Baxi Solo 2 50PF - Won't start... help please..!!!

[Pete.Cupra.R]

Hi people...new to the forum.
Can anyone help me please..
My Baxi Solo 2 50PF will not start. The boiler on light is on and the system is calling for heat but the fan doesn't start or even try to, nothing happens at all. Obviously if the fan doesn't start then the pilot doesn't light etc etc
There is live and switch live.
The control valves open, pump runs but the boiler does nothing.
I have checked the potentiometer switch, thermostat sensor, pilot and main gas solenoids, overheat thermostat and all are ok. I'm presuming it's the PCB but I don't want to change it for nothing.... I expect they're expensive.
The only thing I haven't checked is the pressure switch cause I'm not sure exactly what I should do.

Point to make: For some reason my pump isn't wired from the boiler and is always on..... strange I think...... but it has worked for many a year so I don't think this is anything to do with the problem.

 

[PEDANTICVINDICTIVEMAN]

Most likely nacked fan, check for 240 volts at fan terminals, if so def fan.

 

[Pete.Cupra.R]

cheers but there is no voltage at terminals cause it's not even trying to start the fan
fan is ok...... I've run it up

 

[Pete.Cupra.R]

Can anyone help
Pleeeeease...!!!!

 

[PEDANTICVINDICTIVEMAN]

Does sound pcb, one for agile methinks

 

[corgigazza]

The pcb has an internal fuse that may have blown due to faulty fan, if fuse goes it still lights some of the neons on the board. thermistor may be out of calibration use your instructions to fault find.

 

[gazthepottertonengineer]

one other thing to check is the gas valve pilot solenoid cos if this is knackered it gives this exact fault ive had it before the fault that is

 

[ChrisR]

The APS is a changeover type, so the boler probably checks it thinks the fan is OFF before powering up the fan - so check the aps switch changes state on both terminals. Don't blow hard into the tubes or you'll break it - just blow AT the tube.

This is corgi only territory really so I'll probably delete this when I'm feeling more strict.