Microgenus 27 mffi no power

[dean.]

Hi, Im working on a Ariston Microgenus 27 mffi, there was 240v going into boiler but nothing happening with no lights coming on. The pcb was burned so I replaced the board but it hasn't fixed the fault. there is no fault lights on but there is 240 coming in. any suggestions before I ring tech in the morning. thanks.

 

[woodsy]

Internal fuse ?

 

[dean.]

the fuses on the pcb or ok , cheers

 

[mountainman]

About a third of the way down the connector there are two orange wires with one wire separating them.
This is the power out from the pcb.
If you have power into the pcb and nothing on this wire then the new pcb is dead.
I had a new pcb last only 3 days recently.

Also check that the fan is ok because this will kill the pcb.

 

[dean.]

ill check that in the morning, thanks

 

[Billy Bob Bob]

you need to check the green power in plug and swap the wires around they sometimes come with the pins in different places,early microgenus boilers are a 3 way plug but the lives in a different place,the plug is re-wirable on the new pcb if you dont notice this little bugger you will get your exact fault 240v in but nothing else happening

 

[dean.]

yea ill give it a check, I know the plug u mean it was a 3 pin on the old pcb but the new one is 2 pin so I moved the live in one, ill give it a check again.

 

[dean.]

It ended up being the dhw flow sensor was faulty and causing the fault in the board.

 

[Billy Bob Bob]

It ended up being the dhw flow sensor was faulty and causing the fault in the board.

but that would not affect ch mode

 

[dean.]

because it was faulty it had wrecked the old board, When I fitted the new board it was stopping all the power going to the boiler so had no lights on, it was tech who said to remove flow sensor connector, doing this brought the boiler on again for ch, I replaced the sensor today and its now working on both. tech said a faulty flow sensor can spike the pcb.