Stuck on PCB for extractor hood. Can an expert help?

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OK, so my TEKA extractor hood stopped working. I'm no expert but I pulled out the PCB and saw that the circuit board had blown.

I think I have also found a replacement part but I'm a bit worried. The wiring coming into the PCB isn't in a handy plug - it is all soldered onto the board. This would be a job beyond me. Surely it shouldn't be that hard, and I am missing something. The board blew once before when it was under warranty, and a engineer replaced it. I don't remember him doing any soldering.

As you can see from the pictures, the cables disappear into the unit.

Any help greatly appreciated!

Thanks!

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Does the new pcb come with wiring attached? There might be plugs on the other ends of the cables.

If not, soldering, or paying someone to fix it seems like your best bet
 
I'm not sure exactly what you are asking.

You won't be able to do any repairs without soldering.
 
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That PCB just looks like it has 4 switches and a neon (plus its resister mounted on it) There is not much to 'blow' In addition all the marks are on the reverse side of the board. Centred around a solder joint that appears to have blown away. I would speculate that the board has simply come into contact with something earthed. The solder on that joint has been blown away and there will be a fuse that has blown somewhere. What is confusing is that the joint looks like it is on the incomming neutral... so the polarity of the supply needs to be checked
 
That PCB just looks like it has 4 switches and a neon (plus its resister mounted on it) There is not much to 'blow' In addition all the marks are on the reverse side of the board. Centred around a solder joint that appears to have blown away. I would speculate that the board has simply come into contact with something earthed. The solder on that joint has been blown away and there will be a fuse that has blown somewhere. What is confusing is that the joint looks like it is on the incomming neutral... so the polarity of the supply needs to be checked

So you think I could resolder the one 'blown' joint or is the PCB knackered?
 
I've watched a few youtube videos on replacing a PCB. None of them involve soldering! This one for instance. Exact same issue, but the new PCB just plugs in.
Yes, but yours doesn't.

Why would they make a part that is prone to problems such a big job to replace?
Probably cheaper. It's not really a big job.

You likely don't really need a new one.
It's just connections which could be repaired and if there are any blown tracks they could be replaced with wires..
 
[QUOTE="spankybuilt]

So you think I could resolder the one 'blown' joint or is the PCB knackered?[/QUOTE]


For sure. Just clean the board up a little from where it has gone pop, to prevent anything flashing over. Use a a solvent thats safe on pcbs such as isopropyl alcohol and a cheap tooth brush to do so. Allow IPA to evaporate before switching on

To solder it. Imbolise the baord so it doesn't flap around. Heat one side of the joint with the iron (allow iron to heat up first) and keep trying to feed the solder in the other side, when it melts around the joint, take the iron away and make sure the board and cable doesn't move for about 20 secs to allow it to cool properly. Best watch you-tube videos on soldering first!
 
^Agreed.
What is confusing is that the joint looks like it is on the incomming neutral... so the polarity of the supply needs to be checked
The polarity won't make any difference.

This type of problem occurs most often when one of the cooker hood bulbs blows and there is a 13A instead of 3A fuse in the supply.
 
^Agreed.
What is confusing is that the joint looks like it is on the incomming neutral... so the polarity of the supply needs to be checked
The polarity won't make any difference.

?

If a board comes into contact with an earthed metal case, then its going to be the connection that is connected to live, not neutral that will end up with flash marks around ti!
 
The board is in a plastic enclosure. The cooker hoods I have installed in the last 4 years have all been double insulated. My money is on the joint failing due to poor assembly leading to a high resistance joint. The blast being it finally giving up due to something else, which form the last three I have had to repair has been the surge from a lamp blowing. Sometimes it blows the tracks off of the PCB if a 13A fuse is used!:eek:
 
That looks like a dry joint probably due to lead free solder so best to use leaded solder to repair it I see all the time on modern equipment.

Andy
 
The board is in a plastic enclosure. The cooker hoods I have installed in the last 4 years have all been double insulated. My money is on the joint failing due to poor assembly leading to a high resistance joint. The blast being it finally giving up due to something else, which form the last three I have had to repair has been the surge from a lamp blowing. Sometimes it blows the tracks off of the PCB if a 13A fuse is used!:eek:

Looking at the construction, it seems you must be right.

Looking at the board on its own, looked like a clear case of "brushed against something earthed"

OP, The advice still stands, just clean the board up and re-solder. If you have a maplin nearby then something like this http://www.maplin.co.uk/p/antex-18w-mains-powered-soldering-iron-fy62s is well suited for general repairs such as this. You'll need some electronics solder as well (leaded if you can get it)
 
I have repaired tracks on these PCBs a few times now. Just clean it up and bridge the links with wire.
 

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