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Bypass PCB in cooker hood?

Does what it says on the tin
Mike4
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Re: Bypass PCB in cooker hood?

#402227

Postby Mike4 » April 7th, 2021, 10:45 am

Snorvey wrote:The PCB blew in my cooker hood back in January and I've been struggling to find a replacement. I have located and ordered one from a company who said they had on in stock, but it turns out they didnt. Now I get a weekly email from them telling me how they are still trying to secure stock and thank you for my patience etc etc.

After stripping it back to remove the PCB it all looks pretty simple in there and I'm wondering. Is it possible to bypass the PCB and just have a simple fused on off switch? I'm not all that bothered about the lights etc. Just the extractor and a single speed would be fine.

I'd get an electrician in to do the work.


It's INSANE, the number of appliances containing unnecessary, cheap and unreliable PCBs nowadays. The rot started with washing machines about 20 years ago.

But to answer your question, the fan in your cooker hood almost certainly runs on plain vanilla 230Vac, If true and if you are happy with it running flat out all the time when ON, yes your sparky can easily bypass everything inside it and give you a switch on the wall to turn it on and off.

GrahamPlatt
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Re: Bypass PCB in cooker hood?

#402237

Postby GrahamPlatt » April 7th, 2021, 11:03 am

Might even be able to put a rheostat in (a “dimmer switch”) and have fine control of the fan speed.

bungeejumper
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Re: Bypass PCB in cooker hood?

#402266

Postby bungeejumper » April 7th, 2021, 12:08 pm

I'd take a look at the cost of a new cooker hood - there was a pretty good choice below £100 the last time I looked - and compare with the cost of getting a sparky in to hot-wire it. Assuming he's willing to do that, of course. :?

Speaking of hot-wiring, I did tangle with a PCB from a cooker hood once - one of the speed switches was playing up and I wanted to bypass it - but the damn thing turned out to be too fragile for an amateur to repair. Having been made in a solder bath, with the thinnest possible metal on the bus, it basically melted as soon as I went near it with even the finest soldering iron I possessed. Enough heat to melt the solder was enough to mangle the board. Much cursing, and off to buy another unit. Haven't regretted it. ;)

BJ

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Re: Bypass PCB in cooker hood?

#402306

Postby pochisoldi » April 7th, 2021, 1:55 pm

GrahamPlatt wrote:Might even be able to put a rheostat in (a “dimmer switch”) and have fine control of the fan speed.


Not guaranteed to work with AC motors - depends on the type of motor.
Also note that most motors are inductive, and old school dimmer switches expect a resistive load, and an inductive load may cause misbehaviour of overload.

If I were in the OP's position, I'd be examining the control PCB to see where the damage was, then pick one of the following

1. Physical damage to the PCB would be repaired with suitably thick bits of wire/copped soldered to the tracks (and varnished over for protection).
2. Obviously damaged component(s): replace
3. Test any switches for continuity: replace as req.
4. Turn the PCB into a circuit diagram and then analyse further
5. Hard wire it to run at full speed
6. Move the hood into the workshop for extracting soldering fumes, block the vent hole in the kitchen wall and open the window as required....

bungeejumper
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Re: Bypass PCB in cooker hood?

#402318

Postby bungeejumper » April 7th, 2021, 2:22 pm

Not an entirely flippant question, but how do insurance companies look upon such home-made repairs? You could probably sidestep the PCB and run the fan directly without too much danger or difficulty, but would that be likely to result in a refused claim if the fire brigade noticed it?

Speaking of which, the one in my daughter's new home turned out to be running on a 13 amp fuse. Presumably they'd run out of two inch nails? :)

BJ

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Re: Bypass PCB in cooker hood?

#402333

Postby csearle » April 7th, 2021, 3:12 pm

Snorvey wrote:The PCB blew in my cooker hood back in January and I've been struggling to find a replacement. I have located and ordered one from a company who said they had on in stock, but it turns out they didnt. Now I get a weekly email from them telling me how they are still trying to secure stock and thank you for my patience etc etc.

After stripping it back to remove the PCB it all looks pretty simple in there and I'm wondering. Is it possible to bypass the PCB and just have a simple fused on off switch? I'm not all that bothered about the lights etc. Just the extractor and a single speed would be fine.

I'd get an electrician in to do the work.
I repaired one of these in January after doing a test/inspection of a rental flat. The module with the switches on the front had stopped working. In it there was a tiny power supply unit, PSU, to run the electronics and four relays that switched line voltage to one of three (I think) switched wires running to the fan and one to the light. I bought a replacement module from a place called Doncaster Kitchens for £135 delivered.

Chris
PS I came across Doncaster Kitchens by emailing the hood manufacturer enquiring about spare parts.

Edit: I suspected that the PSU had failed and offered to either replace the hood, replace the module, or repair the module as the PSU components were discrete. The client chose the middle option.

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Re: Bypass PCB in cooker hood?

#402343

Postby bungeejumper » April 7th, 2021, 3:36 pm

ReallyVeryFoolish wrote:It's exactly that fact (insurance company loss adjuster looking for exactly that kind of thing) which stops me doing stuff like that. For a new £100 extractor fan, it isn't worth the risk.

Thanks for that. So how does it work? If you found something in an appliance that had been significantly altered from the manufacturer's spec, but safely and competently, would you still raise the black flag about a claim? (Or reduce the payout?)

1) If the appliance had caused the incident;
2) If it hadn't but you'd noticed it anyway?

We pay out a lot of money for the electrical inspections on our rental property, and we rather like it when they find wrongly-rated fuses and stuff because it means they're being thorough. (It's just a pity that they didn't notice all the illegal daisy-chained spurs that our last tenant had installed. :( But maybe those are hard to spot anyway?)

BJ


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