In message .uk, Ed
Sirett writes
On Mon, 03 Apr 2006 23:03:11 +0100, Vortex wrote:

Hi There,

3 or 4 weeks ago my trusty 12 year old Prima 80F boiler stopped working. At
the time I gave it a (small well calibrated) thump. It started working
again and I thought no more of it.

Today it failed again. In the specific failure mode:

...The controls are calling for heat.
...The pump is running and the fan is on.
...The pilot light is lit
...but no main burner.

I took off the bottom cover and can see the gas valve is connected to the
electrical control PCB/gubbins by a 4 way MOLEX style connector.

* If I carefully wiggle this connector the main burner lights straight
away.
* If I turn down the temperature control it turns off the main burner as
you would expect.
* When I turn up the temperature the boiler *sometimes* returns to the
failure mode.

I sense a dodgy connection or a dry joint.

Q. Is this a common failure mode?
Is there a specific connector or component that is the most common
source of this problem.
The benefit of your experience is appreciated!

You've found the fault.
You might be able to make a repair with your soldering iron. I've seen
this fault on similar models.

I had a similar fault on a Potterton profile.

The pc board connector pins had dry/cracked solder joints. As someone
suggested, at the time, you need a magnifying glass to spot which pins
need re-soldering. Go easy on the heat applied as softening the plastic
part of the connector is very likely:-(

There was quite a long thread here last Christmas, but I think you
already have the conclusions.

regards



--
Tim Lamb