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Strobes not working

A

Andreas68

Member
None of my three strobes (two wingtip strobes; rudder strobe) are working. The rudder static position light does work. Its a Whelen system. Have heard of other pilots frying their wingtip strobe tubes/bulbs because of heat issues under the plexiglass but the power supply seems the most likely culprit if all three strobes are out. Other ideas? I tried PMing RocketBob about how he fixed his Whelen Power supply with a 50 cent capacitor but his mailbox was full. If you see this, RocketBob, would appreciate insight on how you completed this repair. Not eager to spend $674 on a new Whelen Power supply when I don't fly at night.
Thanks for any info
Andreas
RV7A
 
I opened the box up, checked the large caps with a capacitor tester, and replaced the cap that was bad.
 
I opened the box up, checked the large caps with a capacitor tester, and replaced the cap that was bad.

Be very careful when handling the power supply as the capacitor voltages can be lethal!
 
rocketbob said:
To be quite honest I've changed more LED strobes out in the past two years than the old kind. In every case the LED's were non-repairable due to the circuit boards being potted.
Click to expand...

Luckily, the FlyLEDs components are not potted... Parts would be easily swapped out, if needed.

Plus, the customer support is excellent. Had a strobe that didn't quite want to work properly going into Osh last year. Paul has gracious enough to not only replace the controller board completely, he assembled it for me so I could make the repair before departing.
 
Strobes not Working, switch is fried

Thanks very much for the helpful advice. Here's an update:
I crawled under the panel and checked the fuses and wiring to/from the Strobe light switch (BTW, I didn't build the airplane so the switch wiring and harness wiring is a bit confusing to say the least). The strobe switch connector wire to the Whelen Power Supply has partially melted: the insulation melted and pooled into a glob around the connector. It appears to be a case of thin (white) wire coming into the switch from airplane power (battery) and a thicker (red) wire going to the Whelen Power supply - a mismatch in wire gauge leading to overheating at the switch. It's the red wire that's burned outgoing from the switch to the Whelen PS. There's also a 10 amp (red) fuse that's blown but I'm not sure what it powers since there are no labels and I can't follow the individual wires to the fuse box because there are too many of them and they're all white. It might be the strobe fuse or not. In terms of solutions to prevent future problems with overheating at the switch, I could replace the thin white (power) wire with a thicker one which would require digging into the wire harness and be a pain because, as you know, you have to invert or contort yourself to redo wiring under/behind the panel. Or maybe install a relay between the switch and the Whelen power supply to serve as a voltage regulator/circuit "policeman." Any comments/advice appreciated since I have a limited understanding of electrical circuits.
 
Strobes not Working, switch is fried

Thanks very much for the helpful advice. Here's an update:
I crawled under the panel and checked the fuses and wiring to/from the Strobe light switch (BTW, I didn't build the airplane so the switch wiring and harness wiring is a bit confusing, if not a mystery, to say the least). The strobe toggle switch connector wire to the Whelen Power Supply has partially melted: the insulation melted and pooled into a glob around the connector. The now bare copper wire is greenish in tint. It appears to be a case of thin (white) wire coming into the switch from airplane power (battery) and a thicker (red) wire going to the Whelen Power supply - a mismatch in wire gauge leading to overheating at the switch. It's the red wire that's burned outgoing from the switch to the Whelen PS. There's also a 10 amp (red) blade fuse that's blown but I'm not sure what it powers since there are no labels and I can't follow the individual wires to the fuse box because there are too many wires and they're all white. It might be the strobe fuse or not. In terms of solutions to prevent future problems with overheating at the switch, I could replace the thin white (power) wire with a thicker one which would require digging into the wire harness and be a pain because, as you know, you have to invert or contort yourself to redo wiring under/behind the panel. Or maybe install a relay between the switch and the Whelen power supply to serve as a voltage regulator/circuit "policeman." Any comments/advice appreciated since I have a limited understanding of electrical circuits.
 
Given that the thicker wire melted, right at the switch, it seems most likely that the switch contacts failed in a moderate resistance fashion, leading to high temperatures which had no where to go but out the wires.
To track down the fuse, put an ohmmeter probe on one end of the fuse (try the other end, too, if the fuse is still blown) and the other ohmmeter probe back on the strobe switch (switch on, master power off). Very low resistance, and you know that fuse is hooked to that switch.
 
Photo of the switch, front and back, and the wires would help.
Don?t be afraid of digging into the harness. The relay idea is just making things more complicated.
Snipping some wire ties to open up the harness, and maybe doing some labeling will help in the future. You might find some other marginal circuits too.
 
Couple things to try

Andreas68 said:
Thanks very much for the helpful advice. Here's an update:
I crawled under the panel and checked the fuses and wiring to/from the Strobe light switch (BTW, I didn't build the airplane so the switch wiring and harness wiring is a bit confusing, if not a mystery, to say the least). The strobe toggle switch connector wire to the Whelen Power Supply has partially melted: the insulation melted and pooled into a glob around the connector. The now bare copper wire is greenish in tint. It appears to be a case of thin (white) wire coming into the switch from airplane power (battery) and a thicker (red) wire going to the Whelen Power supply - a mismatch in wire gauge leading to overheating at the switch. It's the red wire that's burned outgoing from the switch to the Whelen PS. There's also a 10 amp (red) blade fuse that's blown but I'm not sure what it powers since there are no labels and I can't follow the individual wires to the fuse box because there are too many wires and they're all white. It might be the strobe fuse or not. In terms of solutions to prevent future problems with overheating at the switch, I could replace the thin white (power) wire with a thicker one which would require digging into the wire harness and be a pain because, as you know, you have to invert or contort yourself to redo wiring under/behind the panel. Or maybe install a relay between the switch and the Whelen power supply to serve as a voltage regulator/circuit "policeman." Any comments/advice appreciated since I have a limited understanding of electrical circuits.
Click to expand...

I am sure someone with more professional experience wiring will eventually chime in but there are a couple things to check:

First, with the master and strobe switches OFF, check the continuity (with a multimeter) between the load side of the blown fuse and the pole on the strobe switch with the white wire. Assuming you get the beep indicating continuity you know the blown fuse is for the strobes.

2nd, if the red wire is melted then it is almost certainly the problem one. Since the Mil-Spec Tefzel wire normally used is tinned copper, the red wire is probably just Hardware/auto wire. The green tint on the copper wire is corrosion (the mil-spec wire is tinned specifically to prevent corrosion). It’s possible the corrosion developed after the strobes failed but my guess would be the corrosion caused the failure. Corrosion dramatically increases the resistance in that part of the wire, which would explain why the insulation was melted right there and why the fuse blew.

If there is any excess red wire it MIGHT be possible to cut the corroded bit of the red wire off, strip a bit more insulation off, tin the bare wire and reattach it to the switch. However, I would only do that if someone here with professional electrical experience (which I don’t have:D) said it would work long term.

If it were me, I would use the existing red wire to pull a mil-spec m22759/16 16 gauge wire from the switch to the strobe power box. 16 gauge is more than enough for a 10A fuse and 10 ft will cost about $5 from any of the vendors selling wire who advertise here.
 
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Does the switch have Faston (1/4") terminals for the wires? And are the Faston terminals held on the switch by rivets? If both answers are 'yes', it's likely it's a switch either sold by B&C Specialty, or the same brand sold by someone else. They are quality switches, even in moderately high current applications.
But. (The following has been hashed out on the Aeroelectric Connection email list.)
There have been a significant number of cases where the apparently extreme current pulses from old-school strobe supplies have overstressed the switch. The result looks like what you described. Fix is a higher current switch, or use the new switch to control a relay for switching the strobes.

Don't know if that is your only problem, but it might well be one of them.

Charlie
 
A bad connection will drop voltage. A voltage drop can cause a switching power supply to draw more current. Increased current will cause the bad connection to get even hotter. Replace the switch and wire terminals.
 
Thanks for the valuable advice. Not sure how to attach a photo of the burnt wire/switch. Apparently I don't have permission to add attachments. But will request it from the webmaster (if someone else has to approve, please advise who that is).

Summarizing the above posts, it appears one or more of the following options might resolve the strobe switch overheating issue: 1) address the corrosion issue (the green tint on the exposed copper wiring of the red wire going from the strobe switch to the Whelen power supply) by replacing the wire with MIl-Spec Tefzel 16 gauge; 2) replace the switch with a higher current capable switch (if you have a source for these switches please advise and what current I should select); 3) divided opinions on the relay (when I got new fuses at AutoZone two mechanics there swore a relay would do the trick but they work on cars not airplanes, and I certainly don't want to make this more complicated than it is by adding a relay to the circuit if it doesn't add value.
 
Nobody can attach a picture on VansAirforce. Any picture that you see is posted on some other website. A link to the picture is posted on VansAirforce using the yellow picture icon.
 
Andreas68 said:
Thanks very much for the helpful advice. Here's an update:
I crawled under the panel and checked the fuses and wiring to/from the Strobe light switch (BTW, I didn't build the airplane so the switch wiring and harness wiring is a bit confusing to say the least). The strobe switch connector wire to the Whelen Power Supply has partially melted: the insulation melted and pooled into a glob around the connector. It appears to be a case of thin (white) wire coming into the switch from airplane power (battery) and a thicker (red) wire going to the Whelen Power supply - a mismatch in wire gauge leading to overheating at the switch. It's the red wire that's burned outgoing from the switch to the Whelen PS. There's also a 10 amp (red) fuse that's blown but I'm not sure what it powers since there are no labels and I can't follow the individual wires to the fuse box because there are too many of them and they're all white. It might be the strobe fuse or not. In terms of solutions to prevent future problems with overheating at the switch, I could replace the thin white (power) wire with a thicker one which would require digging into the wire harness and be a pain because, as you know, you have to invert or contort yourself to redo wiring under/behind the panel. Or maybe install a relay between the switch and the Whelen power supply to serve as a voltage regulator/circuit "policeman." Any comments/advice appreciated since I have a limited understanding of electrical circuits.
Click to expand...

If the wire between the switch and strobe unit melted, the problem is not the switch, it downstream of the melted portion. If the switch were the problem, it would have melted or melted the wire upstream of the switch or both and the red wire would have been left unscathed. It would seem that the white wire is either a larger gauge than the red onw or has a different type of insulation. Are both Tefzel? thick insulation is usually PVC, which will melt at a lower temp than tefzel.

Larry
 
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