F33A Bonanza Alternator Light

Light comes on occasionally...extinguishes itself in 2 or 3 seconds.
Mechanic's inspection reveals nothing. Light has come on once or twice in
the past and required manual switch reset which worked. Any advice or
experience would be appreciated.

Peter Shurman
Bonanza F33-A C/GRDT
Toronto ON

Yea, have your mechanic check the coupling, and do it quickly before
it comes apart.

On Sat, 12 Jul 2003 15:18:49 GMT, "Peter Shurman"
wrote:

Light comes on occasionally...extinguishes itself in 2 or 3 seconds.
Mechanic's inspection reveals nothing. Light has come on once or twice in
the past and required manual switch reset which worked. Any advice or
experience would be appreciated.

Peter Shurman
Bonanza F33-A C/GRDT
Toronto ON

"Peter Shurman" wrote in message ble.rogers.com...
Light comes on occasionally...extinguishes itself in 2 or 3 seconds.
Mechanic's inspection reveals nothing. Light has come on once or twice in
the past and required manual switch reset which worked. Any advice or
experience would be appreciated.

Peter Shurman
Bonanza F33-A C/GRDT
Toronto ON


Don't know you serial #, but on the vast majority of 14 v F33s, the
problem is in the ALT light circuit itself.

They way they work the light is to look at the center of the Y winding on
the alternator. It's not connected to the regulator at all.

If all the diodes are conducting correctly and there is current
flowing out of the alternator, the center of the Y will sit at
half of the bus voltage, or about 7 volts plus some diode drops.

This works a relay thru a fuse. When the relay pulls in by the 7
volts, the C-side contacts on it turn the light off.

Culprits are ususally the fuseholder getting dirty or the
relay itself. (Located on the firewall under the football panel).

IS the alternator failure real? When the light comes on,
do you show a discharge on your amp meter? If so, it's a
real failure, not an indicator failure.

If you have to cycle the alternator or master switch to get
it back, it is an over-voltage trip.

Most likely causes: 1) Low battery water or bad connections on
the battery; 2) OV half of regulator is failing; 3) Regulator
side of the regulator is set too high (measure ~13.8v while
run up and some loads like nav lites on).

On many of
the 14 volt regulators that are mounted above the copilot rudder
pedals, there are two halves: one is the actual voltage regulator
and the other is the over-voltage protection. Due to design that
isn't too great, there are stacks of little PC boards and lugs
intermixed with pheonolic spacers on the long screws that hold the
TO-3 transistors on the top. The spacers shrink over time, yet
the design depends on contact being made by the lugs :-(.

FAA Approved, of course.

I've successfully fixed a few OV
situations by removing the regulator and carefully tightening
all 4 of the TO-3 mount screws. Not approved, of course. Check
the bus charging voltage afterward.

I can assure that you if it is the drive coupling that it won't
be intermittent!! But you have inspected it and the bearings
in the alternator in the last 400 hours or so, no?

Incidentally, one of the six diodes can be frapped and the
ALT light will not come on (!!) But you will show a discharge on
your amp meter unless the load is very light or you have a lot
of RPM. The radios and intercom will probably whine then too.

More than you wanted to know.

Bill Hale BPPP Systems Instructor.

Good advice, Bill knows his stuff
MikeM

Bill Hale wrote:

Don't know you serial #, but on the vast majority of 14 v F33s, the
problem is in the ALT light circuit itself.

. . .

i didn't get to read the original
question...but i have a baron and
one of the alternator lights is intermittent.

it seems to be picking up the load though.

connection problems? bad belt?

bman

"MikeM" wrote in message
...
Good advice, Bill knows his stuff
MikeM

Bill Hale wrote:

Don't know you serial #, but on the vast majority of 14 v F33s, the
problem is in the ALT light circuit itself.

. . .