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1. 10:27 PM - KLX-135A Comm Radio Issue (Gary VanRemortel)
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| Subject: | KLX-135A Comm Radio Issue |
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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