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Old Jul 10, 2012, 10:59 PM
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Australia, NSW, Rydalmere
Joined Feb 2010
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Originally Posted by Dusey52 View Post
Use caution when disabling the fan. There's a post here on RC Groups (possibly this thread) by someone that ran a data center. He said he experienced a number of failures with early versions of the power supply that turned the fan off when not needed. Long story short, they racked up a bunch of these and plugged them in but left them OFF for a couple of weeks. When it came time to power up the servers a number of them had dead power supplies. The replacement power supplies all had fans that slowed down but didn't shut completely off. Will this affect our application? Who knows, but there is risk.
Yep, that was me. 15-20 servers powered off in a rack (ie. no air flow through the server) and 2 x PSU's in each server generating 35-50w (the 5v 7A standby = 35w) each, a lot of them overheated and failed.

The PSU's were then modified to slowly turn the fan to keep at least some air flow going through them - that is why the fan slowly turns when connected to AC power.

Keep a close eye on temps if you plan to run with no fans turning. If you have seen inside these PSU's, there are a lot of components in a very small package - they rely on the airflow to survive.

Cheers
whitedg
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Old Jul 11, 2012, 08:33 AM
jocanon's Avatar
United States, AZ, Gilbert
Joined Jul 2010
511 Posts
Quote:
Originally Posted by Dusey52 View Post
Use caution when disabling the fan. There's a post here on RC Groups (possibly this thread) by someone that ran a data center. He said he experienced a number of failures with early versions of the power supply that turned the fan off when not needed. Long story short, they racked up a bunch of these and plugged them in but left them OFF for a couple of weeks. When it came time to power up the servers a number of them had dead power supplies. The replacement power supplies all had fans that slowed down but didn't shut completely off. Will this affect our application? Who knows, but there is risk.
Duly noted. I remember reading that post as well. I wonder though if the PSUs were heating up and the heat is what caused the failure. Since my circuit is heat driven it seems like that should not be a problem because if it starts to heat up, the fan will kick in immediately and ramp up rpm in direct relation to heat increase.

The only thing I see as an issue (other than the tach problem which I still need to fix) is making sure I get the tempurature sensor in the "right" place, if there is one "right" place. Any thoughts on this question are welcom. I am thinking the right place might be the heat sink...but if so which one, there are a couple in there? I can run it and just see what part heats up first. Maybe the only way to know if it will work is just to build it and test it out.
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Old Jul 11, 2012, 08:35 AM
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Originally Posted by xandrios View Post
Thanks, I'll check it out.
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Old Jul 11, 2012, 08:38 AM
Stop scaring my donkey!
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I substituted some low speed fans, that are near-silent-the measured exhaust temperature never gets above 100 degrees F.
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Old Jul 11, 2012, 08:38 AM
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United States, AZ, Gilbert
Joined Jul 2010
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Quote:
Originally Posted by whitedg View Post
Yep, that was me. 15-20 servers powered off in a rack (ie. no air flow through the server) and 2 x PSU's in each server generating 35-50w (the 5v 7A standby = 35w) each, a lot of them overheated and failed.

The PSU's were then modified to slowly turn the fan to keep at least some air flow going through them - that is why the fan slowly turns when connected to AC power.

Keep a close eye on temps if you plan to run with no fans turning. If you have seen inside these PSU's, there are a lot of components in a very small package - they rely on the airflow to survive.

Cheers
whitedg
It might be a good idea to just set the fan to minimal speed instead of shutting it completly off then. Even if I do that, I think I still like the temperature controlled circuit because it is more responsive than simply connecting pins 4 & 8. I can adjust the pot in my circuit to make the fan slow down but never go off. I'll play around with it and see. It might still be possible to shut it all the way down as long as the fan kicks in at some point as it heats up with out any load.
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Old Jul 11, 2012, 08:41 AM
Stop scaring my donkey!
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Did FMA send you a new charger?
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Old Jul 11, 2012, 08:45 AM
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United States, AZ, Gilbert
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Originally Posted by JohnathanSwift View Post
Did FMA send you a new charger?
He tried, but they are out of stock until July 20 or 23, I can't remember. Oh well, I have enough to keep me busy till then
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Old Jul 11, 2012, 08:47 AM
Stop scaring my donkey!
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Well, that was certainly a snake-bitten transaction.

The PL 8 is constantly on backorder, so I suppose it is a very popular charger: I have two of them!
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Old Jul 11, 2012, 08:53 AM
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United States, AZ, Gilbert
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Originally Posted by JohnathanSwift View Post
The PL 8 is constantly on backorder, so I suppose it is a very popular charger: I have two of them!
I am taking your word for it, it looks like it will be a great charger. I guess good things come to those who wait, right?
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Old Jul 11, 2012, 05:35 PM
Use the 4S Luke
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USA, TX, Euless
Joined Aug 2003
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JohanathanSwift - Where do you live? (City,State)

While testing power supplies for my business, I was at my flying field and set up a pair powered up fans running and no load then another pair charging two 6S 5,000 at 20A each. I was measuring temps and found no difference in case temp. Both were running 114degF. It was a hot day near 100 degF but I could not figure out how the unloaded power supplies were running so hot. I pointed my IR thermometer upward to the roof of the 'shed' we use for shade. It read 142degF! I was standing in a giant easy bake oven.

The point is that before you contemplate slowing down the fans, remember how you intend to use the power supplies. I would hate to burn one up just because I thought the fan was noisy.
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Last edited by feathermerchant; Jul 11, 2012 at 09:18 PM.
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Old Jul 12, 2012, 02:15 AM
Steven
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United States, CT, East Hartford
Joined May 2010
504 Posts
Hey whitedg,

were these early versions of the DPS-600PB that fried?
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Old Jul 12, 2012, 06:58 AM
Stop scaring my donkey!
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Feather is right: I only use mine indoors, where it is always 72 degrees F!
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Old Jul 12, 2012, 08:17 AM
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United States, AZ, Gilbert
Joined Jul 2010
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Quote:
Originally Posted by feathermerchant View Post
JohanathanSwift - Where do you live? (City,State)

While testing power supplies for my business, I was at my flying field and set up a pair powered up fans running and no load then another pair charging two 6S 5,000 at 20A each. I was measuring temps and found no difference in case temp. Both were running 114degF. It was a hot day near 100 degF but I could not figure out how the unloaded power supplies were running so hot. I pointed my IR thermometer upward to the roof of the 'shed' we use for shade. It read 142degF! I was standing in a giant easy bake oven.

The point is that before you contemplate slowing down the fans, remember how you intend to use the power supplies. I would hate to burn one up just because I thought the fan was noisy.
Wouldn't a temperature sensing fan solve that problem? I mean, with a temperature sensing circuit if it was a hot day and the PSU was running hot, the fan would simply rev up to full power and stay there until the PSU was no longer hot. I think where you would have an issue is if you just short pin 4 to 8 because that is NOT temperature controlled.
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Last edited by jocanon; Jul 12, 2012 at 08:40 AM.
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Old Jul 12, 2012, 08:48 AM
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United States, AZ, Gilbert
Joined Jul 2010
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It worked! Thanks for the link xandrios. I successfully created a temperature controlled fan circuit and a 555 timer to trick the DPS-600PB into thinking the fan is always running. I found out that I could wire the circuit directly through the regular fan plug (about 9.5 volts DC), but then the fan makes a faint high pitch squeal when it is slowing down, I think because you can hear the buzz from the PWM frequency. I connected the fan to 12 volts DC instead and the sound went away, complete silence at every speed other than the faint noise of the fan blades cutting through the wind, nice .

Interesting to note, the 555 timer is not needed if the fan never completely stops. I decreased the resistance in the pot and made the fan come on at room temperature, once I did that, the PSU worked fine, because it was getting a tach pulse, and the fan was still temperature controlled. I may end up tuning it so that the fan never stops, depending on results of testing, but I think I will still include the 555 timer just in case. I mean, if the PSU is being run on a very cold day, like say outside on a cold winter day with a generator, and it is running very cold so no need for the fan when it is first powered up you would not even be able to get the PSU to turn on without the 555 timer circuit installed.

Here is the tempurature controlled fan in action. Right now the temperature sensitivity is very sensitive, all I have to do is touch the thermistor and it revs up. I need to add another resistor to the circuit at R1 (per schematic in second link) to get a wider temperature range. So, there is still some fine tuning left to do, but the general idea works!

DPS-600PB temperature controlled fan (1 min 59 sec)


This is where I got the information to build the temperature controlled circuit if anyone is interested:

http://www.electro-tech-online.com/c...an-driver.html

and (duplicate info of above):

http://www.heatsink-guide.com/tempcontrol.htm

see link above in xandrios post for 555 timer.
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Last edited by jocanon; Jul 12, 2012 at 06:36 PM.
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Old Jul 12, 2012, 06:51 PM
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Australia, NSW, Rydalmere
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Quote:
Originally Posted by xandrios View Post
Hey whitedg,

were these early versions of the DPS-600PB that fried?
Yep, it was from our first batch of G4's. I think the issues was very quickly rectified, and HP swapped out all the PSU's from these servers.

Cheers
whitedg
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