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garyvanremortel(at)gmail.
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 Posted: Mon Apr 22, 2024 9:27 pm Post subject: KLX-135A Comm Radio Issue |
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Just a report from the field regarding aging avionics devices with electrolytic capacitors.
Like many of you early builders, I installed the Bendix king KLX-135A panel mount GPS/Comm when I built my RV-6A S/N 22665 in the mid to late '90s. Electrolytic capacitors have a finite life of somewhere between 20 and 30yrs regardless of hours of operation. Over the years the unit had performed well, having just the need for a replacement Tadiran battery on the Digital Board, new LCD and replacement of the optical sensors on freq selector.
Yesterday the unit died on the taxiway, accompanied by the pungent toasted fish smell of a fried electrolytic capacitor. I bought the entire operation and maintenance binder for the unit many years ago off Ebay, so have all the service info, parts lists, assembly drawings and schematics. Upon disassy C1 (47uF 50V) on the Power Supply Assy had exploded, leaving a fried hole nearly all the way thru the PCB and dielectric everywhere. It had clearly shorted. C1 is the power filter on the DC input power line so it charges up every time power is cycled ON. I repaired the PCB with epoxy and reinstalled a better capacitor with higher voltage rating. The shorting of C1 on the Power Supply PCB took out the axial leaded fuse F1 on the comm/receiver PCB and these are readily available from Amazon for about $1 apiece (Littelfuse 251007 https://www.amazon.com/dp/B00LQSF6NQ?psc=1&ref=ppx_yo2ov_dt_b_product_details )
It may be wise to inspect your unit if yours is as old as mine is. Blue skies.
-GV
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rv8iator
Joined: 11 Apr 2006
Posts: 144
Location: Newberg, OR
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| Posted: Tue Apr 23, 2024 5:25 am Post subject: KLX-135A Comm Radio Issue |
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I've had a similar experience with failing electrolytic aluminum can caps. Interesting in that all the failures have been in aluminum radial leaded caps. Never have had a failure of axial leaded. Also the failures were in power circuits and the voltage rating was near the working voltage. Nominal circuit voltage of 14 volts used a 25 volt part. Thanks for your post, another good data point.
Chris
RV-8 x 2, Long EZ
On Mon, Apr 22, 2024 at 10:32 PM Gary VanRemortel <garyvanremortel(at)gmail.com (garyvanremortel(at)gmail.com)> wrote:
| Quote: | Just a report from the field regarding aging avionics devices with electrolytic capacitors.
Like many of you early builders, I installed the Bendix king KLX-135A panel mount GPS/Comm when I built my RV-6A S/N 22665 in the mid to late '90s. Electrolytic capacitors have a finite life of somewhere between 20 and 30yrs regardless of hours of operation. Over the years the unit had performed well, having just the need for a replacement Tadiran battery on the Digital Board, new LCD and replacement of the optical sensors on freq selector.
Yesterday the unit died on the taxiway, accompanied by the pungent toasted fish smell of a fried electrolytic capacitor. I bought the entire operation and maintenance binder for the unit many years ago off Ebay, so have all the service info, parts lists, assembly drawings and schematics. Upon disassy C1 (47uF 50V) on the Power Supply Assy had exploded, leaving a fried hole nearly all the way thru the PCB and dielectric everywhere. It had clearly shorted. C1 is the power filter on the DC input power line so it charges up every time power is cycled ON. I repaired the PCB with epoxy and reinstalled a better capacitor with higher voltage rating. The shorting of C1 on the Power Supply PCB took out the axial leaded fuse F1 on the comm/receiver PCB and these are readily available from Amazon for about $1 apiece (Littelfuse 251007 https://www.amazon.com/dp/B00LQSF6NQ?psc=1&ref=ppx_yo2ov_dt_b_product_details )
It may be wise to inspect your unit if yours is as old as mine is. Blue skies.
-GV
|
| | - The Matronics RV-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?RV-List |
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C. Stone (RV8iator) |
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