Stall warning failure

How to keep the Cessna 170 flying and airworthy.

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Bruce Fenstermacher
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Re: Stall warning failure

Post by Bruce Fenstermacher »

WOOPS,

After a restfull sleep it it occurred to me that the Lionel horns I listed DON'T work of 12 to 20vdc. The solenoid that activates the horn works on 12-20vdc. The horn itself is powered by a single D battery (1.5vdc) and it is this battery that leaked and destroyed so many engines. How quickly I forget.

Doesn't mean the Lionel horns won't work on 12vdc, I've never tried it or you could use a dropping resister inline with the horn.

Mark, if you tell me it would physically fit I'll investigate further.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
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Bruce Fenstermacher
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Re: Stall warning failure

Post by Bruce Fenstermacher »

This from a Lionel train site about how to "fix" these horns. I've never found a train horn I couldn't revive but I guess it can happen.
5. Often the sound can be restored by fiddling with the adjusting screw on the back of the horn. Slowly turn the adjusting screw in both directions until the horn diaphragm is in the right position to make the unit squawk when power is applied. Sometimes, just sitting in one position for 30 or 40 years will distend the diaphragm enough to need re-adjustment. Patience here. Slowly turn the adjusting screw all the way in both directions several times before you give up.

6. If you get any kind of noise at all, the adjustment then becomes one of fine-tuning until the maximum sound is produced. This is a critical point. Turn the screw carefully and take your time. You might not hear the "Kee-Onk, KeeOnk" of the mighty Hiawatha - it might sound more like the sickly "Oink-Oink" of an undernourished pig - but that's about the best you can expect from an old Lionel horn unit. Even when new, their sound probably resembled the barnyard more than the railroad yard, but you might not remember it that way. Kids tend to listen with their imaginations rather than their ears!

The Lionel service manuals recommend replacement of inoperative or faulty horns. No procedure for taking them apart was ever published.

Although some service station technicians did take them apart in the days before new replacements were again available from after-market sources, the results were, at best, uneven. Sometimes the damaged internal coil and linkages could be repaired, but most often not.

I've never had much luck just taking them apart. The two-part horn cases are crimped tightly together by machine, so it is almost impossible to disassemble them without breaking off the little crimping "fingers" in the process. Of course, when that happens, the unit is junk.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
CAVU Mark
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Joined: Sat May 09, 2009 5:42 am

Re: Stall warning failure

Post by CAVU Mark »

Thanks Bruce. Yes, the little fingers on the horn are starting to break so I think I will try a few of George's suggestions. The ID of the housing is too small for the Lionel horn. I did find an interesting horn that also includes a USB port for downloading a sound file that plays when triggered. So I could get a friendly voice to repeat "Warning Will Rogers, Warning".
Mark
russfarris
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Re: Stall warning failure

Post by russfarris »

CAVU Mark wrote:Thanks Bruce. Yes, the little fingers on the horn are starting to break so I think I will try a few of George's suggestions. The ID of the housing is too small for the Lionel horn. I did find an interesting horn that also includes a USB port for downloading a sound file that plays when triggered. So I could get a friendly voice to repeat "Warning Will Rogers, Warning".
"Warning Will Rogers, Warning".[/quote]

I think you mean Will Robinson. I can't get the image of The Robot and humorist Will Rogers on an unknown planet "Lost In Space" out of my head now!

Russ Farris
All glory is fleeting...
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n2582d
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Re: Stall warning failure

Post by n2582d »

CAVU Mark wrote:... I did find an interesting horn that also includes a USB port for downloading a sound file that plays when triggered. So I could get a friendly voice to repeat "Warning Will Rogers, Warning".
"Friendly voice"? Nah, you need "Bitching Betty" to scream "DUMMY, LOWER THE NOSE!!!!"
Gary
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ghostflyer
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Re: Stall warning failure

Post by ghostflyer »

we had imported a Piper aircraft into the country [australia]and was reassembling it when the stall warning system wouldnt work. We thought the horn was u/s. But it worked when directly conected to a battery but not fitted to the aircraft. Contacted Piper with the right part number ,not available for 4 weeks plus $400 price tag. So I sent a employee down to Tandy to get a similar one to test the the circuit. He came back with a smile on his face and threw me the new one. It cost a little over $6. It was exactly the same horn INCLUDING the manufacturers part number stamped on the outer case. It was in a Tandy clear plastic case. The stall warning on this aircraft works just fine after 3 years and over 1400 hrs of flying.
CAVU Mark
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Re: Stall warning failure

Post by CAVU Mark »

Yes, Will Robinson... I knew something didn't feel right about that when I wrote it. Anyway DigiKey has more buzzers that Heinz has pickles and that is where I bought mine.

Here is the USB programmable unit for those preferring the voice warning, "Danger Will Robinson". $15 buckeroos.
http://www.mcmelectronics.com/product/P ... R-/50-2992

MODerators Note: We have been notified that “link” is no longer valid, and we are offered a link to an online article explaining the demise of the company which we do not believe germane to our purposes, however if anyone should desire to see the article here is the link...at your own risk. https://www.icrfq.com/blog/what-happene ... onics.html
Mark
rusbac
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Re: Stall warning failure

Post by rusbac »

Sorry to revive an old thread. Here are some photos of the inside of the stall warning instrument, for future reference.
SM Horn 3.jpg
SM Horn 2.jpg
My horn stopped buzzing but the warning light still works properly.
It appears the power wire leading into the buzzer component was touching the metal case of the buzzer and causing a short.
Christine in Boston
N2481D - '52 170B
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GAHorn
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Re: Stall warning failure

Post by GAHorn »

Christine, if you can repair yours...that's great.
If you need a new buzzer capsule... contact me.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
rusbac
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Re: Stall warning failure

Post by rusbac »

Thanks George,

I was able to fix mine and re-install it. With a foot of snow on the ground and another foot expected in the next 24 hrs, I'm happy to be getting something (anything) done this weekend. Suddenly all the Cessnas on the ramp have turned into tailwheels like mine. :lol:
gahorn wrote:Christine, if you can repair yours...that's great.
If you need a new buzzer capsule... contact me.
Christine in Boston
N2481D - '52 170B
dkmp215
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Re: Stall warning failure

Post by dkmp215 »

Here is an update to the price estimate George supplied on 15 October 2009.
My Safe Flight type R 'buzzer' (like the one in the photos above) recently quit working - the estimate I was provided for overhaul was $1759 USD (and $267 to return it to me unrepaired). I declined and installed a different 'high pitched sound maker'. I do prefer the obnoxious sound of the Safe Flight unit, but at >5 percent of my airplane's value, I found it unaffordable.
I, too, will have to join the group of people looking for cheaper alternatives on ebay.
Dave P.
Dave Patterson
C-GFYQ - 1948 C170 S/N 18694
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GAHorn
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Re: Stall warning failure

Post by GAHorn »

If the buzzer is inoperative...and you are CERTAIN it's the buzz unit.... contact me for a solution by PM or email.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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rydfly
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Re: Stall warning failure

Post by rydfly »

Hi folks, I'm reviving an old thread here...

To confirm, if I probe for voltage at EITHER post on the rear of the buzzer unit with the master switch ON, I should see about 12 volts, yes? I'm currently getting voltage from only one post, which makes me think there's likely a short within the buzzer.

Does this logic hold true?

Thanks,

-Kennet
1953 C170B - N170RP S/N 25865
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n2582d
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Re: Stall warning failure

Post by n2582d »

Kennet,
You're correct in thinking that when you have power from the bus and the stall warning vane switch open you should see around 12 volts on either post of the buzzer if it is operating correctly. But if the buzzer is shorted internally you will also have voltage at both posts. Them electrons will go directly from wire 79 to wire 80 as illustrated below. If the buzzer is shorted to ground it should blow the 2 amp. fuse resulting in no voltage to the entire circuit on that fuse. I don't see how it could short to ground though - the buzzer and light are totally insulated in the polyoxybenzylmethylenglycolanhydride (otherwise known as Bakelite) case. If you have an open circuit in the buzzer and light you'll only register voltage on the post going to the bus.
IMG_0390.JPG
Gary
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rydfly
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Re: Stall warning failure

Post by rydfly »

Thank you, Gary. An "open" within the buzzer/light assembly sounds like the likely culprit. I'll have to pull it all out to know for sure.

Unfortunately, it's a somewhat challenging task as my shock panel isn't original and completely covers my stall warning buzzer. I may have to pull the whole panel off just to reach the four screws holding it in place.

If I need to repair/rebuild the buzzer. Any idea how loud (dB) a replacement ought to be?
1953 C170B - N170RP S/N 25865
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