A while back, the noise in my office got to me. I had a computer that was winding up like a formula one racer and a furnace that when on and I am watching a news broadcast makes me turn up the television way too high. So that summer project was to first quiet down the furnace/air conditioner with a new unit from Mitsubishi Electric and then build a new computer with the help of bequiet!.  The silence is golden, until the neighbors start up with leaf blowers, chain saws, and mowers.  Then one evening, I went into the office to check email and I could hear that familiar sound of a computer fan running at full speed. You can read the full article: A Silent bequiet! Upgrade

CyberPowerCome to find out it was not one of the computer fans but the fan inside of my Uninterruptable Power Supply (UPS). Years ago, I switched to using the UPS from CyberPower and have been very pleased with the units and have several of them scattered about the office.  This UPS is one of the larger ones as I wanted to be sure that when I do lose power, I can still keep working for a couple of hours.  In the past, I would get a new unit, install it, plug it in and forget about it until the battery complains that it needs replacing. But this unit, the noise was truly annoying and the first thing I discover is that for this particular unit, the PR1500LCD, there is no guide to checking or replacing the fan.  In fact, when I contacted CyberPower, they tell me there is no information at all or parts available to replace the fan. 

PR1500LCDWith a $549 list price, I really didn’t want to just dump it and get a new unit so like any engineer, I unplugged it, removed the battery, and proceeded to take the case apart. With a shipping weight of 60 pounds, it was not easy to deal with. I was also quite surprised that after four years of sitting near the floor, it was actually pretty clean inside the unit when I finally got the 80mm fan removed.

Nothing blocking it, no dust bunnies, and it looked quite useable.  So, I grabbed another 80mm fan and the first thing I discover is that all of the computer based case fans that I had have three power pins and this one only had two.  Next was to clean the fan, made sure it spun well, and put the system back together again and fired it up and it was nice and quiet.

Taking a closer look I noticed the fan was not spinning at all and when it starts up after a couple of days, would spin rather loud at top speed. So, the fan is either on or off. Next was to see why. Another chat with CyberPower couldn’t answer that. Maybe I needed to update the firmware.

No, but there is software that tells you what is going on with the unit so, download it and now I get into a world of technical stuff only an electrician would love. And before I go too much further, you are right, I don’t need three hours of run time and the next unit will be much smaller and lighter.

UPS Current Status

So, is this a UPS issue, a voltage problem with my house, or a power problem? One question came to mind and that was; how much voltage should be coming out of my wall outlets in my home office?  And does the UPS unit need its voltage input limits reset? Is the UPS unit going bad?

A call to the electrician should give me information about how much voltage should be coming out of my wall outlets. And according to howtolookatahouse.com: the acceptable voltage range of a nominal 120-volt receptacle at between 114 and 126 volts. My electrician and the local power company that I called with the same question went unanswered.

What has been happening is that the UPS detects that the voltage is too high and so lowers the voltage to my equipment.  This is when the fan takes off and wines away. So, is my home office getting too much voltage and is that what is triggering the UPS? When that happens, I check the other UPS units and get readings between 127 volts and 129.6 coming out of my wall outlets.  It is then I see the cryptic message that the output voltage has been lowered to 114 with a “voltage buck”.  See below as to what “voltage buck” is all about.

Voltage Buck

So for the past two weeks, I have been waiting for an answer from either the power company or my electrician and as life would happen, the fan never spun up again and all is quiet in the office.  And of course, the noise was replaced by my neighbor removing three quite large trees from his property so I wonder, did the power company make an adjustment or what? I guess I will wait and see.

Robert Sanborn
November 2021