---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 09/10/10: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:09 AM - Re: strobe power supply wiring issues (John Ciolino) 2. 06:09 AM - Exp Bus with Jab 3300 (ple190) 3. 09:22 AM - Re: strobe power supply wiring issues (Robert L. Nuckolls, III) 4. 09:36 AM - Re: strobe power supply wiring issues (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 05:09:04 AM PST US From: "John Ciolino" Subject: Re: AeroElectric-List: strobe power supply wiring issues Chris, I had a somewhat similar problem in my strobe switch, It felt very hot to the touch although it did not burn the terminal or wire. I took things apart and I found that it was the wire teriminal that was getting hot (and making the wire and switch hot). The push on connector felt tight on the tab, but at the suggestion of our local tech advisor, I squeezed the tab, forced on the connector (it was really tight now) and my problem was solved. Something to look into to. John Ciolino RV-8 N9394Y ----- Original Message ----- From: "Chris Hand" Sent: Thursday, September 09, 2010 2:51 PM Subject: AeroElectric-List: strobe power supply wiring issues > I've had some problems with my strobe power supply and/or wiring that I > haven't quite been able to figure out. Looking to see if any of you have > seen something similar or have any advice on next steps. Whelen tech > support has been very helpful and is telling me the power supply checks > out > fine at the factory (ran it on their tester for 2 hrs with no problems) so > I > believe the issue has to be in the connectors or wiring. > > Here's the history: > > Whelen A413A power supply firing strobes in wingtip A600 fixtures. > Installed, tested, and worked fine until strobes quit firing at about 50 > hrs > total flight time (I run the strobes whenever the engine is running, > except > for on ground at night and I don't fly at night much). I used 18AWG wire > for the main power and ground runs, per installation instructions. Power > supply is installed on floor just behind baggage compartment of my RV-6A. > Wiring length and guage meets requirements for expected current draw. > > On initial failure at approx 50 hrs, I found the ground return wire for > main > power plug to power supply to have overheated, melting the wire and > connector where my aircraft wiring met the factory harness pigtail (see > attached photos with "50hrs" in file name). > >>From the looks of the overheated connector for ground return wire, I >>assumed > I had inadvertently cut wire strands when stripping insulation for > connector > installation, leaving not enough wire guage to carry the expected 7A > current, thus overheated the connector. So I removed the damaged wire, > replaced connector with same style (being very careful not to damage wire > strands and to get a good crimp), and tested strobes with no issues. > > Everything worked fine until strobes quit firing again at about 150 hrs > total time (approx 100 hrs since first issue). > > On inspection after the second failure, I found the same connector/crimp > to > have visible heat damage but not to the extent of melting to an open like > I > had the first time. The resistance across this heat damaged connector was > about 0.8 ohms, but not open (measured after cutting wires on either side > of the connector without disconnecting the spade terminals). See > attached > pictures with "150hrs" in file name for what it looked like this second > time > around. > > I installed a pin/socket style AMP connector for the power and ground vice > the PIDG style connector, verified I had 12V power at the pin going into > the > power supply, and verified the ground wire pin had continuity to airframe > ground (the ground return wire is connected to firewall common ground > point > and appears good). But when plugged into the strobe power supply, the > power > supply wouldn't fire the strobes - no charge/discharge noise and no strobe > lights. > > Based on the above, I assumed the power supply must be bad and sent it to > Whelen factory repair after calling them. They said the power supply > checks > out good and the connectors on the power supply look good. They are > sending > it back to me with a new main power connector harness. > So, I'll reinstall when I get it back and see if I can get it to work, but > I'm still at a loss as to what went wrong with the two failures and why it > wouldn't work when I tried the AMP style connector. > > I thought about trying to just ground the power supply locally, but the > installation instructions state not to do this and I don't want to make a > change that may result in strobe noise in my avionics systems. My current > installation (when strobes are working) doesn't have any strobe noise in > any > of my audio/avionics systems. Grounding locally also wouldn't resolve > root > cause on this since the ground return and connector should have been able > to > handle the expected current load. > > Some other pictures of power supply wiring runs and installation are at: > http://rv6aproject.ckhand.com/panelAndElectrical/electrical/electricalPg6.htm > and 3rd picture down on this page: > http://rv6aproject.ckhand.com/panelAndElectrical/electrical/electricalPg8.htm#photo3 > Any ideas, or something I might be missing? Thanks, ChrisRV-6A, N731CK ________________________________ Message 2 _____________________________________ Time: 06:09:49 AM PST US Subject: AeroElectric-List: Exp Bus with Jab 3300 From: "ple190" Any one have a diagram for the alternator/regulator wiring for this combo. Which wire connects to the Alt Field switch ? Also is there any point using a B&C over voltage protection kit as the exp bus has a built in OV cutoff ? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=312018#312018 ________________________________ Message 3 _____________________________________ Time: 09:22:29 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: strobe power supply wiring issues At 07:04 AM 9/10/2010, you wrote: Chris, I had a somewhat similar problem in my strobe switch, It felt very hot to the touch although it did not burn the terminal or wire. I took things apart and I found that it was the wire teriminal that was getting hot (and making the wire and switch hot). The push on connector felt tight on the tab, but at the suggestion of our local tech advisor, I squeezed the tab, forced on the connector (it was really tight now) and my problem was solved. What brand of fast-on terminals are you using? Something to look into to. Many List members will recall some discussions we had a couple years ago about switch failures . . . http://tinyurl.com/2a2qqp Go to the http://matronics.com/search and check the AeroElectric archives for carling switch failures from the time a wire approaches one of these switches until it winds its way off to new adventures there's a substantial string of metal-to-metal joints in series with the current flow. (1) wire to terminal grip (2) fast-on grip to fast-on tab (3) fast-on-tab to rivet head (4) Rivet to saddle (5) saddle to rocker (6) rocker to contact (7) contact to contact rivet (8) contact rivet to fast-on tab (9) fast-on grip to fast-on tab (10) wire to terminal grip In the case of Carlings, the most mechanically fragile are 3, 4, and 8 because clamp- up forces on the joints come against plastic housings. The most environmentally fragile are 5 and 7 because they cannot strive for gas tightness. Unfortunately, there are stresses on the gas-tight interfaces that can degrade the joint including process (wrong tool or inadequate workmanship), materials (poor choice of alloys, plating, etc), environment vibration opens joints, moisture gets in, etc) and even perhaps design (rare). Once any of these joints is compromised, it's resistance goes up, electron flow and physical heating combined with moisture and oxygen promote corrosion which further degrades mechanical and electrical integrity of the joint. It's a slay-ride down a steep hill after that. The most demanding circuit in the airplane is strobes. 5-7 amps, continuous duty for duration of flight. When these failures are observed, there IS an explanation that is rooted in failure to maintain very low ohmic contact between all the pieces and parts. Failures can begin in any one or any one or combination of the ten joints cited above. Failures cited at the initial posting of this thread have one-for-one commonality with failures and probable causes explored in the discussion on switch failures last year. Bob . . . ________________________________ Message 4 _____________________________________ Time: 09:36:04 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: strobe power supply wiring issues At 12:42 AM 9/10/2010, you wrote: Thanks Bob, I'll try a different connector type when I get the power supply back from Whelen. I do still have the second carcass (the less damaged one from 150 hr point) and it's possible I might have the original melted one if I didn't lose or toss it when I moved my plane and hangar contents to a different airport a few months back (E16 to KRHV move in San Jose, CA area). I didn't cut the crimp area to look at cross-section but the fast-on tabs looked normal and the grip strength was good when I seperated the male and female sides after checking resistance across the connector. I'd be happy to send you the carcass I have, or both if I can find the first one, if you're interested in examining the crimps and connector. Yes, I'd like to do that. Localized heating as demonstrated by color of the insulation tells us the failure was loss of gas-tightness in that area. We only need to deduce root cause. The crimp tool I used was a ratcheting AMP ProCrimper I bought from Chief Aircraft prior to starting the electrical system. I used it throughout construction and have had no problems with any other connectors. But are the fast-on terminals also made by AMP? The total bulk of insulator, sleeve, terminal material and strands of wire controls how much pressure the tool brings to bear on the joint. If you have more of the same terminals, crimp a couple of terminals onto a scrap of the same wire and send that too. My error may have been the Home Depot / Fry's connector source but I haven't seen anything obvious on these two particular crimps/connectors that would lead me to believe they shouldn't have been able to handle the expected 7A load. Oops . . . current doesn't have much to do with joint failure . . . only the RATE of degradation once gas-tightness is lost. These kinds of failures DID NOT initiate in the few hours preceding events that brought the failures to your attention. Inadequate installation or improper mating of parts, materials and tools may have given you incipient failures that started marching off toward overt failure in the first hours of flight. One problem I've seen on fast-on terminals with indeterminate pedigree is the alloy. Some copper alloys are NOT capable of sustained mating forces over time, vibration, temperature cycles. Assuming Whelen is correct that the power supply is operating properly then clearly in both the 50 hr and 150 hr failure, that one single crimp was inadequate, at least over time, resulting in significant overheating. I just don't understand why yet. Let's see if we can figure it out. I'll let you know when I get it hooked up and tested again. I appreciate your feedback. My pleasure . . . Bob . . . ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.