Ideal Logic Code Combi ES38 not working

[jimmystavros]

Turned the system from hot water only, to hot water and central heating the other day. After it working briefly, it has now stopped all together. The display isnt showing a fault or anything - it is just blank.

After reading the service guide that came with it - I am confident there is power getting everywhere it needs to, and have even replaced the CUI board that shows the display and has the pots on it for the dials - but still nothing.

The only other thing I can see is there appears to be one chip on the main PCB that has some scorch marks around it - could this be the problem, or is there anything else I can try/check? Pics of the chip in question in the link below:

2 new items by James Middleton

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Ideal

 

[DP]

That is a bridge rectifier.
I suspect you had water spillage there
Hard to say if low voltage or mains (SWPS) going through thart rectifier
Have you checked the fuse?
What fuse rating on the spur fuse ( often see 13amp still in place)

 

[jimmystavros]

Fuse in the wall is working fine, that is a 3A one.
Not checked the fuse on the board, I will check that.
Will that bridge rectifier cause the system to not work at all? From my understanding, that side half of the board is the mains voltage side.

 

[jimmystavros]

I am pretty sure the 4A fuse on the PCB isnt working. If I just replace it - will it just blow again because of the damaged bridge rectifier, or might it work OK and the fuse just tripped with the initial potential water damage?

 

[RandomGrinch]

I may be wrong, but I believe the rectifier is associated with the gas valve.
If the PCB is damaged like that, it's likely that whatever is being controlled down the line (i.e. the gas valve) is at fault.
Just changing the rectifier, or even the PCB could have the same outcome, if the true fault isn't found.
Is the boiler under warranty?

 

[jimmystavros]

No, it is out of warranty. It looks like a bridge rectifier takes the AC mains input and converts it to a useable DC output, so it sounds like it is working from mains and then passing that on, making me think that it wouldn't be affect by something further down the line. I am no an expert though!

As a test, I found a 3.15A fuse. The unit turned on no problem, but as soon as I turned the hot water on, the fuse blew, making me think that component that looks burnt out is causing a short and is the problem. I think I am going to try and get a replacement PCB and see if that works.

 

[RandomGrinch]

I think I am going to try and get a replacement PCB and see if that works.

Then I'm afraid you are likely to lose another PCB.
I would strongly recommend that you get an RGI to check and replace the gas valve.

 

[jimmystavros]

Then I'm afraid you are likely to lose another PCB.
I would strongly recommend that you get an RGI to check and replace the gas valve.

OK, thanks, I appreciate your input and will look into this.

 

[RandomGrinch]

Just a quick additional note...

The bridge rectifier is a DF10S - rated for 1000V @ 1A

However, it also has a peak surge overload rating of 50A - far higher than the rating of the boilers internal fuse.
It's possible that the rectifier is still operational, and the PCB traces have taken the brunt of the overload current.