Circuit boards

[clarkerothwell]

Is it possible to fault find on and repair circuit boards on boilers?
I just changed one and could see a suspect resister looked burnt out, board was 130 pound, thought could repair instead of replace.?

 

[DP]

Resistors do sometime look as if they are burnt out (higher wattage ones). If the resistor is burnt out, how are you going to check the value and tolerance?

 

[clarkerothwell]

thought they were colour coded? i would just replace like for like?

 

[Burnerman]

There's no reason that you shouldn't replace the resistor, if you are sure that you know what its value is...but not all are colour coded. You also need to ascertain that the wattage is correct, often determined by its physical size. However, resistors are a passive component, and the failure may be caused by something else.....but you've nothing to lose by giving it a go. Make sure that any fuse that you may need to replace is substituted by one of the exact value though - they are often unusual ratings, and replacement with one with even a slightly higher current rating can cause lots of damage.

 

[powermaxer]

well in this free world anyone can do anything as long as what they do is safe, hopefuly.
now a can of worms opens up.
the repair needs to meet standards so the repair needs to be checked by the original pcb maker.
in my opinion i would not reccomend a pcb repair,a secondhand pcb or a recon part.
well just my comments.
good luck.

 

[DP]

If the resistor is burnt, the colours will be there no more. Therefore, you will not know resistance or tolerance. Wattage- yes, value- no.

I have changed components on PCBs. If a relay is burnt out, and replacement is exactly the same, how is that going to alter the operation of the PCB? Why should the PCB then need rechecking by the manufacturer?

If I were to install a component that is different spec and different value, then obviously PCB operation may may have altered, hence needing rechecking on jigs no one other than makers will have.

 

[corgiman]

If the resistor is burnt, the colours will be there no more.

Blimey DP touch of Yoda Speech you have

 

[DP]

Exterminate...... exterminate..... exterminate!!!

 

[corgiman]

Exterminate...... exterminate..... exterminate!!!

thats a dalek you plum

 

[DP]

I know, I could not think of an appropriate remark. At age 61, brain is well gone watching sex and violence on the telly. Bromide in tea is not helping either.

 

[Agile]

If a resistor has burnt out it is not because the resistor has itself failed.

It has overheated as a result of something else that has failed!

Unless you had the skill to identify what has caused the resistor to fail then you would be wasting your time.

Tony

 

[mattylad]

Tony is spot on.

The resistor will only be burnt because there has been excess current drawn through it. The reason for that is usually something like a faulty transistor on the PCB or another component elsewhere in the boiler that has gone faulty.

What boiler is this PCB from?

I have seen this scenario lots of times on here, usually for the same boiler.

BTW, yes it is possible to repair the PCB's. I have done this several times myself to my boilers boards - but then I spent the last 14 years designing them. If your not into electronics & PCB fault diagnosis & repair then the consequences of not repairing it correctly could be bad as safety systems may not operate correctly.

 

[Agile]

Did you design any boiler PCBs?

Tony

 

[doitall]

Did you design any boiler PCBs?

Tony

If he did Tony he should quit while he's ahead.

 

[mattylad]

No, I designed PCB's that were far more complicated than the simple ones found in boilers