In message , Harry Stottle
writes

"Mark" wrote in message
.. .
On Wed, 21 Jan 2009 23:10:24 -0000, Colin Wilson
o.uk wrote:

Funnily enough, the PCB on our Worcester Bosch has had to be replaced
either two or three times now, along with pretty much everything else
electrical in it (fan, transformer and so on)

The PCB on the WB is also a POS that is designed to break if the fan
goes - no damage limitation devices such as (gasp) a fuse.

The PCB on my WB boiler did not fail when the fan died.


It could be that the first guess for a repair is the PCB, then when this is
replaced and is found to have not cured the problem, the real culprit is
detected and replaced, i.e. the fan. The original PCB should have been
refitted after the new replacement had made no difference, and before
fitting a new 'fan', but it is easier, and more profitable, to say that the
fan has damaged the PCB, so the new PCB is left in situ and charged for,
along with the fan. I accept that a faulty component 'can' damage a
PCB, and that PCB's do fail on their own, but there seems to be a lot
of PCB's being replaced, a lot more than should be expected.


As I said, fans on WBs are relay driven, and, with the exception of a
dead short on the windings blowing a track (I've never seen it happen
and few have seen more than I have)

The point that you seem to not quite have grasped is that the PCB is the
most complicated and mystifying part of the boiler to a fitter, and once
they have replaced that, they are back on relatively safe ground

So they replace the PCB - just in case it's where the fault lies and
then they invent some bull**** like "Oh and the fan is faulty as well -
it blew the pcb" ... utter rubbish

--
geoff