The third digit on my formerly bullet-proof Narco AT-50 transponder has
suddenly started displaying incorrectly for ATC. Specifically, it seems to
be showing as a "4" on their screens, regardless of what we dial it to in
the plane. Thus, instead of squawking "1200" when we're VFR, we're
squawking "1240"...

What could cause this? Any recommendations on repair versus replacement?

Thanks!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

> I've been
> told that manufacturer doesn't allow independent avionics technicians
> to (legally) repair their products anymore for certificated
> installations.

There are no independent avionics technicians. There are certified repair
stations who employ avionics technicians. If the repair station was doing
Narco repairs before Narco pulled the rug out from under all of them and so
still has the correct and current technical data, and some other celestial
bodies align properly, the repair station can still work on the Narco
transponder and return it to service. I know of at least two avionics shops
that can do this if asked, but they don't advertise it, and I think don't
really want to.

The original poster ought to send it back to Narco.

"Jay Honeck" wrote:

> Any recommendations on repair versus replacement?

I can no longer imagine having a transponder with four knobs.

If you get one with sequential digital entry, you can leisurely scoff at all
the Usenet arguments about the dangers of flipping through 7XXX codes...

It's really a minor thing, but I also like the fact that my transponder
displays pressure altitude. When I need to know pressure altitude, it saves
me the trouble of futzing with the Kollsman knob.

Jay, you fly one of the greatest GA airplanes ever designed (except for its
notable lack of a pilot-side door), and it deserves nothing less than the
best.

http://www.garmin.com/products/gtx327/
http://www.bendixking.com/static/catalog/viewproductdetails.jsp?pid=142

"Craig Prouse" wrote:
> If you get one with sequential digital entry, you can leisurely
> scoff at all the Usenet arguments about the dangers of
> flipping through 7XXX codes...
>
> It's really a minor thing, but I also like the fact that my
> transponder displays pressure altitude. When I need
> to know pressure altitude, it saves
> me the trouble of futzing with the Kollsman knob.
>
> Jay, you fly one of the greatest GA airplanes ever
> designed (except for its
> notable lack of a pilot-side door), and it deserves
> nothing less than the best.
>
> http://www.garmin.com/products/gtx327/

Amen. Next to the autopilot, the Garmin 327 is the best thing I've put
in my airplane.
--
Dan
C172RG at BFM

I'm not sure where the Narco repairs are expensive myth started. I've had good
experiences with the Narco factory with everything they've repaired, which
includes a Nav122 on two occasions, an AT150 and a com111B. In each case the
repair bill was very reasonable, and the unit was also updated with all mods and
fully recertified, which usually won't happen with a field repair. The only
beef I had was with turn around time, which is 4-6 weeks unless you pay a
premium for fast turn. IIRC, the premium is about $100, which nearly doubles
the cost of the repairs I had done. They will also evaluate your unit for $90
and let you know what it will cost to repair, and if you do repair it, they
subtract the eval cost from the repair.

The sticking digit sounds like either a switch problem, or a problem with the
digital logic. Where it is not intermittent, it should be easy to find and
fix. I can't imagine that it would be all that expensive to fix, certainly not
the price of a reconditioned unit less the trade in on yours.

Neal wrote:

> On Thu, 04 Sep 2003 03:28:51 GMT, "Jay Honeck"
> > wrote:
>
> >The third digit on my formerly bullet-proof Narco AT-50 transponder has
> >suddenly started displaying incorrectly for ATC. Specifically, it seems to
> >be showing as a "4" on their screens, regardless of what we dial it to in
> >the plane. Thus, instead of squawking "1200" when we're VFR, we're
> >squawking "1240"...
> >
> >What could cause this? Any recommendations on repair versus replacement?
> >
>
> Likely a shorted semiconductor component... either an IC chip, or
> perhaps even something simple as a diode. Given the name brand, you'll
> probably have to send it back to the factory and pay nearly as much as
> a reconditioned unit to replace a faulty $0.25 part in it. I've been
> told that manufacturer doesn't allow independent avionics technicians
> to (legally) repair their products anymore for certificated
> installations.

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

"Dave Butler" wrote:
> I've never used one of the pushbutton units, but I can imagine a
> difficulty with them. With knobs, I can hold on to the knob in
> turbulence while I'm setting the digit. With buttons, I would
> think turbulence would cause you to hit the wrong
> button. Is this just an imaginary difficulty?

The buttons are big enough on the Garmin 327 that it hasn't been a problem
for me, but I've never had to change a squawk in moderate or worse
turbulence.
Still, having used a button xponder, I would never want to go back to the
knob type.
--
Dan
C172RG at BFM

"Ray Andraka" > wrote in message ...
> I'm not sure where the Narco repairs are expensive myth started. I've had good
> experiences with the Narco factory with everything they've repaired, which
> includes a Nav122 on two occasions, an AT150 and a com111B. In

Not my experience with factory service on the Mark 12D+. The factory
price may have been reasonable, but they were slow, unable to provide
loaners in the interim, and the units had to be shipped back multiple times.
Not good on a working aircraft.

"Jay Honeck" > wrote in message
news:Tjy5b.345829$o%2.158911@sccrnsc02...
> The third digit on my formerly bullet-proof Narco AT-50 transponder has
> suddenly started displaying incorrectly for ATC. Specifically, it seems
to
> be showing as a "4" on their screens, regardless of what we dial it to in
> the plane. Thus, instead of squawking "1200" when we're VFR, we're
> squawking "1240"...
>
> What could cause this? Any recommendations on repair versus replacement?
>
> Thanks!
> --

What a coincidence. My AT 150 pulled this stunt at the beginning of a trip
from Texas to Las Vegas about a week ago. In my case, the third digit
flipped back and forth between 5 and 1. The bad news is that it will likely
get worse, to the point where ATC can only see you part of the time. That
caused me to rethink flying into the very busy Las Vegas area, opting
instead to park it at Kingman, AZ. At least we got to see the Hoover Dam
again.

Anyway, the good news is that mine was fixed locally for $65.00. It was
described as being an "adjustment", but I forget what was adjusted. I could
look at the invoice to refresh my memory. While I'd love a pushbutton
Garmin, I'm too cheap to toss a fixable unit.

To save you a phone call, Narco factory service is $95.00 per hour plus
parts. 2 to 3 week turnaround. They have a factory reconditioned exchange
program for $595.00. Also a 2 to 3 week turnaround. I think there are
issues with replacing an AT 50 with a 150. Something about needing a 150R.

Let me know if you want details about where I got mine done.

Dick Meade

Narco also has a 10% off web coupon for service if the radio is sent by the
owner.

In the case of a Nav radio, you could get away with flying without the radio for
a few weeks. A transponder in busy airspace is another thing altogether. Ask
around at the local shops to see if you can find one that will look at it. Here
in the Northeast, I've had good luck with The Radio Shop, which is located at
Worcester Mass, for repairing Narco stuff. Like I said before, the shops will
generally only fix what is wrong; they won't bring the unit up to the latest mod
level, do a complete check on the unit, or warranty the entire unit.

If I was looking at a repair that cost near the value of the transponder, I'd
seriously consider getting a new mode S with plans to eventually connect it to a
MFD for traffic. I don't think I'd spring for a new mode C only at this point,
as I suspect we'll be getting gently nudged to go with mode S in the not to
distant future. Fortunately, yours does not sound like an expensive problem
(the tube is fine, it is the digital encoding that is the problem), just an
inconvenient one. If you are on good terms with a local shop, you might be able
to get a loaner while you send it in to Narco if your local shop can't fix it.

Dick Meade wrote:

> "Jay Honeck" > wrote in message
> news:Tjy5b.345829$o%2.158911@sccrnsc02...
> > The third digit on my formerly bullet-proof Narco AT-50 transponder has
> > suddenly started displaying incorrectly for ATC. Specifically, it seems
> to
> > be showing as a "4" on their screens, regardless of what we dial it to in
> > the plane. Thus, instead of squawking "1200" when we're VFR, we're
> > squawking "1240"...
> >
> > What could cause this? Any recommendations on repair versus replacement?
> >
> > Thanks!
> > --
>
> What a coincidence. My AT 150 pulled this stunt at the beginning of a trip
> from Texas to Las Vegas about a week ago. In my case, the third digit
> flipped back and forth between 5 and 1. The bad news is that it will likely
> get worse, to the point where ATC can only see you part of the time. That
> caused me to rethink flying into the very busy Las Vegas area, opting
> instead to park it at Kingman, AZ. At least we got to see the Hoover Dam
> again.
>
> Anyway, the good news is that mine was fixed locally for $65.00. It was
> described as being an "adjustment", but I forget what was adjusted. I could
> look at the invoice to refresh my memory. While I'd love a pushbutton
> Garmin, I'm too cheap to toss a fixable unit.
>
> To save you a phone call, Narco factory service is $95.00 per hour plus
> parts. 2 to 3 week turnaround. They have a factory reconditioned exchange
> program for $595.00. Also a 2 to 3 week turnaround. I think there are
> issues with replacing an AT 50 with a 150. Something about needing a 150R.
>
> Let me know if you want details about where I got mine done.
>
> Dick Meade

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

Jay Honeck wrote:
>
> What could cause this? Any recommendations on repair versus replacement?

This happened with my Bendix-King unit. My avionics tech fixed it as part of
my 91.413 check - no additional charge. It was a bench repair and took him
only a few minutes.

George Patterson
A friend will help you move. A really good friend will help you move
the body.

Dan Luke wrote:
>
> Still, having used a button xponder, I would never want to go back to the
> knob type.

I know the feeling. I replaced my transponder two years ago. My new one has
knobs; the old one had THUMBWHEEL SWITCHES. I'd never go back!

Aaron Coolidge > writes:

> Jay Honeck > wrote:
> : The third digit on my formerly bullet-proof Narco AT-50 transponder has
> : suddenly started displaying incorrectly for ATC. Specifically, it seems to
> : be showing as a "4" on their screens, regardless of what we dial it to in
> : the plane. Thus, instead of squawking "1200" when we're VFR, we're
> : squawking "1240"...
>
> : What could cause this? Any recommendations on repair versus replacement?
>
> Jay, as others have said you've probably got a problem with the wafer switch
> that the knob actually turns. A decent avionics shop will be able to take
> a wafer switch out of a junk AT50 (oxymoron?) and replace yours.

If Jay owned an experimental airplane, I'd suggest he got some contact
cleaner at Radio Shack, take the xpndr out of the plane, open it, and
spray some cleaner onto the suspect switch, and then go fly test it.

But I can't, since he owns a certificated airplane (which makes him
certifiable).

-jav

> If Jay owned an experimental airplane, I'd suggest he got some contact
> cleaner at Radio Shack, take the xpndr out of the plane, open it, and
> spray some cleaner onto the suspect switch, and then go fly test it.
>
> But I can't, since he owns a certificated airplane (which makes him
> certifiable).

Well, assuming that I install this transponder in my future RV-6 (after
having it professionally repaired this time, of course) and it starts acting
up again, what can I expect to find inside the box?

And is removing it any different than removing one of my NAV/COMs? Is it in
a tray, with slide-in connectors, or do I have to deal with some wiring?

Just curious, for use way in the future. This time it's going to NARCO.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" > wrote in message news:MaO5b.356629$uu5.69298@sccrnsc04...
\
> Just curious, for use way in the future. This time it's going to NARCO.
\
Why on earth woiuld you spend the aggravation sending it to NARCO service.
Take it to whatever avionics shop you like. There ain't anything magic about
the old AT50's. It is most likely a trivial fix. I've had the same thing happen
in planes in the past (spent some time with COS dialing up various numbers
and having them read back what they saw to see what bits were stuck on).

Ron Natalie wrote:

> "Jay Honeck" > wrote in message news:MaO5b.356629$uu5.69298@sccrnsc04...
> \
>
>>Just curious, for use way in the future. This time it's going to NARCO.
>
> \
> Why on earth woiuld you spend the aggravation sending it to NARCO service.
> Take it to whatever avionics shop you like. There ain't anything magic about
> the old AT50's. It is most likely a trivial fix. I've had the same thing happen
> in planes in the past (spent some time with COS dialing up various numbers
> and having them read back what they saw to see what bits were stuck on).
>
>
I've also had very good luck with Narco service.
But, for the price you would pay for a repair, you could probably find a
replacement with a guaranty.
You can find cheap 50's and 50a's for sale all day long!
Just my $0.02


Dave

Ouch, I didn't know that. It's been a few years since I last went to ORH. I also
have had good experiences with Conrad at The Radio Shop with my Narco stuff as
long as it didn't require a part that he didn't have. I was reluctant to
advertise that he did though, as I didn't want to get him in trouble with Narco.
ORH didn't have any landing fee when I was there last. What's with the $48 fee?
It's not like there is that much commercial traffic in and out of there. Is AOPA
on it? They went head to head with Massport over Boston Logan about 10 years ago
over fees.

Aaron Coolidge wrote:

> I know that Conrad at the Radio Shop, in Worcester, MA can fix Narco in-house.
> You'll have to look up his number on airnav, as I can't remember it right
> now. Conrad repaired my AT150 after it smoked in flight, no problems since.
> He had something like a 2-day turnaround. He will accept items UPS to fix
> them (it's more convienient even for me, living 16 miles away, because
> Massport has KORH locked down quite tightly, and gets a $48 landing fee!).
>
> --

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

It's a slide in with a hex drive, same as the comms as I recall. Unfortunately,
the owner maintenance specifically excludes removing and reinstalling the
transponder. However, if it just happened to slide out.... Perhaps if you
tried a "a laying on of hands" (especially if one of those hands had a
screwdriver and then a can of contact cleaner in it) while it was out.... never
mind, book doesn't allow it. Actually, I think the regs don't stop you from
taking it out or even taking it apart. Its the putting it back in without
supervision that will get your wrists slapped.

Jay Honeck wrote:

> > If Jay owned an experimental airplane, I'd suggest he got some contact
> > cleaner at Radio Shack, take the xpndr out of the plane, open it, and
> > spray some cleaner onto the suspect switch, and then go fly test it.
> >
> > But I can't, since he owns a certificated airplane (which makes him
> > certifiable).
>
> Well, assuming that I install this transponder in my future RV-6 (after
> having it professionally repaired this time, of course) and it starts acting
> up again, what can I expect to find inside the box?
>
> And is removing it any different than removing one of my NAV/COMs? Is it in
> a tray, with slide-in connectors, or do I have to deal with some wiring?
>
> Just curious, for use way in the future. This time it's going to NARCO.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

"Jay Honeck" > writes:

> > If Jay owned an experimental airplane, I'd suggest he got some contact
> > cleaner at Radio Shack, take the xpndr out of the plane, open it, and
> > spray some cleaner onto the suspect switch, and then go fly test it.
> >
> > But I can't, since he owns a certificated airplane (which makes him
> > certifiable).
>
> Well, assuming that I install this transponder in my future RV-6 (after
> having it professionally repaired this time, of course) and it starts acting
> up again, what can I expect to find inside the box?

Little black boxes with smoke inside. DO NOT LET THE SMOKE OUT.

> And is removing it any different than removing one of my NAV/COMs? Is it in
> a tray, with slide-in connectors, or do I have to deal with some wiring?

Same deal, same hex key.

> Just curious, for use way in the future. This time it's going to NARCO.

Er, OK.

-jav

I tried to hint at that, but you won't get me to admit that I had done it. Make sure
the contact cleaner you use doesn't have oil in it. Some of the readily available
consumer brands have oil and a perfume in them.

Newps wrote:

> You guys worry like old women. Take the damn thing out, spray whatever
> you want in there and put it back in. Repeat until fixed.
>
> Ray Andraka wrote:
> > It's a slide in with a hex drive, same as the comms as I recall. Unfortunately,
> > the owner maintenance specifically excludes removing and reinstalling the
> > transponder. However, if it just happened to slide out.... Perhaps if you
> > tried a "a laying on of hands" (especially if one of those hands had a
> > screwdriver and then a can of contact cleaner in it) while it was out.... never
> > mind, book doesn't allow it. Actually, I think the regs don't stop you from
> > taking it out or even taking it apart. Its the putting it back in without
> > supervision that will get your wrists slapped.
> >

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

Ray Andraka wrote:
> I tried to hint at that, but you won't get me to admit that I had done it. Make sure
> the contact cleaner you use doesn't have oil in it. Some of the readily available
> consumer brands have oil and a perfume in them.

I do it all the time. Sometimes I'll do it with my mechanic, sometimes
he will tell me the procedure over the phone. Whatever. Can't believe
anybody would worry about sliding a radio in and out.

> > Just curious, for use way in the future. This time it's going to
NARCO.
>
> Er, OK.

Yes. It's going to Narco this time. Naturally. Of course...

:-)

Thanks, Jav!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Newps" > wrote in message news:7UP5b.268278$Oz4.70312@rwcrnsc54...
> You guys worry like old women. Take the damn thing out, spray whatever
> you want in there and put it back in. Repeat until fixed.
>
It must be connected to the landing light if you follow the wires far enough :-)

Ray Andraka > wrote:

Ray, supposedly the $48 is only for twin engine and larger A/C. That includes
privately owned twins. It's a security, ramp, and langing fee. A couple of
folks I know have been in there in singles and have been requested to pay
the fee, and they refused. If one didn't know that the fee was aimed at
twins only, and one was asked to pay the fee, probably some would.

When I went in there last month to look at an airplane at the dealer's, I
hid from the fbo so that I wouldn't get hit up for the fee, or required to
rent a prop lock (which is required at all massport fields, I believe).
Worked well, and the dealer said that many folks do the same.

--
Aaron Coolidge (N9376J)