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Dancing Ammeter

 
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egilroy(at)gmail.com
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PostPosted: Sun Aug 31, 2008 2:22 pm    Post subject: Dancing Ammeter Reply with quote
Hello:

Been a member for a few weeks now, trying to figure out a problem on a club 172 (building a RV-Cool.

The term "dancing" seems to be applied to what is happening. With light load on (no landing/taxi lights, pitot heat, etc) the ammeter makes a rhythmic swing around the zero point of the meter. I would guess 60-80 times per second. This started a year ago and our A+P says no big deal, at least 3 ships at our airport have the same problem!!! With a heavy, full load (turn everything on), ammeter firms right up.

I had a nasty alternator/battery failure last november inside the NYC VFR corridor (no place to lose your comm!!!) and replaced alternator + regulator but this problem stills haunts us. We recently swapped the regulator with another, no joy.

Ideas on how to proceed?

Thanks... Ed

[quote][b]

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nuckolls.bob(at)cox.net
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PostPosted: Sun Aug 31, 2008 5:25 pm    Post subject: Dancing Ammeter Reply with quote
At 06:20 PM 8/31/2008 -0400, you wrote:
Quote:
Hello:

Been a member for a few weeks now, trying to figure out a problem on a
club 172 (building a RV-Cool.

The term "dancing" seems to be applied to what is happening. With
light load on (no landing/taxi lights, pitot heat, etc) the ammeter makes
a rhythmic swing around the zero point of the meter. I would guess 60-80
times per second. This started a year ago and our A+P says no big deal,
at least 3 ships at our airport have the same problem!!! With a heavy,
full load (turn everything on), ammeter firms right up.

I had a nasty alternator/battery failure last november inside the NYC
VFR corridor (no place to lose your comm!!!) and replaced alternator +
regulator but this problem stills haunts us. We recently swapped the
regulator with another, no joy.

Ideas on how to proceed?


See list-server thread at:

http://tinyurl.com/6fb32p

also top of column 2 on the last page of:

http://www.aeroelectric.com/Mfgr_Data/Regulators/Zeftronics/R15V00_Ford_Style_Reulator.pdf

and column 2, third paragraph, page 4 of

http://www.aeroelectric.com/articles/grnding.pdf

It'a a 99% sure deal that if you start with the circuit
breaker at the bus and replace and/or clean-refurbish
ALL metallic joints between the bus and the voltage
regulator, the problem will go away for the twenty+
years it took for the root cause of the problem to
build up.

I've never encountered a mechanic that had heard of
this nor an instructor that included it in his/her
teachings. The slow build of TOTAL resistance in
the power path that supplies field current AND
shares bus voltage sense duties will eventually cause
ALL airplanes to do this. The Cessnas are the worst
because of the gross numbers of metallic joints in
this power path.

Replacing ONE of the many components may cause it
go reduce or go away leading the observer to believe
he/she has "slain the dragon". In fact, until all
the dragons are cleaned out, others will grow to
sufficient size to become the triggering event.

Metallic joint include those inside the breaker,
master switch, any OV relays, connector pins,
and crimps to wires. Each is small but they all
add up.

An alternative is to replace the stock 'ford' style
regulator with a more modern device that has a
separate bus voltage sense wire apart from that
which carries field current.

Bob . . .

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egilroy(at)gmail.com
Guest
PostPosted: Mon Sep 01, 2008 3:03 am    Post subject: Dancing Ammeter Reply with quote
Bob:

I see that I have stepped in a streaming pile on a path that others have blazed before me !!!

As for the excellent references, they describe the situation exactly, I will investigate as you suggest.

Many thanks...

Ed



On Sun, Aug 31, 2008 at 9:22 PM, Robert L. Nuckolls, III <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:
[quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>

At 06:20 PM 8/31/2008 -0400, you wrote:
Quote:
Hello:

Been a member for a few weeks now, trying to figure out a problem on a club 172 (building a RV-Cool.

The term "dancing" seems to be applied to what is happening. With light load on (no landing/taxi lights, pitot heat, etc) the ammeter makes a rhythmic swing around the zero point of the meter. I would guess 60-80 times per second. This started a year ago and our A+P says no big deal, at least 3 ships at our airport have the same problem!!! With a heavy, full load (turn everything on), ammeter firms right up.

I had a nasty alternator/battery failure last november inside the NYC VFR corridor (no place to lose your comm!!!) and replaced alternator + regulator but this problem stills haunts us. We recently swapped the regulator with another, no joy.

Ideas on how to proceed?



See list-server thread at:

http://tinyurl.com/6fb32p

also top of column 2 on the last page of:

http://www.aeroelectric.com/Mfgr_Data/Regulators/Zeftronics/R15V00_Ford_Style_Reulator.pdf

and column 2, third paragraph, page 4 of

http://www.aeroelectric.com/articles/grnding.pdf

It'a a 99% sure deal that if you start with the circuit
breaker at the bus and replace and/or clean-refurbish
ALL metallic joints between the bus and the voltage
regulator, the problem will go away for the twenty+
years it took for the root cause of the problem to
build up.

I've never encountered a mechanic that had heard of
this nor an instructor that included it in his/her
teachings. The slow build of TOTAL resistance in
the power path that supplies field current AND
shares bus voltage sense duties will eventually cause
ALL airplanes to do this. The Cessnas are the worst
because of the gross numbers of metallic joints in
this power path.

Replacing ONE of the many components may cause it
go reduce or go away leading the observer to believe
he/she has "slain the dragon". In fact, until all
the dragons are cleaned out, others will grow to
sufficient size to become the triggering event.

Metallic joint include those inside the breaker,
master switch, any OV relays, connector pins,
and crimps to wires. Each is small but they all
add up.

An alternative is to replace the stock 'ford' style
regulator with a more modern device that has a
separate bus voltage sense wire apart from that
which carries field current.

Bob . . .








[b]

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nuckolls.bob(at)cox.net
Guest
PostPosted: Mon Sep 01, 2008 9:59 am    Post subject: Dancing Ammeter Reply with quote
At 07:01 AM 9/1/2008 -0400, you wrote:
Quote:
Bob:

I see that I have stepped in a streaming pile on a path that others
have blazed before me !!!

As for the excellent references, they describe the situation exactly,
I will investigate as you suggest.

Many thanks...

Ed

My pleasure sir! Let me know how it works out.

Bob . . .

- The Matronics AeroElectric-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:

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