Repair of Scheiber Electronic Switching/Circuit Breakers?

[nigelmercier]

One way it might work is that once the coil of the relay is energised by pressing a normally open switch and the switched 12v output comes on, this is fed back into the coil of the relay. Then the relay remains on until another (normally closed) push switch in the feedback to the coil interrupts the current to the coil...

I did consider this, hadn't thought about a NC push button switch. Thanks.

So on to fault finding: what happens when ON switch is pressed?

Nothing: relay or ON switch faulty, there may be a series diode in the energise circuit.
Turns on momentarily: OFF switch faulty, there may be a series diode in the latch circuit.

 

[pvb]

One way it might work is that once the coil of the relay is energised by pressing a normally open switch and the switched 12v output comes on, this is fed back into the coil of the relay. Then the relay remains on until another (normally closed) push switch in the feedback to the coil interrupts the current to the coil. Hard to explain without a picture, but I mean the relay latches itself.

That was my guess too, and it does seem complex. However, I still can't see how the circuit breaker function can work.

 

[FullCircle]

I did consider this, hadn't thought about a NC push button switch. Thanks.

So on to fault finding: what happens when ON switch is pressed?

Nothing: relay or ON switch faulty, there may be a series diode in the energise circuit.
Turns on momentarily: OFF switch faulty, there may be a series diode in the latch circuit.

No LED light, even momentarily when pressed.

 

[nigelmercier]

No LED light, even momentarily when pressed.

OK, check if there is a voltage going from the ON switch to the relay coil.

Just checking that you are monitoring the output, not just relying on the LED, which could have blown.

 

[FullCircle]

OK, check if there is a voltage going from the ON switch to the relay coil.

Just checking that you are monitoring the output, not just relying on the LED, which could have blown.

Output is power to the water pump. No water pump, therefore no 12v.
well 13.2v actually but who is cpunting!

 

[rogerthebodger]

This is a typical latching relay circuit that may help

https://www.google.co.za/search?q=l...2Fwww.eleinmec.com%2Farticle.asp%3F24;270;280

 

[nigelmercier]

This is a typical latching relay circuit that may help ...

Rather too many!

This one will be close, but with a single pole relay, ignore terminals C & D, output is from A:

The OFF (Break) push-button switch can also be in the 0V connection.

So, need to test if +12V is leaving the top switch.