"m kinsler" wrote in message
ps.com...
On Jun 20, 1:48 pm, "David Farber" wrote:
This 28 year old Stanley Vemco automatic gate uses mechanical relays.
The
problem is that the relays are noisy when either the opening or closing
sensor switches are activated at the end of its travel. For example,
somebody runs over the air hose to begin the open operation. You can
hear a
relay click with no problem, then the gate opens. Just before the gate
is
fully open, it enables a sensor switch which interrupts power to the
motor
relay. Then, you can hear one of the relays make a chattering noise
which
decays in about two seconds. The same thing happens when the gate
closes. It
seems to have gotten louder over the years. Since the entire circuit is
AC,

You've got a bad pair of contacts feeding the coil of one of the
relays. The chattering relay is probably not the one that is at
fault; the difficulty might well lie in that sensor switch. I've had
difficulties with magnetic reed switches in the past, and if there's
one there I would see about it. There may also be a bad connector
associated with the sensor switch. Find the wires that go to the
sensor switch and use a jumper across them to simulate the operation
of that switch. If the relays operate but do not chatter, then the
difficulty lies in the sensor switch or its wiring.

M Kinsler


Now that I've added the motor circuits to the schematic, you will notice
that the coil in the B relay is in series with what looks suspiciously like
a motor start capacitor. Can this be correct?

http://www.pbase.com/image/81471200

Thanks for your reply.
--
David Farber
David Farber's Service Center
L.A., CA