Graham Francis
Member
- Messages
- 46
- Location
- Tenbury Wells
OK. Some more information from some more testing just now. I disconnected the two blue wires from T1 (one going to the fan and the other to terminal A4 on the PCB connector. This effectively just left the fan connected to A4 and nothing else. I reconnected up the PCB and replaced the fuse and turned the power on. The fan started up and the fuse didn't blow.
I then checked the voltage on the terminal on T1 that the two blue wires connect to and I was seeing nothing on my meter with one side connected to earth and the other to the T1 terminal. I then put my meter across the T1 terminal with the two black wires and the terminal for the two blue wires and I'm seeing 240V. From this I conclude that the 'two blue wire' terminal on T1 is neutral as I see 240 V across the black wires and earth.
Next thing I did was to switch everything off and re-connect the two blue wires. I turned it back on and BANG FLASH went the fuse! I'm guessing because if the blue wire terminal is neutral into A4 and the other feed to the fuse (being the grey into A3) is 240V, then effectively I'm creating a direct short.
With it all switched off, I checked resistance between the blue wire terminal on T1 and earth and it appears to be open circuit, hence no short. I would have expected the blue wire terminal on T1 to be a live feed rather than neutral. Alternatively, perhaps there shouldn't be 240V on the grey wire that comes out of the connector box thing with the large resistor.
In either case, shoving live and neutral directly across the fuse is what's causing it to blow, but why this is now the case, I don't know. Could it be that T1 has failed? if so, I would have expected the transformer windings to have either gone open circuit or shorted to earth as opposed to a change of polarity.
Onwards and upwards :-)
Graham
I then checked the voltage on the terminal on T1 that the two blue wires connect to and I was seeing nothing on my meter with one side connected to earth and the other to the T1 terminal. I then put my meter across the T1 terminal with the two black wires and the terminal for the two blue wires and I'm seeing 240V. From this I conclude that the 'two blue wire' terminal on T1 is neutral as I see 240 V across the black wires and earth.
Next thing I did was to switch everything off and re-connect the two blue wires. I turned it back on and BANG FLASH went the fuse! I'm guessing because if the blue wire terminal is neutral into A4 and the other feed to the fuse (being the grey into A3) is 240V, then effectively I'm creating a direct short.
With it all switched off, I checked resistance between the blue wire terminal on T1 and earth and it appears to be open circuit, hence no short. I would have expected the blue wire terminal on T1 to be a live feed rather than neutral. Alternatively, perhaps there shouldn't be 240V on the grey wire that comes out of the connector box thing with the large resistor.
In either case, shoving live and neutral directly across the fuse is what's causing it to blow, but why this is now the case, I don't know. Could it be that T1 has failed? if so, I would have expected the transformer windings to have either gone open circuit or shorted to earth as opposed to a change of polarity.
Onwards and upwards :-)
Graham