Ideal Instinct PCB

30 Jan 2023
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United Kingdom
I am aware I am not a gas engineer btw..

So long story short, my boiler is bricked. No display, nothing. Background is that I started fitting a Drayton Wiser Hub and thermostat. While I got it wired in fine the boiler failed to light when the Wiser Hub called for heat. It was getting late and the house was cold so I disconnected the wiser and replaced all the previous wiring for the original SALUS RF500BC controller. Unfortunately not long after shutting the thing up it made an electrical pop noise which led to its current condition. The fuse on the supply spur is fine and the boiler has 240v. As I said before all the wiring is as it was previously, the only thing I can see different is a small bit of discolouration on the PCB next to one of the connectors. I guess my question is, is the pcb dead, and if so why!? In the past we have had this boiler play up and refuse to light. When this happened before an engineer came out and wiggled the pcb and it just started working, he didn't know why. Could it be this pcb is just dodgy? I've include a diagram of the PCB with the suspect link wire which I think may have gone pop.

Wiring before


Wiring after




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Once the smoke has been released from electronics, it can be very difficult to put the smoke back in. The component you have circled in green, could be many things - opto-isolator/bridge diode etc.. The only way to be sure what it is, via the part numbers printed upon it. Even then, even if replaced, there is no certainty that is the only damage. Which is where the specialists come in, and offer repaired and refurbished and fully tested PCB's. There is no certainty that fitting a PCB will fix it, there could possibly be damage to the boiler other components and sensors too.

A good safe option at this stage, might be to see if the boiler manufacturer offers a fixed price repair.
the board has a fast blow fuse on it have you checked that
I hadn't, just checked it now. There is no continuity so it has blown.
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Thanks @gas112 , unfortunately I don't have a spare to try it out. I have an engineer coming to look later. Hopefully he will have one on his van. The wiring looks fine so it is still a mystery to me, which I think is the most frustrating part.
I hadn't, just checked it now. There is no continuity so it has blown.

That is the sort of fuse, you might have difficulty in finding a replacement for. A TV repairer might stock them, or RadioSpares now called RS if there is one near you will certainly stock them. Check the details stamped onto the end cap of the fuse.
2.0amp? plumb centre usually have regin ones on the shelf
I don't think so, that's just where the PCB makes the connection between the component and the leads. It's the two terminals on the leads side that seem a bit blackened/discoloured
As the heat spot is away from the what looks like a mos rectifier, that could just be from a poor fitting edge connecter getting a bit hot.

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