hp t750 g4 ups - fan too noisy and never stops

[olm1]

Hi, I´m using a hp t750 g4 ups since a couple of days (newly bought). After connecting the ups to AC power source the fan sarted to run (guess a normal procedure) - but since then it is running and running and running since days although the battery pack is fully loaded. The noise of this fan is driving me crazy. What can I do to shut down the fan (aside killing the ups)? Do not know this problem from the former ups (a t750 G2) I used before - there the fan started only during a battery charging period and stopped after a couple of hours.

Thx for your support.

[vbezhenar]

I have the same problem. I bought this UPS for home server, but fans are just unacceptably loud for home, even in "off" state. Very disappointing purchase. I'm considering to cut fan wires or reduce their speed with resistor or replace fans with silent alternatives, but may be there's better alternative.

[olm1]

Yes, indeed  a very disappointing purchase.

Meanwhile I contacted the hpe customer service and they sent me a replacement to test (great support; nothing to say anything bad). But same problem with the replacement device - the fan was noisy as ever (nearly around 60 dB in front as well behind the UPS; hey hpe-guys - this is really too much).

So I had the same idea to unplug the fan or to mount a separate switch. So I opened the housing of my own UPS (uups - lost the warranty but honestly f***** off) and figuered out the following: a) the fan is connected by a 3-pin mini plug on the main board - easy to unplug. b) There are 3 wires to the fan: red, black and yellow - the last one is unfortunately for error checking purposes: c) After 15 sec. after unplugging the fan the UPS quits it by a permanent beep (and the display shows "fan" as error message), so I thought about a circuit with an electrical resistance to bypass this; but: d) on the main board there is at least 1 load transistor (with cooling ribs) getting pretty warm immediately (at least too hot for my fingers while touching). Guess that this is the reason the fan has to run permanently (and I didn´t find any electronic supplement circuit or temperature measurement to operate the fan).

That´s it. I returned the replacement, banished my own noisemaker into the cellar (maybe will use it again for my NAS in the future but far away from my desk or use it for target practices) and bought a new competing product (3 letters; starts with an "A" and stopps with a "C") - so great and relaxing to work next to it and nothing to hear except the klicks of my keyboard :-)