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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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DC Fans - weird problem
I have a good quality on-line Uninterruptible Power Supply with 2 fans.
One of the fans is too noisy, so I'm wanting to replace it. I've purchased 4 fans, 2 each of 2 different types; Sunon and Dick Smith Electronics. None of the new fans will work properly. The Sunon fans wiggle, and will spin if I set them going with my finger. The Dick Smith fans won't spin at all. The original fan (which still works, therefore, the circuit is OK), is: Minebea Model 3110Gl-B4W-B44 12V DC 0.26A Brushless The Sunon fans (which I've now returned to the shop) were 12V DC 0.26W (probably a misprint and were actually 0.26A) The Dick Smith fans are model Y8507 and simply say 12 Volt. These are sleeve bearings. The voltage measured with a Dick Smith fan connected is about 3V and with the original Minebea fan connected (and spinning) it's 10.7V. I'm completely confused. Any help appreciated. thanks, RR |
#2
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DC Fans - weird problem
"RR" wrote in message ... I have a good quality on-line Uninterruptible Power Supply with 2 fans. One of the fans is too noisy, so I'm wanting to replace it. I've purchased 4 fans, 2 each of 2 different types; Sunon and Dick Smith Electronics. None of the new fans will work properly. The Sunon fans wiggle, and will spin if I set them going with my finger. The Dick Smith fans won't spin at all. The original fan (which still works, therefore, the circuit is OK), is: Minebea Model 3110Gl-B4W-B44 12V DC 0.26A Brushless The Sunon fans (which I've now returned to the shop) were 12V DC 0.26W (probably a misprint and were actually 0.26A) The Dick Smith fans are model Y8507 and simply say 12 Volt. These are sleeve bearings. The voltage measured with a Dick Smith fan connected is about 3V and with the original Minebea fan connected (and spinning) it's 10.7V. I'm completely confused. Any help appreciated. thanks, RR try all the 12 volt fans on a 12 volt power supply or car battery (or the battery in the UPS assuming its 12.6V). if they work the problem is the source voltage. maybe a flaky resistor or part in series make sure the fans do not have some kind of whackey diode built into them which is hooked up backwards. |
#3
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DC Fans - weird problem
"tim perry" wrote in message . .. try all the 12 volt fans on a 12 volt power supply or car battery (or the battery in the UPS assuming its 12.6V). if they work the problem is the source voltage. maybe a flaky resistor or part in series Thanks, they all work fine outside the UPS. So, it's definitely the source circuit? The UPS has two fans with separate connectors. Is it likely that the two connectors would be on the same circuit (which might be flaky)? I guess if they are separate circuits then the same problem wouldn't be on both connectors. make sure the fans do not have some kind of whackey diode built into them which is hooked up backwards. Are you suggesting a manufacturing fault in the fans? If so, then it's not likely with 4 fans from 2 different manufacturers. thanks again, RR |
#4
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DC Fans - weird problem
RR wrote:
I have a good quality on-line Uninterruptible Power Supply with 2 fans. One of the fans is too noisy, so I'm wanting to replace it. I've purchased 4 fans, 2 each of 2 different types; Sunon and Dick Smith Electronics. None of the new fans will work properly. The Sunon fans wiggle, and will spin if I set them going with my finger. The Dick Smith fans won't spin at all. The original fan (which still works, therefore, the circuit is OK), is: Minebea Model 3110Gl-B4W-B44 12V DC 0.26A Brushless The Sunon fans (which I've now returned to the shop) were 12V DC 0.26W (probably a misprint and were actually 0.26A) The Dick Smith fans are model Y8507 and simply say 12 Volt. These are sleeve bearings. The voltage measured with a Dick Smith fan connected is about 3V and with the original Minebea fan connected (and spinning) it's 10.7V. I'm completely confused. Any help appreciated. thanks, RR Are you sure the originals were DC fans and not AC? |
#5
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DC Fans - weird problem
The biggest problem I have with fans is the lubricant is not
permanent. remove the label and drop one drop of oil on the shaft. The old one will run for another year - usually. |
#6
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DC Fans - weird problem
The point of a UPS is to improve reliability. Why leave something in
that you know will fail, and will require you to shut down the system and solve the problem again? Cher wrote: The biggest problem I have with fans is the lubricant is not permanent. remove the label and drop one drop of oil on the shaft. The old one will run for another year - usually. |
#7
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DC Fans - weird problem
"RR" schreef in bericht
... I guess if they are separate circuits then the same problem wouldn't be on both connectors. Just a guess, maybe the 2 fans are in series connected to a 24 supply? I would never design it like that, but never know in this crazy world. Al |
#8
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DC Fans - weird problem
"CJT" wrote in message ... Are you sure the originals were DC fans and not AC? The label says DC and my multimeter reads the DC on the lines. thanks, RR |
#9
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DC Fans - weird problem
"JW" wrote in message ... On Fri, 12 Sep 2003 05:49:44 GMT "RR" wrote in Message id: : None of the new fans will work properly. The Sunon fans wiggle, and will spin if I set them going with my finger. The Dick Smith fans won't spin at all. Did you try reversing the leads? Yes, that didn't help either. thanks, RR |
#10
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DC Fans - weird problem
"Cher" wrote in message ... The biggest problem I have with fans is the lubricant is not permanent. remove the label and drop one drop of oil on the shaft. The old one will run for another year - usually. Good idea. But since it is on its way out, I'd prefer to replace it. A colleague who knows more about electronics than I thought that the UPS circuitry might be using current/voltage to control the speed of the fans. Therefore, only specific types of fans will work. However, when I called Farnell Components, their tech guy had never heard of that on a two wire system. thanks, RR |
#12
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DC Fans - weird problem
On Fri, 12 Sep 2003 22:31:04 +0200, "The Al Bundy"
wrote: "RR" schreef in bericht ... I guess if they are separate circuits then the same problem wouldn't be on both connectors. Just a guess, maybe the 2 fans are in series connected to a 24 supply? I would never design it like that, but never know in this crazy world. I've run into a few setups that put fans in series. I suspect this is very likely if the UPS has a pair of 12volt batteries in series. The bad fan would try to draw more current and hence get less voltage. Does the other fan run with the first disconnected? What's it's voltage look lke? |
#13
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DC Fans - weird problem
OK, just trying to give you some field expedience. If you don't want
to do it twice - and I have seen oiled fans last longer than a new one - More than likely the fan connector is protected by a current limit resistor. That means the more current you draw the less voltage you get. A dead short on the pins should not cause burnt traces on the board. The downside is that a fan with a higher current draw will be trying to run on less voltage to the point that it may not function at all or may only function if you start it first - max current drain. If you have a few assorted resistors you can use them to determine a usable current rating for the fan using a little Ohm's law. Or just get another fan with the same rating as the old one. On Fri, 12 Sep 2003 22:36:27 GMT, "RR" wrote: "Cher" wrote in message .. . The biggest problem I have with fans is the lubricant is not permanent. remove the label and drop one drop of oil on the shaft. The old one will run for another year - usually. Good idea. But since it is on its way out, I'd prefer to replace it. A colleague who knows more about electronics than I thought that the UPS circuitry might be using current/voltage to control the speed of the fans. Therefore, only specific types of fans will work. However, when I called Farnell Components, their tech guy had never heard of that on a two wire system. thanks, RR |
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