(GMCnet) Macerator circuit troubleshooting

[tom whitton1]

I need some help with a macerator problem. It's a mounted macerator with an emergency bypass valve to empty to a conventional sewer hose when necessary. When switched on, the relay chatters and the motor won't run. I removed the pump and motor, connected the leads directly to the battery and the motor/pump runs fine. The battery and circuit breaker are up front with wires running to to the relay and switch. I have a schematic that I can email to anyone willing to suggest how to find the problem. I have messed with it a long time without success. The circuit was designed by a friend of mine who was good at electronics but, unfortunately, has passed away. It all worked for years until now. Need suggestions......

Here's the circuit:

battery + to circuit breaker
circuit breaker to relay
relay to switch
switch to ground

battery - to pump
pump to relay

Thanks,
Tom Whitton
26 ft. upgraded GMC
Paducah, Ky

 

[billvv]

There's two circuits. Once circuit runs from the circuit breaker to the switch and energizes the relay coil when the switch is thrown. The other
circuit runs (branches off) from the positive side of the coil, through the relay contacts, and to the pump. When the switch energizes the relay coil,
the relay contacts close and start the pump. A chattering relay generally means that the voltage is low at the relay coil - or goes low when the load
is added to the circuit - at that point there's not enough voltage to hold the armature of the relay so it closes. Once it closes the voltage goes
back up, picks up the relay and .... rinse and repeat. Could be a bad coil in the relay or a high resistance somewhere in either circuit - often a bad
connection.

--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.

 

[Ken B]

I totally agree with Bill. This sounds like a poor / corroded connection but it could be other things.

I do not know what electrical tools you have or are using. Test light or voltmeter?

To chatter the relay there has to be a poor connection, (probably on the positive side), a bad CB, or bad relay coil or contact. I would start by
probing on the output of the CB and see what voltage you have there when the relay is chattering.

Do not bother metering anything past the relay and on to the motor because we know that will be bouncing because the relay is chattering.

A side comment: Any component / connection that is warm or hot after chattering the relay a bit is a bad connection. I would be looking at
connections first. This also could be a weak or almost dead battery. You might throw a meter across the battery an observe the battery voltage while
it is chattering.

Lots of things can cause this. You just need to find the culprit.

Ken B.



--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana