UPS / Fan Replacement

[Ricotta Elmar]

hey guys i have a eaton 9px3000irt3u ups, i bought it 2nd hand, what i didnt know was how loud it was with the fans inside, i tried replacing the fans to quiet once, they do spin up fine but the ups gives fan alarm and wont turn on the groups, do anyone know how to  trick the ups and replace fans to quiet fans ? i dont know how these kind of fans work or how it monitors the fans, it probaly is power draw somepeople say to me because a ups dont read rpm  but it uses a 3 pin fan conector

 

these fans are inside but there is no doc or something abotu the fans so it is quite difficult to find out how these fans work

[RAS_3885]

3 hours ago, WesleyNL said:

hey guys i have a eaton 9px3000irt3u ups, i bought it 2nd hand, what i didnt know was how loud it was with the fans inside, i tried replacing the fans to quiet once, they do spin up fine but the ups gives fan alarm and wont turn on the groups, do anyone know how to  trick the ups and replace fans to quiet fans ? i dont know how these kind of fans work or how it monitors the fans, it probaly is power draw somepeople say to me because a ups dont read rpm  but it uses a 3 pin fan conector

 

these fans are inside but there is no doc or something abotu the fans so it is quite difficult to find out how these fans work

 

It looks to be this fan.

 

https://www.mouser.com/ProductDetail/NMB-Technologies/08025SA-12P-EL-00?qs=XN%2Belh2ZYYb9WrSP3%2BTlqA%3D%3D

 

It calls out something called a locked rotor sensor, which seems to be an alternative to RPM monitoring to detect if a fan is spinning or not. Not sure exactly how it works, but given the fan has a significantly higher current rating than a comparable size and flow from a brand like Noctua (0.30 A for your fan, 0.07 A from a Noctua equivalent) I'm guessing the internal resistance of your new fan is significantly lower and causing the UPS to set the error.

 

If you're electrically handy you could probably wire in a resistor to trick the UPS into not setting the fan error.

[Ricotta Elmar]

if i knew how, and where i could  solder that resistor to trick it i would be happy, bcuz, this ups use 2 of those fans in a air duct

 

i ahve been looking for support on this mather, eaton won't say,

 

i asked noctua to they said maybe the "NF A8 FLX" or "NF-A8 FLX"

 

also , it is not that one i have " AL"  not  "EL"

 

i tried 2 of these

 

https://www.arctic.ac/eu_en/f8-silent.html

[Ricotta Elmar]

i checked one of these ups fans in pc, it dont read rpm but it do work, so i guess rpm wont work ?

[W-L]

6 hours ago, WesleyNL said:

i checked one of these ups fans in pc, it dont read rpm but it do work, so i guess rpm wont work ?

As Ras has said since it's a locked rotor sensor fan all it has is a signal back to the UPS either a high or low to indicate the fan is being obstructed or has stopped spinning for another reason. 

 

The easiest would be to look for locked rotor replacements since they are readily available from places like Digi key, however if you want to test using a bench top PSU you can probe off the third leg and check to see if it's providing a high or low voltage back to the UPS. From that you can determine if you just need some voltage going back through the third leg or a pull down resistor. 

[Ricotta Elmar]

so i have to connect the fan to pc again and see if 3rd leg give a signal on multimeter

 

i hope there are silent fans with locked rotor

 

ok i tested it on a adapter

i don't know ehre the resistance come from,

but if i touch it it jumps to 13v while it is not even powered and as you see it shows a lil signal probaly of 0.05v dont know if the multimeter is broken or not,  when i have it wired up as this is shows some voltage even if not powered

here is a short video how not to do it but heck

https://files.catbox.moe/i8m20m.mp4

but this doesn't explain why i get fan fail if i don't connect that pin,

i readed on a page to connect the pin from the board to ground but that didn't work, i got fan fail,

but i don't see any readings when it spins up unless it is so fast that multimeter don't show it

 

maby i do the measuring wrong i don't know

[W-L]

7 hours ago, WesleyNL said:

so i have to connect the fan to pc again and see if 3rd leg give a signal on multimeter

 

i hope there are silent fans with locked rotor

 

ok i tested it on a adapter

i don't know ehre the resistance come from,

but if i touch it it jumps to 13v while it is not even powered and as you see it shows a lil signal probaly of 0.05v dont know if the multimeter is broken or not,  when i have it wired up as this is shows some voltage even if not powered

here is a short video how not to do it but heck

https://files.catbox.moe/i8m20m.mp4

but this doesn't explain why i get fan fail if i don't connect that pin,

i readed on a page to connect the pin from the board to ground but that didn't work, i got fan fail,

but i don't see any readings when it spins up unless it is so fast that multimeter don't show it

 

maby i do the measuring wrong i don't know

It looks like your fan when the rotor is stopped provides a high signal of 1.5V back to the system from a physical obstruction, in theory it should be alright to leave the signal line disconnected but it might need some resistance to trick it into thinking the singal circuit is connected, unless it's a more complex signal being sent back to the UPS itself. You can try using a small resistor to see if it helps.

 

It may be easier to try and get your hands on an equivalent locked rotor fan, they do make some silent version. For example, just note the lower airflow capability:

https://www.mouser.ca/ProductDetail/Sanyo-Denki/109R0812L4D011?qs=Ldb7c5mTB16rL2SkaFL2NA%3D%3D

 

[Ricotta Elmar]

need to look if i can find a resistor of 40ohms

 

intressing 20db x2  beter than these  loud fans

 

 

[Ricotta Elmar]

sweet i done it guys, though fans are still anying but way less i put tripple 30ohm resistors in serial,

abt a drop to 4.85v if i rember coerrectly,

not pro work but hey,

i glued them together,

putted heatshrink arround it and cnected them, fan fail don't whine,

 

good thing this psu starts fans with a boost,

bcause i doubt the fans would spin up witn < 5v

 

n i guess these resistors would work fine