What have I done!

[artmin]

Thanks Robin, never heard of protection diodes but there is a diode beside each relay on the power board:



I had taken leads from the coil pins of the existing relay on the underside of the power board to supply my additional relay. Maybe this extra load could overload the circuit, but the relays are still working okay using the manual override switches on the front panel. I didn't notice or smell any smoke at any point. Saying that I was flapping around at this point. Can't see any burn't components anywhere.