 

 None of the other switches (MASTER (replaced once), PITOT (rarely used), NAV

 (rarely used), FLAPS and BOOST PUMP and AVIONICS were warm when operated.

 

 So I now have four more switch failures!  This is now a total of 6 failures

 in my a/c in 2.5 years.  All are Carling switches.

 

 I will be replacing all of the heavy load carrying switches in my A/C

 immediately with another brand.  In my opinion, all of these Carling

 switches are suspect and everyone should check them for overheating.

 

 Bob, this looks like a serious issue, in need of some further pursuit!  

 

 Thanks,

 Vern

 

 

 

 --> <rv-9a-online(at)telus.net>

 

 I checked the switch that I installed as a replacement for the one that I

 fried about 100 hours ago.  No sign of external damage or discoloration on

 the new switch.

 

 My failed switch was installed in 2005, purchased somewhat earlier.  I had

 two switches that had loose rivets, so I'm wondering if there was a QC

 problem with the Carling switches made about that time.  It would be

 interesting to see the date codes on the failed switches.

 

 My failed switch says C0344 Mexico.  My guess was this is a date code (44th

 week in 2003?).  The one Bob analysed says 9936 Mexico on it.

 

 Vern

 


	




-- 

N93BD - Rotary Powered BD-4 - http://www.bob-white.com

3.8 Hours Total Time and holding

Cables for your rotary installation - http://roblinstores.com/cables/

rv-9a-online(at)telus.net
Guest

Posted: Wed Sep 10, 2008 6:31 pm Post subject: Switch problem ***MAJOR UPDATE***

I will check this for sure, but the evidence is contrary.  If it was the

crimps that were the source, they should all be discolored.  In addition, I

felt the terminals when operating to see if they were loose.  They were not,

and they were not as hot as the switch. 



I pulled apart one of the failed switches (from one of the two that failed

in 2006) and it was damaged, similar to Bob's failure analysis on his

website.



The terminals are the Avikrimp type and attached using a proper ratcheting

crimp tool.



I've ordered a batch of Honeywell Micro Switch switches as replacements.  I

will pull all of the offending Carling switches and redo the burnt fastons

on the Strobe supply switch (for the second time).  I will probably

sacrifice another one of the Carling switches to failure analysis gods to

see if the internals are fried like the first one.



Fortunately, the switches run in a row along the bottom of my panel and are

easy to replace.  See

http://www.vx-aviation.com/rv-9a/photos/Electrical/115_1542_1.jpg.  It

should only take me an hour to do the major offenders and get back in the

air.  Right now, I've grounded my a/c due to this problem.



Stay tuned.



Vern



--

nuckolls.bob(at)cox.net
Guest

Posted: Thu Sep 11, 2008 5:17 am Post subject: Switch problem ***MAJOR UPDATE***

At 07:20 PM 9/10/2008 -0600, you wrote:

 	  Quote: 	
		  



Hi Vern,



Check the crimps on your faston connectors.  If the crimps are getting

hot they could be conducting heat into the switch tabs.  The simplest

way to check would be to make a male faston jumper and replace one of

the switches that is getting hot, then turn on the master.



It might be a bad batch of switches, but it would be worth checking the

crimps before pulling all of them out.



Bob W.


	


   An excellent suggestion for covering all the bases!

   Carling has been in this business for a very long time

   and their total output of switches is probably 1000+ times

   greater than what goes into airplanes. I can see

   the occasional 'batch' problems with process but

   Vern's experience is mystifying.



   The simple-ideas of physics that drive conditions

   he's observed are solid and irrefutable. We just need

   to carefully sift the sand. If anyone else has a

   suggestion for the pursuit of knowledge, it's time

   to bring it up.



   Vern, what fast-on terminals did you use and which

   tool was used to apply them? Save all the pieces

   and parts that are replaced. They can yield important

   information in the 'autopsy'.



   Bob . . .

nuckolls.bob(at)cox.net
Guest

Posted: Thu Sep 11, 2008 5:17 am Post subject: Switch problem ***MAJOR UPDATE***

At 07:26 PM 9/10/2008 -0700, you wrote:

 	  Quote: 	
		  

<rv-9a-online(at)telus.net>



I will check this for sure, but the evidence is contrary.  If it was the

crimps that were the source, they should all be discolored.  In addition, I

felt the terminals when operating to see if they were loose.  They were not,

and they were not as hot as the switch.



I pulled apart one of the failed switches (from one of the two that failed

in 2006) and it was damaged, similar to Bob's failure analysis on his

website.



The terminals are the Avikrimp type and attached using a proper ratcheting

crimp tool.



I've ordered a batch of Honeywell Micro Switch switches as replacements.  I

will pull all of the offending Carling switches and redo the burnt fastons

on the Strobe supply switch (for the second time).  I will probably

sacrifice another one of the Carling switches to failure analysis gods to

see if the internals are fried like the first one.



Fortunately, the switches run in a row along the bottom of my panel and are

easy to replace.  See

http://www.vx-aviation.com/rv-9a/photos/Electrical/115_1542_1.jpg.  It

should only take me an hour to do the major offenders and get back in the

air.  Right now, I've grounded my a/c due to this problem.



Stay tuned.


	


    Sounds like a plan.



    Bob . . .

rv-9a-online(at)telus.net
Guest

Posted: Thu Sep 11, 2008 8:10 am Post subject: Switch problem ***MAJOR UPDATE***

OK, here's the first data from my switch failure:  



- The following is a drawing of my landing/taxi/wig-wag circuit.  Please

note that the Strobe circuit is straightforward, with a 3-1 switch connected

to the main bus.  All four of these switches are getting hot:  TAXI,

LANDING, FLASH and STROBE.

http://www.vx-aviation.com/rv-9a/photos/Electrical/wigwag.jpg



- The following are similar photos of the failed switches, in-situ.  Left to

right:  FLASH switch (hot), STROBE switch (burned fast-ons), NAV switch (no

problems to date)



http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0936_1.JPG

http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0935_2.JPG



The only discernable problem from these photos is the burned fast-ons, but

the switch was dangerously hot to touch in operation.  The FLASH switch

(just visable on the left) gets hot (but not as hot) as well, but no burned

terminals.



My order for new switches arives today (gotta love Digikey in Canada:

ordered at 4:45 pm yesterday, will have them here by noon today... For $8.00

shipping).   I will pull & replace the old switches, and replace the burned

fast-ons.  I'll keep them for F/A.



All of my terminals were purchased either from Steinair or Digikey-- all are

Molex Avikrimp: http://www.molex.com/pdm_docs/sd/190020002_sd.pdf

The crimper was also purchased from Steinair and is similar to:

http://www.steinair.com/images/store/panels/sat001.jpg or

http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?account=X358218;sear

ch=RCT-1;search=PIDG%20Style%20Crimp%20Tool;limit=product;v .0



Stay tuned, I will post more of my findings as I rework my a/c.



Vern



--

david.nelson(at)pobox.com
Guest

Posted: Thu Sep 11, 2008 9:03 am Post subject: Switch problem ***MAJOR UPDATE***

Hi Vernon,



I noticed something odd in



http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0935_2.JPG



It's kinda hard to see the fast-on in the background, so I'm not sure. 

Are both fast-on's discolored or just the one in the foreground?  Also, 

there appears to be some discoloration of the wire itself for the fast-on 

in the background.  Is this just a shadow?



The fast-on tabs and their associated rivets don't appear to be 

discolored.



Just going on the pictures, seems to me that the crimp just is not up to 

the task.  I'll be interested in hearing what Bob sees.



Thanks for sharing,



 	 /\/elson



~~  Lately my memory seems to be like a steel trap .... without any spring.  ~~



On Thu, 11 Sep 2008, Vernon Little wrote:



[quote] 



 OK, here's the first data from my switch failure:



 - The following is a drawing of my landing/taxi/wig-wag circuit.  Please

 note that the Strobe circuit is straightforward, with a 3-1 switch connected

 to the main bus.  All four of these switches are getting hot:  TAXI,

 LANDING, FLASH and STROBE.

 http://www.vx-aviation.com/rv-9a/photos/Electrical/wigwag.jpg



 - The following are similar photos of the failed switches, in-situ.  Left to

 right:  FLASH switch (hot), STROBE switch (burned fast-ons), NAV switch (no

 problems to date)



 http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0936_1.JPG



 The only discernable problem from these photos is the burned fast-ons, but

 the switch was dangerously hot to touch in operation.  The FLASH switch

 (just visable on the left) gets hot (but not as hot) as well, but no burned

 terminals.



 My order for new switches arives today (gotta love Digikey in Canada:

 ordered at 4:45 pm yesterday, will have them here by noon today... For $8.00

 shipping).   I will pull & replace the old switches, and replace the burned

 fast-ons.  I'll keep them for F/A.



 All of my terminals were purchased either from Steinair or Digikey-- all are

 Molex Avikrimp: http://www.molex.com/pdm_docs/sd/190020002_sd.pdf

 The crimper was also purchased from Steinair and is similar to:

 http://www.steinair.com/images/store/panels/sat001.jpg or

 http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?account=X358218;sear

 ch=RCT-1;search=PIDG%20Style%20Crimp%20Tool;limit=product;v .0



 Stay tuned, I will post more of my findings as I rework my a/c.



 Vern



 --

retasker(at)optonline.net
Guest

Posted: Thu Sep 11, 2008 10:12 am Post subject: Switch problem ***MAJOR UPDATE***

I noticed the same thing.  Have you ever done a pull test with some of 

the terminals crimped with this tool?  The depth of the crimp looks 

somewhat shallow compared to the ones on my plane, but it could be an 

illusion from the photo or maybe the plastic could have "relaxed" due to 

the heat.



Dick Tasker



David E. Nelson wrote:

[quote] 

 <david.nelson(at)pobox.com>

 Hi Vernon,



 I noticed something odd in



 http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0935_2.JPG



 It's kinda hard to see the fast-on in the background, so I'm not sure. 

 Are both fast-on's discolored or just the one in the foreground?  

 Also, there appears to be some discoloration of the wire itself for 

 the fast-on in the background.  Is this just a shadow?



 The fast-on tabs and their associated rivets don't appear to be 

 discolored.



 Just going on the pictures, seems to me that the crimp just is not up 

 to the task.  I'll be interested in hearing what Bob sees.



 Thanks for sharing,



      /\/elson



 ~~  Lately my memory seems to be like a steel trap .... without any 

 spring.  ~~



 On Thu, 11 Sep 2008, Vernon Little wrote:



> 

> <rv-9a-online(at)telus.net>

>

> OK, here's the first data from my switch failure:

>

> - The following is a drawing of my landing/taxi/wig-wag circuit.  Please

> note that the Strobe circuit is straightforward, with a 3-1 switch 

> connected

> to the main bus.  All four of these switches are getting hot:  TAXI,

> LANDING, FLASH and STROBE.

> http://www.vx-aviation.com/rv-9a/photos/Electrical/wigwag.jpg

>

> - The following are similar photos of the failed switches, in-situ.  

> Left to

> right:  FLASH switch (hot), STROBE switch (burned fast-ons), NAV 

> switch (no

> problems to date)

>

> http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0936_1.JPG

>

> The only discernable problem from these photos is the burned 

> fast-ons, but

> the switch was dangerously hot to touch in operation.  The FLASH switch

> (just visable on the left) gets hot (but not as hot) as well, but no 

> burned

> terminals.

>

> My order for new switches arives today (gotta love Digikey in Canada:

> ordered at 4:45 pm yesterday, will have them here by noon today... 

> For $8.00

> shipping).   I will pull & replace the old switches, and replace the 

> burned

> fast-ons.  I'll keep them for F/A.

>

> All of my terminals were purchased either from Steinair or Digikey-- 

> all are

> Molex Avikrimp: http://www.molex.com/pdm_docs/sd/190020002_sd.pdf

> The crimper was also purchased from Steinair and is similar to:

> http://www.steinair.com/images/store/panels/sat001.jpg or

> http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?account=X358218;sear 

>

> ch=RCT-1;search=PIDG%20Style%20Crimp%20Tool;limit=product;v .0

>

> Stay tuned, I will post more of my findings as I rework my a/c.

>

> Vern

>

> --

rv-9a-online(at)telus.net
Guest

Posted: Thu Sep 11, 2008 10:42 am Post subject: Switch problem ***MAJOR UPDATE***

Hi Nelson.  Both tabs are discolored, although the one in the foreground is

worse.  There is some discoloration on the wire you mentioned.  I think that

this is from the adhesive residue of the wire label that dried up and fell

off due to the heat.  I will inspect more closely when I replace the

switches.



As for the crimp, I'll save the tab and stub wire for F/A.



You are right about the tabs and rivets, although the first failure I had in

2006 had discoloration.  The 2006 failure also had a tripping CB, so it may

have been a failure similar to the one Bob documented on his web site.



The new Micro Switch switches arrived at 9:45 this AM (17 hour delivery from

Digikey!)have a slightly higher rating (20A/125V vs 15A/125V) and the

construction seems to be more refined, with solid rivets vs hollow rivets

and a closer tolerance on the moulding to prevent the tabs from rotating.  I

don't have any knowledge of the internal construction, though.  They are a

lot more expensive, so hopefully price and quality are positively

correlated.



Vern



--

rv-9a-online(at)telus.net
Guest

Posted: Thu Sep 11, 2008 10:49 am Post subject: Switch problem ***MAJOR UPDATE***

Hi Dick.  I do a pull test on every crimp, although this is not a direct

measurement of termination resistance.

One thing for sure, it's readily apparent why we don't use PVC insulated

terminals... They insulation would have melted.



As for the depth of the crimp, it's tough to tell how the metal ferrule has

crimped by looking through the insulation.  The insulation is very tough and

tends to relax a bit after crimping.



I hope to get to the hangar today, so I'll provide an update later tonight

or tomorrow.



Vern



--

nuckolls.bob(at)cox.net
Guest

Posted: Thu Sep 11, 2008 1:18 pm Post subject: Switch problem ***MAJOR UPDATE***

The photo at:



http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0935_2.JPG



   shows very localized discoloration of the terminal

   insulator. There's a large temperature gradient when

   you consider heat flow path from a high-resistance

   contact within the switch out through riveted joint,

   terminal tab, fast-on socket and to the plastic insulator.



   I'm not seeing any signs of heating of the switch-tab

   or the fast-on socket. The fact you ARE seeing so much

   effects of heating due to poor contact in so many places

   places the application tool in question. See the wire-

   grip photos at:



http://www.aeroelectric.com/articles/CrimpTools/crimptools.html



   This is a critical issue for mating tools-to-terminals-to-wire.



   If you would care to send me some exemplar terminals installed

   on wires, I'd be pleased to get a look at the microscopic details

   of the wire grip.



   Bob . . .

rv-9a-online(at)telus.net
Guest

Posted: Thu Sep 11, 2008 4:35 pm Post subject: Switch problem ***MAJOR UPDATE***

Hi Bob.  Thanks for your comments.  See my reply, plus my new findings of

today:



 	  Quote: 	
		   

    The photo at:

 

 http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0935_2.JPG

 

    shows very localized discoloration of the terminal

    insulator. There's a large temperature gradient when

    you consider heat flow path from a high-resistance

    contact within the switch out through riveted joint,

    terminal tab, fast-on socket and to the plastic insulator.

 

    I'm not seeing any signs of heating of the switch-tab

    or the fast-on socket. The fact you ARE seeing so much

    effects of heating due to poor contact in so many places

    places the application tool in question. See the wire-

    grip photos at:

 

 http://www.aeroelectric.com/articles/CrimpTools/crimptools.html

 

    This is a critical issue for mating tools-to-terminals-to-wire.

 

    If you would care to send me some exemplar terminals installed

    on wires, I'd be pleased to get a look at the microscopic details

    of the wire grip.

 

    Bob . . .

 


	


After removing all of my SPDT switches and replacing them, I did, indeed

find some discoloration of two terminals on the Strobe switch.  Since the

Landing light was getting a bit warm as well, I looked at it-- no

discoloration.  I opened up the switches and looked at the rocker bars, see

photo:  http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0955_1.JPG

and http://www.vx-aviation.com/rv-9a/photos/Electrical/IMG_0956_2.JPG.  



In both cases, the landing light rocker is on the left, and the strobe

rocker on the right.  It's not apparent from the photos, but the strobe

rocker has discolored.  The second photo shows that the lubricating grease

has carbonized due to internal heating.  Also, the center rivet on the

switch was very loose, leading to a significant voltage drop across the

switch of 2 volts when measure in-situ with strobes operating (and it got

very hot!). 



Both rockers were relatively flat, with only slight curls to them.



So it's safe to conclude that both the strobe switch and the related

fast-ons have heat damage.  The landing light switch was in much better

condition, with no fast-on discoloration or obvious internal problems.  



What is causing these recurrent problems?  One theory is bad crimps, the

other is bad switches.  Maybe one is causing the other.  If a crimp is

faulty, and causes heating of the terminal, perhaps this triggers problems

in the switches, which then heat up as well.  Or maybe it's the other way

around.  To test this theory, I replaced the strobe switch and left the

discolored fast-ons in place:  No problem, switch and terminals remained

cool, and voltage drop across the switch was unmeasurable.  Seems to

indicate a switch problem, but not conclusive.  I later cut off the

discolored fast-ons and I'l be mailing them to Bob along with some test

crimps from my crimper.



BTW, I tested all of the replacement switches in my A/C.  No heat problems

to report.  Time will tell, of course.



I'd sure like to hear from others-- run out and feel your switches and

terminals and let us know the results.  If I am the only one with these

problems, then I need to dig deeper.



Vern

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Fri Sep 12, 2008 5:03 am Post subject: Re: Switch problem ***MAJOR UPDATE***

Why has the problem only happened with toggles as opposed to rockers?



Obviously the switch is the problem. Has ANYONE called Carling Switch and bitched?? Why not? What do they say? Despite what Bob says, 115 VAC switches should never be used for LV DC high-current applications. Do what the manufacturer suggests. That's what's printed on the side of the switch Bubela. Otherwise you're on your own.



Bob--"Gas-Tight" Can you even SHOW me a "Gas-Tight" Faston connection? This silly regression to concern about gas-tight Fastons is wildly delusional. In my previous life we used Fastons for decades at 25 Amps DC with short excursions to 300 Amps with nary a failure.  A hundred different people did the installation. The choice of tools by the manufacturing department never became so ANAL. 



 I supply 50A Fastons with my high-current SSRs and I don't lose a wink of sleep. The terminals don't get as warm as a kitten's belly.



"Everything you've learned in school as 'obvious' becomes less and less obvious as you begin to study the universe. For example, there are no solids in the universe. There's not even a suggestion of a solid. There are no absolute continuums. There are no surfaces. There are no straight lines." 



-R. Buckminster Fuller

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

Sam

Joined: 18 May 2008
Posts: 135

Posted: Fri Sep 12, 2008 6:29 am Post subject: Switch problem ***MAJOR UPDATE***

Eric, this is a new and interesting topic.  No need to come in swinging, let's just be polite and look at the science.

 	  Quote: 	
		  	
Sam Hoskins

www.samhoskins.blogspot.com

 

On Fri, Sep 12, 2008 at 8:03 AM, Eric M. Jones <emjones(at)charter.net (emjones(at)charter.net)> wrote:

[quote] --> AeroElectric-List message posted by: "Eric M. Jones" <emjones(at)charter.net (emjones(at)charter.net)>

 

 Why has the problem only happened with toggles as opposed to rockers?

 

 Obviously the switch is the problem. Has ANYONE called Carling Switch and bitched?? Why not? What do they say? Despite what Bob says, 115 VAC switches should never be used for LV DC high-current applications. Do what the manufacturer suggests. That's what's printed on the side of the switch Bubela. Otherwise you're on your own.

  

 Bob--"Gas-Tight" Can you even SHOW me a "Gas-Tight" Faston connection? This silly regression to concern about gas-tight Fastons is wildly delusional. In my previous life we used Fastons for decades at 25 Amps DC with short excursions to 300 Amps with nary a failure.  A hundred different people did the installation. The choice of tools by the manufacturing department never became so ANAL.

  

  I supply 50A Fastons with my high-current SSRs and I don't lose a wink of sleep. The terminals don't get as warm as a kitten's belly.

 

 "Everything you've learned in school as 'obvious' becomes less and less obvious as you begin to study the universe. For example, there are no solids in the universe. There's not even a suggestion of a solid. There are no absolute continuums. There are no surfaces. There are no straight lines."

  

 -R. Buckminster Fuller

 

 --------

 Eric M. Jones

 www.PerihelionDesign.com

 113 Brentwood Drive

 Southbridge, MA 01550

 (508) 764-2072

 emjones(at)charter.net (emjones(at)charter.net)

 

 

 

 

 Read this topic online here:

 

 [url=http://forums.matronics.com/viewtopic.php?p 3943#203943]http://forums.matronics.com/viewtopic.php?p 3943#203943[/url]

 

 

 

 

 

 

 

 

 

 

 [b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

rv-9a-online(at)telus.net
Guest

Posted: Fri Sep 12, 2008 7:24 am Post subject: Switch problem ***MAJOR UPDATE***

Hi Eric.



When I had my first switch failure (Master Switch) in 2006, I returned it to

my supplier (well know aviation electrics company), requesting F/A.  I heard

nothing.  Being a practical person, I thought that it was an outlier,

purchased a new one and moved on.



The subsequent failure of the Strobe switch a couple of years ago got me a

lot more concerned, but the recent failures now have me ripping out the

Carling switches and replacing with another brand.  I have no definitive

evidence that all Carling switches are bad, just my experiences on my

airframe.



The correct course of action is for my supplier to work with Carling on

this.  Tried that, no result.  I have no economic skin in this game, but my

supplier does.  I just want to solve my problem and warn others by sharing

my results.  If others are having similar problems, then it can be

determined that my problems are not unique.



One thing that is definitive:  all of the failing switches have loose

rivets.  I don't think they started that way, so it may be an effect of

overheating, not the cause.  Nevertheless, I can envision a thermal runaway

situation as a rivet gets resistive.



I'm sending some stuff to Bob for his investigation, so he can be the

repository of information on this issue.



Vern



[quote] --

rv-9a-online(at)telus.net
Guest

Posted: Fri Sep 12, 2008 8:42 am Post subject: Switch problem ***MAJOR UPDATE***

..

 	  Quote: 	
		   Despite what Bob says, 115 VAC switches should never be used 

 for LV DC high-current applications. Do what the manufacturer 

 suggests. That's what's printed on the side of the switch 

 Bubela. Otherwise you're on your own.

 

..
	


 	  Quote: 	
		   --------

 Eric M. Jones

 www.PerihelionDesign.com

..
	




Hi again Eric.  Just to comment on what you said:



"DC Rule of Thumb

For those switches that list an AC voltage rating only, the "DC Rule of

Thumb" can be applied for determining the switch's maximum DC current

rating. This "rule" states the highest amperage on the switch should perform

satisfactorily up to 30 volts DC. For example, a switch which is rated at

10A 250VAC; 15A 125VAC; 3/4HP 125-250VAC, will be likely to perform

satisfactorily at 15 amps up to 30 volts DC (VDC)"

http://www.carlingtech.com/products/switches/learn_more.asp?page=switches_am

p-rating



Therefore, all of my Carling switches are being used according to the

manufacturers recommendations.  The only gotcha is that the switches are not

rated for operating below 0 degrees C.  This is probably because the

switches are not sealed from condensing moisture.  This is not a problem

where I live.



Vern

Speedy11(at)aol.com
Guest

Posted: Fri Sep 12, 2008 8:42 am Post subject: Switch problem ***MAJOR UPDATE***

Vern,

 Very interesting problem and investigation.  Thanks for sharing it  with us.

 I noticed that the fast-on is stamped 18-22 gauge and your wiring diagram  lists 14 gauge wire.  Could that difference have caused a weak crimp?

 Stan Sutterfield

  

  	  Quote: 	
		  What is    causing these recurrent problems?  One theory is bad crimps, the

other    is bad switches.  Maybe one is causing the other.  If a crimp    is

faulty, and causes heating of the terminal, perhaps this triggers    problems

in the switches, which then heat up as well.  Or maybe it's    the other way

around. 	


 

  



Psssst...Have you heard the news? There's a new fashion blog, plus the latest fall trends and hair styles at StyleList.com.

  [quote][b]

rv-9a-online(at)telus.net
Guest

Posted: Fri Sep 12, 2008 9:24 am Post subject: Switch problem ***MAJOR UPDATE***

The photo is of the strobe switch, the  wiring diagram is of the landing/taxi/wig-wag circuit.  That's the  confusion.  The strobe uses 18 ga. wiring.  The "FLASH" switch is on  the left in the photos, with the blue terminals.

  

 Good eyes!

  

 Thanks, Vern

 [quote]   

   --

rv-9a-online(at)telus.net
Guest

Posted: Fri Sep 12, 2008 4:24 pm Post subject: Switch problem ***MAJOR UPDATE***

Bob:  A couple of switches, the burnt fast-ons, and some sample terminations

on your way by airmail today.  Hope you have time to add a learned second

opinion after you have a look.



Thanks, Vern



[quote] --

nuckolls.bob(at)cox.net
Guest

Posted: Fri Sep 12, 2008 7:24 pm Post subject: Switch problem ***MAJOR UPDATE***

At 06:03 AM 9/12/2008 -0700, you wrote:

 	  Quote: 	
		  



Why has the problem only happened with toggles as opposed to rockers?


	


   Don't know that it's been this selective. Just because

   you're not aware of someone's difficulties/observations

   doesn't mean they've not happened.



 	  Quote: 	
		  Obviously the switch is the problem. Has ANYONE called Carling Switch and 

bitched?? Why not? What do they say? Despite what Bob says, 115 VAC 

switches should never be used for LV DC high-current applications. Do what 

the manufacturer suggests. That's what's printed on the side of the switch 

Bubela. Otherwise you're on your own.


	


    Really? It appears that you've not studied the physics

    of making connections between wires and terminals

    nor is it apparent that you've studied and understood

    the physics of relay and switch contacts.



    It is also glaringly obvious that you have not read the

    article at:



http://www.aeroelectric.com/articles/Switch_Ratings.pdf



    nor studied the ratings charts for switches excerpted

    from Honeywell data similar to that found here:



http://aeroelectric.com/Mfgr_Data/Switches/Microswitch_TL-Series.pdf



    Okay Eric, call Carling. Exactly what would you say?

    What makes you think you'll be placed in contact with

    someone that actually understands what's happening? What

    would you expect them to say in response? If you light into

    Carling with the same display of ignorance as you've

    blessed us with here, it is unlikely their response

    would be helpful to you or anyone else.



 	  Quote: 	
		  Bob--"Gas-Tight" Can you even SHOW me a "Gas-Tight" Faston connection? 

This silly regression to concern about gas-tight Fastons is wildly 

delusional. In my previous life we used Fastons for decades at 25 Amps DC 

with short excursions to 300 Amps with nary a failure.  A hundred 

different people did the installation. The choice of tools by the 

manufacturing department never became so ANAL.


	


   Eric, 'gas tight' has nothing to do with fast-ons in

   particular. We're not talking about interface between

   the fast-on and the switch tab. We're talking about

   the interface between strands of wire and the terminal

   as determined by the design of the crimp tool.



   If you had bothered to read and understand the article

   I cited at:



http://aeroelectric.com/articles/CrimpTools/crimptools.html



   then this would have been clear to you.



   Understand this my friend, gas-tight is not my term

   but that of my teachers who have accurately and patiently

   shared their their knowledge and understanding in volumes

   of printed data which is just as accessible to you

   as it is to me.



   Further there are gas-tight components of the interface

   between a fast-on female and the mating tab. If you had

   bothered to attend the seminar I offered at Plymouth

   a few years ago (I would have let you sit in for free)

   this would all have been explained to you.



 	  Quote: 	
		  I supply 50A Fastons with my high-current SSRs and I don't lose a wink of 

sleep. The terminals don't get as warm as a kitten's belly.


	


   I'm pleased that you're sleeping well. I often lay

   awake for hours . . . my head may be busy figuring

   out ways to disassemble the simple-ideas of a failure

   into a root cause . . . or assembling the same simple-

   ideas into a new and useful product.



 	  Quote: 	
		  "Everything you've learned in school as 'obvious' becomes less and less 

obvious as you begin to study the universe. For example, there are no 

solids in the universe. There's not even a suggestion of a solid. There 

are no absolute continuums. There are no surfaces. There are no straight 

lines."


	


   Your selection of authors for words of guiding wisdom

   have always been a mystery to me. Never have you seemed

   to embrace the notion of simple ideas (obvious profundities)

   and their artful assemblage into useful inventions. Instead,

   your choices seem to frame your writing with pessimistic

   uncertainty if not despair. Buckminster Fuller would be

   disappointed to see you quoting him in this manner. His

   genius and wisdom are beacons of enlightenment and

   discovery for millions. Yet you seem to use this passage

   by Fuller as some rationale for attacking what we do here with

   little demonstrable understanding or willingness of your

   own to teach.



   Had you contacted me directly with this fusillade of

   wild pitches, I would have been inclined to be more

   discrete in our exchange. However, you've elected to show

   us the best you have to offer in open forum carried

   forth with aspersions on my knowledge, skills and integrity.

   Well, it was YOU who picked the time, place and

   weapons sir. I will defend myself and the work that

   honorable and serious students of our science and art

   are doing here.



   Bob . . .



    "There cannot be a greater mistake than that of looking

      superciliously upon practical applications of science.

     The life and soul of science IS its practical application."

                                                                         -Lord 

Kelvin



   Now THAT's what I'm talking about!

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