UPS Wattage

[johnnymg]

Lets talk about your bathroom fan. Make and model please.

I have installed around 30 bathroom fans and some have motors that need caps to start. They shoot a lot of juice right when you turn the fan on to fire up the motor those caps can be double the voltage for a spilt second to start the fan's motor. If you have an aging cap inside this can be the cause of the sound. If the ground wire is loose on the fan this can be why. How old is the fan 3 or more years of heavy use can be enough to kill the cap.

That's a good line of thought .............. however the speaker/headphone noise is still there when the UPS is on bats. If that is REALLY IS the case, then it has to be EMI.

JohnG

 

[philipma1957]

emi would come from the fans motor if the cap is over juicing it at startup. The motor is magnetic in nature and if the cap is way over voltage the motor's magnet will send out more emi. Also rfi can be caused from the same problem. If it is rfi a ground will help the rfi bleed off. If it is too much emi it won't be solved with better grounds.

 

[johnnymg]

emi would come from the fans motor if the cap is over juicing it at startup. The motor is magnetic in nature and if the cap is way over voltage the motor's magnet will send out more emi. Also rfi can be caused from the same problem. If it is rfi a ground will help the rfi bleed off. If it is too much emi it won't be solved with better grounds.

It's probably a loud POS "contractor" fan that retailed for $20 and cost <$2 to make. These crap fans are the bane of the building industry. In any case, it's probably a lot cheaper to just replace the fan than shield the MP.

JohnG

 

[nanofrog]

It's probably a loud POS "contractor" fan that retailed for $20 and cost <$2 to make. These crap fans are the bane of the building industry. In any case, it's probably a lot cheaper to just replace the fan than shield the MP.

JohnG

Included audio circuits used on motherboards don't have great noise filtration to begin with, but it's my understanding that the MP's are worse than most (based on other posts, as I've not had access to 2009/10 system).

So the fan may not be a problem (BTW, I'm not accustomed to the el cheapo bath fans having a motor large enough to require startup caps). Better built, more expensive units, perhaps (usually the high airflow units).

Worth checking the fan out though, as a loose wire (ground or otherwise) is a potential safety hazard.

 

[philipma1957]

some common fans with starter caps by common they sell or did sell at lowes and home depot. Nutone ls100 ultra quiet is a fan only part number 2 shows starter cap

http://parts.broan-nutone.com/nutone/Shop?DSP=30115&PCR=1:21000&IID=LS100

Nutone LS50 below same part number 2 is a cap

http://parts.broan-nutone.com/nutone/Shop?DSP=30115&PCR=1:21000&IID=LS50

Nutone LS80 below same part number 2 has a cap

http://parts.broan-nutone.com/nutone/Shop?DSP=30115&PCR=1:21000&IID=LS80

these sold for years in HD and Lowes. If he has one of these and the cap is going if will make pops in audio gear.

 

[nanofrog]

some common fans with starter caps by common they sell or did sell at lowes and home depot. Nutone ls100 ultra quiet is a fan only part number 2 shows starter cap

these sold for years in HD and Lowes. If he has one of these and the cap is going if will make pops in audio gear.

They use the same generic exploded diagram for each though, so I'm uncertain of which units actually use a starter cap or not.

The ones I recall, the motor's didn't appear to be much different than what's in a floor fan (no cap, but this was pre CCFL bulbs ).

There's one thing that come to mind that makes sense though, assuming the start cap is in every unit they make. It's there to minimize the startup for the units that do have lights (presumed CCFL bulb/s + fan, so they mitigated the fan's start current as a means of arc prevention on the switch - thinking in terms of dwellings without arc fault breakers), and they're using the same part to reduce costs (specifically, the metal tab that holds the fan socket). So a cap ends up in every unit, fan only, or fan + light.

Assuming this is what happend, then it will definitely make noise if the cap's going bad.

BTW, do you recall the type (electrolytic, ...)?

 

[philipma1957]

They use the same generic exploded diagram for each though, so I'm uncertain of which units actually use a starter cap or not.

The ones I recall, the motor's didn't appear to be much different than what's in a floor fan (no cap, but this was pre CCFL bulbs ).

There's one thing that come to mind that makes sense though, assuming the start cap is in every unit they make. It's there to minimize the startup for the units that do have lights (presumed CCFL bulb/s + fan, so they mitigated the fan's start current as a means of arc prevention on the switch - thinking in terms of dwellings without arc fault breakers), and they're using the same part to reduce costs (specifically, the metal tab that holds the fan socket). So a cap ends up in every unit, fan only, or fan + light.

Assuming this is what happend, then it will definitely make noise if the cap's going bad.

BTW, do you recall the type (electrolytic, ...)?

I did a lot of them electrolytic. They all use the same cap. color yellow about .8 x .8 x .25 inches I want to say 300 volts. I have a few on hand but in a shed. If he has these models he could have that cap going bad.