On Saturday night my boiler suddenly stopped working, a quick investigation showed that one of the copper tracks on the pcb had burnt out. No problem I thought get a new pcb and job done. Replaced with new board (part no. 5112380) with the result that the DHW works fine but the CH goes through the ignition sequence, fires up for about a second and then shuts down. It will go through this sequence three times before showing a flame failure (30 light flashing). Resetting the boiler will clear the light but the same thing will happen each time. I've tried keeping it in the reset position for up to 15 seconds but still no joy. Have had the flame sensor replaced because the IM points to this as a possible cause, but still the same. In frustration I have soldered a piece of wire on the old board bridging the burnt out track put that back and the boiler is working fine in all respects, but each time I try the new board the CH will not fire up. Although its all working with old board in place I would like to put the new one in because I'm thinking there is possibly something wrong with the old one for it to burn a track out like that, so any help would really be appreciated here. Thanks in advance.
Baxi 105e pcb problem
- Thread starter fgp
- Start date
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I cannot guess whats wrong with your boiler but if I was investigating it there would be gas measurements which could well hold a clue to the problem.
You are very bold ( or foolhardy? ) to fit a new PCB after the previous one has been blown! Doing that usually just blows the new one!
The clue will be to trace the burnt out track to see which boiler component it leads to and that will almost certainly be associated with the fault.
Tony
You are very bold ( or foolhardy? ) to fit a new PCB after the previous one has been blown! Doing that usually just blows the new one!
The clue will be to trace the burnt out track to see which boiler component it leads to and that will almost certainly be associated with the fault.
Tony
N
namsag
Old board works New board doesnt now would it be that simple the new board has a fault on it.
Thanks for the response Tony, I think you're probably spot on with the gas measurements. After spending a few hours on the web trying to find an answer the general consensus seems to be something to do with the low pressure setting on the gas valve. So I guess I'll have to get the CORGI man to take a look at that.
Bold or foolhardy, ooh I'd go for the latter, definitely. ('
')
I don't want to take the old board out to take a look because it's all working fine at the moment but from memory the burnt out track was between a relay and either the pin that connects the board to the air pressure switch or the fan. Both of which work fine with the old board and even with the new board on the DHW side.
Again thanks for your time and trouble and any further thoughts you might have.
Frank
Bold or foolhardy, ooh I'd go for the latter, definitely. ('
')I don't want to take the old board out to take a look because it's all working fine at the moment but from memory the burnt out track was between a relay and either the pin that connects the board to the air pressure switch or the fan. Both of which work fine with the old board and even with the new board on the DHW side.
Again thanks for your time and trouble and any further thoughts you might have.
Frank
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Thanks for that namsag, I forgot to mention that this is the second board I've tried. I took the first one back because I thought it might be faulty and they gave me another one. Both boards doing exactly the same thing.
Frank
Frank
I would suggest that you check the value of the fuses.
The mains spur would normally have a 3A fuse and the PCB might have a fuse but I dont think so.
To reduce the chance of damaging anything further I would suggest that if the spur is 3A that you try using a 1A. You might get some nuisence blows but it might protect the PCB as the fault is probably still there.
If you could give me a part number for the new PCB and describe which track is blown I could see what might have blown it.
Tony
The mains spur would normally have a 3A fuse and the PCB might have a fuse but I dont think so.
To reduce the chance of damaging anything further I would suggest that if the spur is 3A that you try using a 1A. You might get some nuisence blows but it might protect the PCB as the fault is probably still there.
If you could give me a part number for the new PCB and describe which track is blown I could see what might have blown it.
Tony
I'll change the fuse as you suggest when I get a chance to get some 1A fuses, the boiler already has a 2A fast blow fuse fitted and the manual says the power consumption should be 190W so its worth a go.
The part number for the new board is 5112380, although the original old board (the one with the burnt track that I bridged and is in the boiler working now) is 248078, (maybe they changed the design for this reason?) anyway the track that burnt went from a relay to pin 6 on plug A2 which goes on a brown wire to the air pressure switch. Incidentally it looks like the burning started at the relay end of the track. I'm thinking maybe a dodgy soldered joint started arcing or something?
As before your help is greatly appreciated Tony, thanks
Frank
The part number for the new board is 5112380, although the original old board (the one with the burnt track that I bridged and is in the boiler working now) is 248078, (maybe they changed the design for this reason?) anyway the track that burnt went from a relay to pin 6 on plug A2 which goes on a brown wire to the air pressure switch. Incidentally it looks like the burning started at the relay end of the track. I'm thinking maybe a dodgy soldered joint started arcing or something?
As before your help is greatly appreciated Tony, thanks
Frank
Yes, of course it has a fuse in a carrier built into the choc block beside the PCB.
That being the case get some quick blow 1A fuses to put into that instead as they will probably blow quicker than the mains but change that to 1A as well.
I will look at the old PCB when I have a moment.
Tony
That being the case get some quick blow 1A fuses to put into that instead as they will probably blow quicker than the mains but change that to 1A as well.
I will look at the old PCB when I have a moment.
Tony
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