why does this happen?????

[onlyfitidealboilers]

why does this happen..

i fit loads of new pcbs because other parts like the fan or a pump blows them

the pcb has fuse protection, so why does it blow the pcb..

 

[ban-all-sheds]

So you and the manufacturer can make more money.

 

[electronicsuk]

Generally speaking, fuses don't react quickly enough to prevent damage to the semiconductors that they are supposed to protect. As manufacturers insist on adding more and more technology to boilers, it's no longer possible to control everything using electromechanical components such as relays. Even basic components such as the pump and flue fan must now be semiconductor controlled to provide variable speed.

The boiler manufacturers could make their PCBs more reliable, but they probably choose not to because it would cost them more, reducing their profits and impacting future spare parts sales.

P.S. I've just noticed your forum name. If you really do fit only Ideal boilers, that would go some way to explain why you have so many failures. If you want a second opinion then I suggest you go ask the gas fitters what they think about Ideal.

 

[onlyfitidealboilers]

Is it the windings that fuse together causing voltage on the neutral back to the pcb that makes it blow??

just trying to get a better understanding of it.

i fit lots of boilers but i put my user name like this as it winds the gas fitters up!!!

 

[flameport]

If a component such as a pump fails and causes a short circuit, the current which flows will typically be very large, hundreds or even thousands of amps. This current is what melts the fuse and disconnects the power, so it only flows for a fraction of a second.

Unfortunately that same current is also very good at destroying electronic components and melting the tracks on circuit boards.

 

[ericmark]

Only a fuse can protect a semi-conductor a MCB is not fast enough. We had some problems with a machine using heaters in that the contactors were in and out so many times a day they where it seemed for ever needing changing. So we changed the contactor for a semi-conductor model. But as you have found when the heaters went short circuit it killed the semi-conductors as well. Cure was to swap MCB's for semi-conductor fuses after swap heaters did not take out the contactor.
We also had a second problem in that we had to fit E-Stop relays (Contactors) as can't use semi-conductor devices to isolate.
Good manufactures would include fuses built into the PCB however all too often people are unaware that special semi-conductor fuses have been fitted and the item stops working and they see a 1 amp fuse blown and change it for one same physical size and amps but not semi-conductor rated.
We know that where dimmer switches are used with lights we should use a fuse not a MCB but to find a consumer unit with a fuse for the lights is very rare. And if you ever remember life before MCB's changing a fuse is often a problem as rare for there to be spares. In theory every bulb should have built in fuse but many cheap ones don't so you need to change dimmer switch with bulb.

 

[ban-all-sheds]

i put my user name like this as it winds the gas fitters up!!!

Please go away and don't come back until you have grown up.

 

[bernardgreen]

why does this happen..

i fit loads of new pcbs because other parts like the fan or a pump blows them

the pcb has fuse protection, so why does it blow the pcb..

Often the PCB is rendered "out of action" because it has not been designed to cope with failure of other parts. Relay contacts weld before the fuse blows because the cheapest possible relay is used. Solder joints fail due to vibration of leads and heavy components being held on the PCB only by the solder joints. The list is quite long.

The fuse is primarily there to prevent too much damage occuring when something on the board fails.

As someone who often designs PCBs as part of my job I am appalled by the quality of the PCBs in many domestic gas boilers.

 

[ericmark]

i put my user name like this as it winds the gas fitters up!!!

Please go away and don't come back until you have grown up.

And this from someone who calls himself Ban-all-sheds? Thought you two would get on well together?

 

[ban-all-sheds]

I didn't choose my ID to wind people up.

 

[electronicsuk]

I didn't choose my ID to wind people up.

I'm sure you had a signature that would have wound the plumbers up not so long back, though.

 

[ban-all-sheds]

It probably did wind up the lazy useless lying ones, but it wasn't designed to do so - it was designed to warn people to look elsewhere for plumbing advice because of the endemic lying enshrined in the practices of that forum.

 

[onlyfitidealboilers]

i put my user name like this as it winds the gas fitters up!!!

Please go away and don't come back until you have grown up.

shut up you, you misrable old git.