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Old Oct 22, 2012, 11:00 PM
ancora imparo
jj604's Avatar
Melbourne, Australia
Joined Jul 2005
6,608 Posts
Just for anyone with the same problem:

1) I soldered a standard mains power cord directly to the Power Supply pins on one of mine. Easy to do - just make sure you insulate them properly as they are mains voltage.

2) The wonders of the great Chinese Manufactury will bring you a proper plug to your door for about $5. Do a search for "IEC19 Plug" on Google and look for an eBay or Alibaba Express vendor who will supply in single quantities with free postage.

Here's the one I got mine from.

http://www.ebay.com.au/itm/IEC-320-C...ht_3519wt_1165

(It's the Ozzie eBay page but he ships free to most of the world I'm pretty sure)

If you buy a cable locally it may cost a lot more than the PS did.

John

Quote:
Originally Posted by Seajay_y2k View Post
John,

Thanks for creating this Thread and "How To", I bought the PS off of Fleabay, and it was an easy setup.. this PS easily powers my Hitec X2 charger... The hardest part I had with the conversion was that the Power connection on the PS that I received didn't have a standard connection that I could have used a standard computer Power cord, so I had to make one myself.. Not all that difficult tho..

Thanks again.

Craig.
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Old Oct 22, 2012, 11:04 PM
ancora imparo
jj604's Avatar
Melbourne, Australia
Joined Jul 2005
6,608 Posts
Sounded like a good idea at the time!

Range of adjustment is insufficient to get it to read correctly. I may replace the pot or add a resistance and see if I can make it work. Hardly worth the effort taking it apart seeing as what it costs but it is annoying me.

John
QUOTE=jj604;23074250]
I will try calibrating it and then see how linear it is.

John[/QUOTE]
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Old Oct 22, 2012, 11:37 PM
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So. Cal.
Joined Oct 2004
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John,

FWIW, I had a cheapy current shunt / meter that I got from eBay a good while ago that was also reading quite high. Like you, I could not adjust it within a range that was suitable for my needs. I then hatched an idea to add a parallel conductor to lower the voltage drop and 'adjust' the shunt to the point that it is now very usable in my application and reasonably agrees with both my homebrew shunts and my Medusa Power Analyzer.

Mark
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Old Oct 22, 2012, 11:52 PM
ancora imparo
jj604's Avatar
Melbourne, Australia
Joined Jul 2005
6,608 Posts
Mark, that's probably the easiest way since the supplied shunt has decent bolt connections that make it simple. A strand or two of heavy Cu wire should do the trick.

Still doesn't change my recommendation to others. Don't buy one of these.

JohnQUOTE=mrforsyth;23075632]John,

FWIW, I had a cheapy current shunt / meter that I got from eBay a good while ago that was also reading quite high. Like you, I could not adjust it within a range that was suitable for my needs. I then hatched an idea to add a parallel conductor to lower the voltage drop and 'adjust' the shunt to the point that it is now very usable in my application and reasonably agrees with both my homebrew shunts and my Medusa Power Analyzer.

Mark[/QUOTE]
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Old Oct 23, 2012, 12:37 AM
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So. Cal.
Joined Oct 2004
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Right there with you John. Makes me crazy when I buy something, expect it to work within a reasonable margin of accuracy, and am ultimately disappointed.

The upshot is that if I can fiddle with it to get it to work, it takes a little of the sting away. Still, I will also encourage others to steer clear of the offending product.

Mark
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Old Oct 23, 2012, 04:54 AM
ancora imparo
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Melbourne, Australia
Joined Jul 2005
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Just an update on this cheap 100Amp meter.

Adding a extra shunt across the supplied one with three strands of 0.7mm copper wire brought the calibration about mid position on the little pot and I was able to get it fairly accurate. It is hard to get the tiny pot adjusted better than a 0.2A increment. The supplied shunt is 0.75mOhm and my added wire is about 1mOhm.

It turned out to be reasonably accurate over a 7Amp to 75Amp range which is as high as I can go easily. Variation was only 0.2 - 0.7 Amp over the range against my Emeter. Up to 75A the extra shunt was not getting warm which makes sense as it has only about 30A through it and the total power is then less than 1 Watt. Even at 100A it isn't going to be more than 2 Watts and the thermal drift due to the Cu wire will be an issue but not a big one.

So if you are prepared to muck around with it AND have an accurate Wattmeter or Ammeter to calibrate it against it makes a usable current meter for these big supplies for $13. If the meter reads LOW instead of high like mine did, then it is simple enough to file a slot in the shunt supplied to raise the reading. You might even get one that works properly as it comes.

All in all hardly worth the effort IMO. Better to spend more and get the more versatile, decent DC10-90V 100A Dual LED Display Voltmeter Ammeter Voltage AMP Power Meter from the same supplier that can be simply and accurately calibrated on the display.


http://www.aliexpress.com/store/prod...591938056.html

John
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Old Oct 23, 2012, 08:41 AM
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So. Cal.
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Nicely done, sir!

Interesting that your added resistance was more than the shunt itself. Gotta love typical QC practice. Likely that the shunt and meter that you received were not necessarily made for one another and were simply pulled from a bin and tossed in a bag. Sad thing is that you're not alone here and others may not know the gross inaccuracy...

Mark
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Old Oct 23, 2012, 05:20 PM
ancora imparo
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Melbourne, Australia
Joined Jul 2005
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Mark, the shunt was in parallel as I had to lower the total resistance. I didn't expect it to be almost the same value as the original though. If it had been less than the existing resistance I would have been really surprised!

If my measurements are correct, the shunt supplied was as per specification (ie 75mV/100A) so I wonder about the "mismatch" theory.

I'm thinking these mV range digital panel meters are all the same - otherwise why produce different sized shunts for different currents. It would be cheaper to make a single shunt with an internal resistor in the meter that changes to give the correct FSD and with a pot intended only to calibrate them over a limited range.

Could be that the wrong components were put together but the label on the meter says it is the correct one. It's also possible someone assembled the meter with a wrong internal resistor. Who knows - the end result is crappy stuff regardless. Mr QC was out to lunch that day.

Anyway we are getting away from the topic.

Bottom Llne: Don't use one of these as a meter on your PS and expect it to be accurate without checking it against another known meter first.

John

Quote:
Originally Posted by mrforsyth View Post
Nicely done, sir!

Interesting that your added resistance was more than the shunt itself. Gotta love typical QC practice. Likely that the shunt and meter that you received were not necessarily made for one another and were simply pulled from a bin and tossed in a bag. Sad thing is that you're not alone here and others may not know the gross inaccuracy...

Mark
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Old Oct 23, 2012, 05:26 PM
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Germany, TH, Hildburghausen
Joined Jul 2012
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please help me ,i operated on my dps 1570 with 15 volt ,overcurrent-170 A???for less than 1 min. and suddenly it made a big bang and destroyed my dps-1570ab the fuseautomat triggered .

what do you think, are the only two transistors broken?
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////more power is needed //
how can I switch 2* dps 2000bb
so that load sharing, current sharing, load balancing works ?
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Old Oct 24, 2012, 03:42 PM
Steven
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United States, CT, East Hartford
Joined May 2010
504 Posts
You probably need to replace all 4 Mosfets.



It's best not to drive any PSU to maximum for long durations.

For the IBM DPS-2000BB just connect pins B1 together to utilize the current share funtion.

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Old Oct 24, 2012, 10:20 PM
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United States, AZ, Gilbert
Joined Jul 2010
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Quote:
Originally Posted by jocanon View Post
Want an on/off switch?

edit:
For all the PMs...these are not ready to sell yet...coming soon. I just got this first one made last night, what do you think? As soon as I get another part for my dummy load I am going to be able to fully test the power cords under full load (47 amps DC) to be sure they hold up to the current. I have no doubt they will as everything is overrated. The switch is rated at 15 amps AC, the two paralell plugs are 10 amps each, so that is 20 amps, and the 14 AWG main cord is rated at 15 amps. At max the PSUs run in series shouldn't pull more than 13 or so amps at 110 volts AC, I will be testing that too.
They are available now here:
http://www.rcgroups.com/forums/showt...8#post23093635
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Old Oct 25, 2012, 01:13 PM
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Joined Oct 2012
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Hi guys, I am looking for a 12v DC power supply, maybe 2000watts or more, but I need to work in 110v AC

Can some point me one???

Thanks a lot...
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Old Oct 25, 2012, 02:00 PM
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Joined Oct 2012
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I just find this one that work with 110v AC rated in 75amp, this one can work for me, now the thing is how to turn this on, can someone help me?

http://www.ebay.com/itm/HP-BLc3000-E...item27cc0509c4

Thanks again.
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Old Oct 25, 2012, 07:51 PM
Ham Operator, Central Texas
Joined Oct 2012
6 Posts
I am new to this site and have been impressed by the knowledge imparted by others, especially xandrios, regarding the server supplies.

I recently picked up a free Dell N870P-SO, 12V 75A supply and am trying to get ir up and running based on what I have learned by reading these messages.

Powered up the supply and got it to output 12.25V but the voltage drops with load. It is similar in connections to post #1840 but only 3 12V outputs and 3 grounds, plus the 4x6 set of pins. Based on that information, this is what I see on the pins when plugged in but not turned on:

A1, B1, C1, D1 and D2 - +12V stby

B2, B3, B4, B5, C3 and D4 - Ground (to case also)

A2, A3, A4, A5, A6, B6 and C6 - about 3.3V

C5, D5 and D6 - less than 0.5V

Grounding pin A6 turns on the variable speed fan but not the output.

Grounding pin C6 turns on the supply and D5 goes to 3.3V.

Loading the supply to about 5A causes voltage to drop from 12.25 to 12.0, have not tried more load yet.

Any comments would be appreciated.

Will post more info on the N870P as I discover it.
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Old Oct 25, 2012, 09:36 PM
Ham Operator, Central Texas
Joined Oct 2012
6 Posts
Further to #1844 -

Connecting 12K resistor from +12 to D5 increases output to 12.75V, using 4.7K does the same.

Readings earlier were due to bad connection, with 10+A load, drop is only 0.05V to 12.20V
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