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Old Aug 24, 2012, 05:54 AM
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Near Kingston, Ontario, Canada
Joined Dec 2004
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Quote:
Originally Posted by prjoe View Post
The voltage stays solid when the units are just 1mm apart. So it might be the inductive coupling you're talking about. The question is, can this be avoided, worked around? How is it no one else has experienced this before using the same wiring scheme I'm trying to use? I wish I knew something about electrical circuits. I don't like to give up on things, but I'm getting nowhere with this. I'm left with 4 nice HP 600PB paperweights. I must be missing on some small detail.
Thanks for the reply.
It sure looks like you are having inductive coupling between the two power supplies.Try a piece of sheet metal between the supplies to act as a shield. Have you measured the voltage with a substantial load on the supplies or does this only occur when unloaded?

Dave
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Old Aug 24, 2012, 07:52 AM
Steven
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United States, CT, East Hartford
Joined May 2010
504 Posts
A simple piece a paper between the PSUs will help determine if the problem is caused by inductive coupling or by the physical contact.

If you still have the problem with the sheet of paper in between and PSUs pressed together, then most likely inductive coupling is the problem.

If you don't have the problem then most likely the physical contact is causing the problem.

This may mean they become capacitively coupled somehow when touched together. The problem would be internal.

A capacitively coupled circuit will show no continuity and no DC on a multimeter.

If this is the case then AC ripple or any type of AC on the DC line may be the culprit .

A scope would come in handy.

Fully isolate DC ground on both PSUs when running in series. This means also having to cut the main board ground jumpers in conjunction with what you have already done.

http://www.rcgroups.com/forums/showp...41&postcount=8

The voltage variation should decrease or disappear.
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Old Aug 24, 2012, 11:34 AM
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Puerto Rico, San Juan
Joined Feb 2012
26 Posts
Quote:
Originally Posted by xandrios View Post
A simple piece a paper between the PSUs will help determine if the problem is caused by inductive coupling or by the physical contact.

If you still have the problem with the sheet of paper in between and PSUs pressed together, then most likely inductive coupling is the problem.

If you don't have the problem with the sheet of paper in between and PSUs pressed together, then most likely the physical contact is causing the problem.

This may mean they become capacitively coupled somehow when touched together. The problem would be internal.

A capacitively coupled circuit will show no continuity and no DC on a multimeter.

If this is the case then AC ripple or any type of AC on the DC line may be the culprit .

A scope would come in handy.

Fully isolate DC ground on both PSUs when running in series. This means also having to cut the main board ground jumpers in conjunction with what you have already done.

http://www.rcgroups.com/forums/showp...41&postcount=8

The voltage variation should decrease or disappear.
I will try your suggestions tonight after work. Do you think the paper between the cases will help to find out, because the units will still be in contact through the front aluminum L-plate. The units are tied together by a single L-plate with the mounting screws from the daughter board. Is it safe to isolate both PSU's and let them touch? Pardon my ignorance.

Your suggestions are appreciated.
Thanks.
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Old Aug 24, 2012, 12:07 PM
Steven
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United States, CT, East Hartford
Joined May 2010
504 Posts
The L-plate will need to be removed before testing if you are curious as to the root of the problem.

Otherwise, just isolate DC ground on both PSUs and cut the main board ground jumpers.

Let's hope for the best.
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Old Aug 27, 2012, 11:26 AM
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United States, FL, Lake Worth
Joined Jun 2012
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Got it all together and tested yesterday.

Thanks everyone for this awesome guide!
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Old Aug 27, 2012, 12:09 PM
Stop scaring my donkey!
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Greenland
Joined Mar 2012
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Nice work-did you modify the fan controls?
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Old Aug 27, 2012, 12:38 PM
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United States, FL, Lake Worth
Joined Jun 2012
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I put ribbon 1-5 to ground, so fans are nice and quiet :-)

Next I want to put all of it neatly into a Kobalt toolbox
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Old Aug 27, 2012, 01:12 PM
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Joined Aug 2012
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Hi all,

firstly great thread thanks followed it to build a 24V series PSU.

but i have run into a problem.

i isolated the DC ground on one unit, double checked it and it is isolated. i them connected the two PSU in series got 24V for a bout 2 minutes then the PSU 1 one which is standard (no DC ground removed) shutdown now it wont turn back on.

when i power off and ON, it briefly turns on but the fan wont come on, green led comes ON output for one seconds and then shuts down. then no output green led also goes out. every power on and off i can hear a click when it switched on then another click when it switched off. it looks like i have tripped something inside. is there way to reset these power supplies?

some things to note is.

both PSU's worked fine before when they were not connected in series for about 3 hours after i got them.

is it necessary that the two PSU's body touch together since they are not currently even though i have isolated DC ground on one. i didn't touch the PSU together yet as i was only in the phase of testing yet.

can this PSU be reset or have i just got a duff one .

any help would be greatly apprecated.

thanks
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Old Aug 27, 2012, 03:12 PM
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Puerto Rico, San Juan
Joined Feb 2012
26 Posts
Quote:
Originally Posted by xandrios View Post
A simple piece a paper between the PSUs will help determine if the problem is caused by inductive coupling or by the physical contact.

If you still have the problem with the sheet of paper in between and PSUs pressed together, then most likely inductive coupling is the problem.

If you don't have the problem then most likely the physical contact is causing the problem.

This may mean they become capacitively coupled somehow when touched together. The problem would be internal.

A capacitively coupled circuit will show no continuity and no DC on a multimeter.

If this is the case then AC ripple or any type of AC on the DC line may be the culprit .

A scope would come in handy.

Fully isolate DC ground on both PSUs when running in series. This means also having to cut the main board ground jumpers in conjunction with what you have already done.

http://www.rcgroups.com/forums/showp...41&postcount=8

The voltage variation should decrease or disappear.
I followed your instructions and getting the same results.
I isolated both units (No-continuity test ok)
Tested each individually without L-plate (12.6V each side steady)
As soon as they touch, bam, voltage dance.
Put a sheet of paper between the units and the variation still there, but at a lesser range.
I hooked my PL8 and the charger reads the voltage as 25.1V steady, but the voltmeter readings varies a lot.
(I've tested a Dual Dell PS setup and it's steady at 24.3V with the same voltmeter from the same wall outlet)
Could it be that the charger is not as sensitive as the voltmeter?
My fear is that these voltage variations could damage the PL8.

I think I might close these up and isolate physically on the outside, even with the fluctuation.
Or better yet, take them to my job's crusher machine and relieve the stress these have caused me while watching as they come out paper thin.

It is frustrating seeing everyone here making these PS with no troubles at all, and I can't seem to get it right.
Or is it that people don't test the final product with a voltmeter before closing it all up?
I wonder if I had done it with the pins in the front, never used the ribbon, the story would be any different. Too late for that, the hot swap boards are gone.

Thanks to all who have tried to help.
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Old Aug 27, 2012, 03:33 PM
Stop scaring my donkey!
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Greenland
Joined Mar 2012
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Mine have a small fluctuation, never measured; however, out of other fears I replaced them with a Junsi 1200.

My PL 8's never even burped, but I only had about a month or two of PSU before buying the Junsi.
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Old Aug 27, 2012, 03:39 PM
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United States, FL, Lake Worth
Joined Jun 2012
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Mine fluctuate a little bit, ultimately I plan on getting the Junsi or Meanwell
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Old Aug 28, 2012, 01:26 AM
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Salem, Oregon
Joined Dec 2008
125 Posts
Quote:
Originally Posted by prjoe View Post
Or is it that people don't test the final product with a voltmeter before closing it all up?
Mine are rock solid, zero voltage fluctuation, but that's with the cases fully assembled with all screws tight. I also didn't remove the output board. If you haven't tried them fully assembled it's worth a shot. If there's any coupling, closing up the cases should eliminate it (or at least drastically reduce it).

The fluctuations you're seeing may also just be noise on the output lines. (This is where a scope would be handy.)
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Last edited by Dusey52; Aug 28, 2012 at 01:42 AM.
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Old Sep 04, 2012, 03:58 PM
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Quote:
Originally Posted by JohnathanSwift View Post
Search for Akchu's thread and follow it!
I have searched for Akchu and it does not even show up as a member on here. Can someone please post his link

thanks
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Old Sep 04, 2012, 04:11 PM
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found it it was not spelled right in the original post.

http://www.rcgroups.com/forums/showthread.php?t=1369612
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Old Sep 19, 2012, 09:29 AM
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Indianapolis, IN
Joined Jan 2011
212 Posts
Question about the DPS-600:

i saw there were 2 ways to connect the three pins that turn on the PS. one is pins 6-8-10 and the other is pins 6-9-10. i tried it both ways and they both work. when i have 6-8-10 connected i have an output of 12.50V but when i have pins 6-9-10 connected i have an output of 12.66V. is there any problem using the 6-9-10 connection over the 6-8-10? i heard if you have the 6-9-10 connected it causes fluctuations in voltage when connected to another PS in series.
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