How to Fix an Extractor Fan Timer
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- เผยแพร่เมื่อ 12 ธ.ค. 2016
- Those bathroom extractor circuits often pack up in one way or another after some years of use. Like a lot of electronic circuits it's the electrolytic capacitors that are the main culprit. The circuit usually malfunctions by not staying on for very long after the light is turned off. In this one case the fan was gong on and off rapidly when the light was on.
It was fixed by the simple replacement of capacitors as shown.
I used some tantalum capacitors that I had in stock as replacements, but changing them for new ones of the normal electrolytic type should also fix it.
If you want to buy some capacitors, have a look on eBay, for instance 330uF electrolytic capacitors:
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It was the smaller 47uF capacitor on mine as well - symptom was that the fan got slower and slower over the space of a few weeks, eventually just humming but not spinning at all. Disconnecting the two black motor wires from the timer circuit and putting mains onto them proved that the fan was AOK (though was starting to clog with dust and got a good clean).
Glad you fixed it and I could help.
Many thanks for this video, I changed the 47microFarad capacitor and now all is well. I bought 10 of these capacitors on Ebay for £1.15! Saved my money and a fan from landfill. Dead chuffed.
Well done.
Thanks for the video, 2 capacitors replaced and works again amazing. Had actually bought a replacement fan before finding this video, luckily before throwing out the old one this being the third fan I've bought wish I'd known about this could have saved a fortune as the capacitors didn't cost much all in a repair for a couple of pounds instead of the full cost of a fan. At least I now have a spare I can swap out when the new one goes and have spare parts for when this one goes
Thanks for posting this, it helped me fix my identical timer. My fan was running continuously after a lightning strike hit and destroyed a tree across the road. Many houses had their internet hubs and routers destroyed but as far as I know we were the only one with a bathroom fan problem. I saw the large burnt resistor with illegible markings and assumed that was the problem but you told me the specification and like yours mine measured correct. It wasn’t the capacitors either in my case, they looked and measured correct, it was three of the semiconductors, which I could have guessed given it was a high voltage attack. One of the 15v Zenner diodes was shorted. The logic quad nor gates didn’t work and the triac was shorted. The triac caused me the biggest problem as it is marked Z0125, which doesn’t seem to exist. I couldn’t get a Z0110 which is the 25mA trigger one so used a different type of triac which didn’t work at all, so used a Z0109 a 10mA trigger one, which did work. Time will tell how long for.
I drew the circuit out. The AC mains is half rectified and dropped to 15v to power the nor gates, live also goes straight to the motor. Neutral to the motor is controlled by the triac. The switch terminal is somehow connected to turn pins 12/13 low when its live, I don’t understand how this works, something to do with the resistors and one zenner. This turns pin 11 high which charges the 330 uF capacitor, a diode stopping it discharging back through pin 11 when low. This charge is also on pin 9, 8 is always low, making 10 low, which makes 5/6 low and so 4 high. 4 is connected to the gate of the triac which conducts and neutral is connected to the motor and it runs. The capacitor slowly discharges through a fixed and variable resistance, eventually pin 9 goes low turning 10 high so 4 low and the triac turns neutral off.
Thanks for your interesting feedback.
3 years further on and I've had another of these fail, same circuit, this one stopped over running when the light was off then eventually was humming loudly and running slowly. The 22k resistor was brown but tested OK, the fault as with yours was that the two capacitors, 16v 47uF and 330uF had failed, replacement fixed it. Hopefully OK for another 20 years.
Thank you for this video. Our extractor started stuttering recently and I watched this video, bought the components and replaced them just now. Working perfectly for another few years. Cheers!!
Great to hear, well done.
On mine the 47uF capacitor went high ESR, the capacitance actually still measured fine but ESR was around 15 ohm (should be about 2 max). The big 470uF actually tested fine in my case.
Thanks for that, I always assumed the capacitance value decreased over time causing failure but I never actually measured it or esr.
I have been called a cowboy for doing less! ;)
Lol. It may not look pretty with my use of old components! Using new ones would be better. A ‘cowboy;’ repair is one that doesn’t last long, whereas this fix is still working fine over 2 years later.
I am nearly 95% sure that the capacitor has lost capacity over time due to the heat of the resistor. They just dry out over time and you could see that if you compare the old capacitor with a new one using an Oscilloscope. The lower voltage will change the way the board works so I probably would start with the 470uf/16v capacitor to see if that makes a difference.
Heat certainly makes things age faster. There is also the factor that there are many cheap Chinese electrolytic capacitors where the electrolyte formula was copied from a Japanese company but without one vital ingredient meaning that they don’t last very long. A lot of electronics seems to be plaqued by early failure due to these. Even without that factor the electrolyte seem to age and degrade somewhat anyhow, it seems.
How can you set the length of time it runs? Or is it factory set?
Yes normally a small potentiometer on the circuit board which you adjust by a small screwdriver.
@@comeinhandynow thanks, thats helpful.
Where do you buy capacitors? Maplin now shut 🤔
Ebay, RS components, farnell.
The timer on my Addvent fan AVX 100TN packed up recently. On examining the little PCB, it looks pretty much identical to the PCB in the film and it appears that the big resistor has failed due to the blackening underneath it. However I'm not an electronic whizz-kid so there's no way that I'd have the tools or know how to change that resistor. Therefore can anyone out there tell me where I can purchase a new timer PCB which I am competent to replace rather than putting a perfectly good working fan into landfill. The manufacturer say that City Electrical Factors supply those timers to them. On enquiring with CEF they say that they don't. It looks like another case of 'throwing the baby out with the bathwater' encouraging us to continue building greater mountains of plastic refuse, regardless of the impact on the environment.
I know you think you dont have the expertise, but that is only because you haven’t tried it. Get a multimeter that measures resistance (in ohms) and measure that resistor. It may be black but it may still work (have a resistance, as opposed to infinite resistance). My bet is that its the capacitor(s) gone. Get a soldering iron and leaded solder. Practice soldering. It’s not hard. Desolder the capacitors. Replace with new ones from ebay or the like. You may surprise yourself. You’ll gain a soldering iron, some experience, might have some fun fixing stuff and wont have lost much.
Do you have multi-meter? If so just measure the resistance of the resistor to check (22k in my case). Mine also looked cooked and has turned the PCB brown but that's normal, it just runs hot 24/7.