T&T: Electric horn problem

[Peter Bennett]

Wednesday, May 27, 2009, 12:39:42 AM, Stephen wrote:


SO> In the case of the horn that only growls - intermittent with no sound
SO> otherwise; I took a voltage reading at each horn button (upper and lower
SO> helms).  As predicted by Rudi, Larry, and the List; I read 12..5-12.7 until
SO> I pressed the button; then it dropped to zero at each button.

Where were you reading this 12.5 volts - between a switch terminal and
what else?

If you were measuring across the switch's two terminals, then your
result is to be expected.

You should measure between the horn's terminals - there you should
find zero volts until you press the button, when you should have 12.5V or so.


SO> Oh, by the way, on the lower helm horn button; there are two wires going to
SO> one button terminal.  I can't figure out why two wires?  The upper horn
SO> button has what I would expect; one wire to each terminal?  Could the second
SO> wire on the lower helm button be going to the upper horn button, so that the
SO> two are connected in series some how?  Or, maybe the second wire is a ground
SO> wire?  

Are the two wires on the "hot" (supply, 12V) terminal of the switch,
or on the switched terminal.  I would expect to see two wires on the
switched side of one of the switches - one of the wires would go to
the switched side of the other switch, the other to the horn.

If the two wires are on the hot terminal of the switch, one would be
from the breaker, and the other would go to the hot terminal of the
other switch.  Either way, the two switches are connected in parallel.

-- 
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
Ennos 31 "Honeycomb"
GPS and NMEA info: http://vancouver-webpages.com/peter 
Vancouver Power Squadron: http://vancouver.powersquadron.ca