I have had a read-around here and cannot find quite the same symptom,
but then Potterton are popular here so it may have been lost in the
noise.

From cold, the timer kicks in for HW, and all is well, when it is up to
temperature it seems that it lights periodically to maintain the
temperature as expected, however one of these relights seem to fail.

In the fault condition, the boiler is out, fan is no longer turning,
the red led is flashing and the pump is running. This condition will
last indefinitley. Pressing reset while the HW is off just stops the
pump, if HW is on the fan turns, pump runs and after a few secs, gas,
spark and normaillity again. (Changing the pump speed also stops the
pump).

The frequency of occurence has built up over the last 2 years.

I thought it was the pump, since the pump body was hotter than all the
pipework around it, and speed 2 seemed to do nothing, so I swapped in a
Wilo Gold 60 for the old Myson CP53.

However the fault persists.

Unit is 5 yr old, fitted by builder, serviced once professionally (he
condemmed installation, builder fixed it same day) since then I have
checked the combustion chamber for soot etc, completely clean so I
figured best left well alone.

So before I disassemble it completely to diagnose I thought I would see
if this is a common problem.

Chris

In message .com,
writes
I have had a read-around here and cannot find quite the same symptom,
but then Potterton are popular here so it may have been lost in the
noise.

From cold, the timer kicks in for HW, and all is well, when it is up to
temperature it seems that it lights periodically to maintain the
temperature as expected, however one of these relights seem to fail.

In the fault condition, the boiler is out, fan is no longer turning,
the red led is flashing and the pump is running. This condition will
last indefinitley. Pressing reset while the HW is off just stops the
pump, if HW is on the fan turns, pump runs and after a few secs, gas,
spark and normaillity again. (Changing the pump speed also stops the
pump).

The frequency of occurence has built up over the last 2 years.

I thought it was the pump, since the pump body was hotter than all the
pipework around it, and speed 2 seemed to do nothing, so I swapped in a
Wilo Gold 60 for the old Myson CP53.

However the fault persists.

Unit is 5 yr old, fitted by builder, serviced once professionally (he
condemmed installation, builder fixed it same day) since then I have
checked the combustion chamber for soot etc, completely clean so I
figured best left well alone.

So before I disassemble it completely to diagnose I thought I would see
if this is a common problem.

Fairly typical pcb fault - the pump run on is a safety feature

I'm not sure quite you are going to be able to diagnose by pulling it
apart

--
geoff

raden wrote:
In message .com,
writes
I have had a read-around here and cannot find quite the same symptom,
but then Potterton are popular here so it may have been lost in the
noise.

From cold, the timer kicks in for HW, and all is well, when it is up to
temperature it seems that it lights periodically to maintain the
temperature as expected, however one of these relights seem to fail.

In the fault condition, the boiler is out, fan is no longer turning,
the red led is flashing and the pump is running. This condition will
last indefinitley. Pressing reset while the HW is off just stops the
pump, if HW is on the fan turns, pump runs and after a few secs, gas,
spark and normaillity again. (Changing the pump speed also stops the
pump).

The frequency of occurence has built up over the last 2 years.

I thought it was the pump, since the pump body was hotter than all the
pipework around it, and speed 2 seemed to do nothing, so I swapped in a
Wilo Gold 60 for the old Myson CP53.

However the fault persists.

Unit is 5 yr old, fitted by builder, serviced once professionally (he
condemmed installation, builder fixed it same day) since then I have
checked the combustion chamber for soot etc, completely clean so I
figured best left well alone.

So before I disassemble it completely to diagnose I thought I would see
if this is a common problem.

Fairly typical pcb fault - the pump run on is a safety feature

I'm not sure quite you are going to be able to diagnose by pulling it apart

have you got the MI, is there a fault finding guide in there? usually
the led will flash in a certain way or the symptoms will be described.
it seems that after reaching temp, some thing is telling the boiler to
keep firing??

i have a copy of the instructions and it does have a fault find on page
34. go through the sequence of events and 'find' the problem, i can
email it to you if you need

In message , Gav
writes
raden wrote:
In message .com,
writes
I have had a read-around here and cannot find quite the same symptom,
but then Potterton are popular here so it may have been lost in the
noise.

However the fault persists.

Unit is 5 yr old, fitted by builder, serviced once professionally (he
condemmed installation, builder fixed it same day) since then I have
checked the combustion chamber for soot etc, completely clean so I
figured best left well alone.

So before I disassemble it completely to diagnose I thought I would see
if this is a common problem.

Fairly typical pcb fault - the pump run on is a safety feature
I'm not sure quite you are going to be able to diagnose by pulling
it apart

have you got the MI, is there a fault finding guide in there? usually
the led will flash in a certain way

I think that on and off is how it normally flashes

.... or is that off and on ?



--
geoff

Gav,

I may take you up on the offer, I will have a look in the garage
tomorrow for the manual.

Geoff,

I was looking for someone who has seen this before, I find that usually
this is the quickest way to diagnose a fault.

I used to fix TVs, with a C&G and BEng in Electronic Engineering I sure
hope I can diagnose it

Chris

In message .com,
writes
Gav,

I may take you up on the offer, I will have a look in the garage
tomorrow for the manual.

Geoff,

I was looking for someone who has seen this before, I find that usually
this is the quickest way to diagnose a fault.

I used to fix TVs, with a C&G and BEng in Electronic Engineering I sure
hope I can diagnose it

As someone who repairs these pcbs, I'm totally sure you wont, you'll
bugger up the pcb then send it in to me to fix.


--
geoff

Hi Geoff,

If it is a choice between several evenings messing around and £50 for
a reconditioned PCB, then it seems fair enough, if only I knew for sure
it was the board!

I will feel foolish if I don't at least check for dry joints and test
the easier sensors.

Chris

As someone who repairs these pcbs, I'm totally sure you wont, you'll
bugger up the pcb then send it in to me to fix.


--
geoff

On Tue, 29 Aug 2006 06:11:06 -0700, chrisaaaaa wrote:

Hi Geoff,

If it is a choice between several evenings messing around and £50 for
a reconditioned PCB, then it seems fair enough, if only I knew for sure
it was the board!

I will feel foolish if I don't at least check for dry joints and test
the easier sensors.


notorious that you are on a pretty safe bet to go for the PCB first.
Usually you are right but the boards in the Potty Suprimas are _so_
Please don't top post.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

In message . com,
writes
Hi Geoff,

If it is a choice between several evenings messing around and £50 for
a reconditioned PCB, then it seems fair enough, if only I knew for sure
it was the board!

I will feel foolish if I don't at least check for dry joints and test
the easier sensors.

Well the temp sensor is a meg at 20C
Air pressure switch is either short circuit or open
gas valve 4ksomething IIRC

If you have a red HT lead, replace it
it's distributed carbon and prone to fail on flame sensing

the manual is wrong on the volts to the gas valve - it should be about
240vDC, if it's 300v, then the gas valve (or loom) are knacked


Chris

As someone who repairs these pcbs, I'm totally sure you wont, you'll
bugger up the pcb then send it in to me to fix.


--
geoff


--
geoff

On Tue, 29 Aug 2006 19:38:40 +0000, raden wrote:



the manual is wrong on the volts to the gas valve - it should be about
240vDC, if it's 300v, then the gas valve (or loom) are knacked

Perhaps the writer of the manual was taking measurements from a typical
unit on a rig in the factory?!?


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

Thanks for all the help guys.

In this case it was the PCB, I took it out Tuesday to check for dry
joints.

The board was a bit of a mess, so I cleaned it up with Isopropal, there
were no very obvious drys, but loads of suspicious looking joints. At
least a dozen sizzled nicely when I reheated them.

Around the ICs the excess solder and crud looked like it may bridge
pins so I removed some of the solder and cleaned between the pins.

After all that it fired up 1st time and has worked correctly for 3 days
- touch wood.

And the Wilo pump is way quiter than the Myson it replaced.

Chris



Ed Sirett wrote:
On Tue, 29 Aug 2006 19:38:40 +0000, raden wrote:



the manual is wrong on the volts to the gas valve - it should be about
240vDC, if it's 300v, then the gas valve (or loom) are knacked

Perhaps the writer of the manual was taking measurements from a typical
unit on a rig in the factory?!?


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards