Fixed my boiler in a day with change from £3.50 for parts, yes, really, three pounds fifty! Potterton Suprima 50, nine years old, now working fine again with its original PCB.
It starting locking out with the flashing red LED on rare occasions, then increasing in frequency to every couple of weeks then daily. Then it reached the point where pressing the reset button caused strange things happening like both lights flashing, relays clattering and then powering off completely until resetting at the power switch.
The fix? There are two parts to it.
Before the first part, SWITCH THE MAINS OFF - DON'T GET BUZZED!
If you don't feel confident isolating the system before commencing work on it, call in a professional.
First, all the comments you may have read about dry joints and poor solder flow for the PCBs in Potterton boilers are absolutely correct. This is the second home I've had with a Potterton boiler having dry joints and tired soldering on the main PCB, and friends have had similar troubles with theirs too. If you're an electronics person, or you know one, it's absolutely worth soldering everything in sight. Dry joints particularly appear on components which are large like the ignition coil, on components which have moving parts like the relays, components which run hot like large resistors and voltage suppressors and anything with fat pins, which flow soldering can't adequately heat up during manufacture, like the sockets for the wiring harness plugs. For clues where the hot components are, inspect both sides of the board for browned areas.
The second part of the fix, rectifying what temporarily killed my boiler, involves replacing the electrolytic capacitors on the PCB. The biggest one on the board, C22, is the reservoir capacitor for storing charge for pulsing current through the ignition coil. On my board this had 'burst its base' and torn a leg off. Electrolytic capacitors have a limited lifespan, especially when they work in warm environments, so I replaced all seven of them on the board as a precaution. For reference, they are:
C12, 1uF (one microfarad), 100V (one hundred volts).
C22, 47uF, 100V.
C24, 1uF, 50V.
C25, 1uF, 50V.
C29, 47uF, 63V.
C37, 4.7uF, 63V.
C51, Axial, 10uF, 25V.
Its worth noting that these (electrolytic) capacitors don't have to show any visible signs if they failed, so change them anyway. If you want your replacement components to have a long life buy capacitors designed for working in hot environments or with a high thermal specification. LOW ESR capacitors are also better than 'Hi Q' ones.
C51 being axial is mounted flat on the board alongside an IC (chip). All the others are radial, mounted upright.
If you can't obtain capacitors that have identical values for both capacity in microfarads and voltage then choose a capacitor with a higher voltage rating but keep the capacity in microfarads the same.
Hope this helps a few people!
Regards,
Chris
It starting locking out with the flashing red LED on rare occasions, then increasing in frequency to every couple of weeks then daily. Then it reached the point where pressing the reset button caused strange things happening like both lights flashing, relays clattering and then powering off completely until resetting at the power switch.
The fix? There are two parts to it.
Before the first part, SWITCH THE MAINS OFF - DON'T GET BUZZED!
If you don't feel confident isolating the system before commencing work on it, call in a professional.
First, all the comments you may have read about dry joints and poor solder flow for the PCBs in Potterton boilers are absolutely correct. This is the second home I've had with a Potterton boiler having dry joints and tired soldering on the main PCB, and friends have had similar troubles with theirs too. If you're an electronics person, or you know one, it's absolutely worth soldering everything in sight. Dry joints particularly appear on components which are large like the ignition coil, on components which have moving parts like the relays, components which run hot like large resistors and voltage suppressors and anything with fat pins, which flow soldering can't adequately heat up during manufacture, like the sockets for the wiring harness plugs. For clues where the hot components are, inspect both sides of the board for browned areas.
The second part of the fix, rectifying what temporarily killed my boiler, involves replacing the electrolytic capacitors on the PCB. The biggest one on the board, C22, is the reservoir capacitor for storing charge for pulsing current through the ignition coil. On my board this had 'burst its base' and torn a leg off. Electrolytic capacitors have a limited lifespan, especially when they work in warm environments, so I replaced all seven of them on the board as a precaution. For reference, they are:
C12, 1uF (one microfarad), 100V (one hundred volts).
C22, 47uF, 100V.
C24, 1uF, 50V.
C25, 1uF, 50V.
C29, 47uF, 63V.
C37, 4.7uF, 63V.
C51, Axial, 10uF, 25V.
Its worth noting that these (electrolytic) capacitors don't have to show any visible signs if they failed, so change them anyway. If you want your replacement components to have a long life buy capacitors designed for working in hot environments or with a high thermal specification. LOW ESR capacitors are also better than 'Hi Q' ones.
C51 being axial is mounted flat on the board alongside an IC (chip). All the others are radial, mounted upright.
If you can't obtain capacitors that have identical values for both capacity in microfarads and voltage then choose a capacitor with a higher voltage rating but keep the capacity in microfarads the same.
Hope this helps a few people!
Regards,
Chris
