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Old Aug 24, 2012, 10:45 AM
Stop scaring my donkey!
JohnathanSwift's Avatar
Greenland
Joined Mar 2012
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Dear Jo,

I have built two, 24 volt "units," and each has a small voltage fluctuation-I've never bothered to measure it, and I don't think it as extreme as yours; however, I bought some 24 volt, ready-made supplies since out of ignorance I feared the two units I built.
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Old Aug 24, 2012, 11:45 AM
Registered User
Puerto Rico, San Juan
Joined Feb 2012
38 Posts
Quote:
Originally Posted by Harry H View Post
There must be something simple you are overlooking. I know you have posted in the other thread but if you start by doing what rchelijc did in post #8 (photo) http://www.rcgroups.com/forums/showthread.php?t=1581061
and have removed the hot swap, cut and insulated the 2 wires that were connected to the hot swap, all is left is the ribbon cable. Are you sure you are viewing the cable numbering correctly starting with the red wire in the upper left corner and reading from right to left going down the cable? I grounded 1&2 directly to the ground post and jumped 4,5 &8 together (as you know, there are other ways). Check for continuity. Since you have 4 of these and you can't get it to work, there must be something you are overlooking. Good luck.

Harry
I have cut and insulated the 2 wires from the hot swap. If I understood the ribbon wiring right, I'm counting from left to right, red wire being #1 and so forth. Please correct me if I'm wrong.

Thanks.
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Old Aug 24, 2012, 12:08 PM
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Harry H's Avatar
Los Angeles
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It is from right to left. That might be your problem.

Harry
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Old Aug 24, 2012, 01:42 PM
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Puerto Rico, San Juan
Joined Feb 2012
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Quote:
Originally Posted by Harry H View Post
It is from right to left. That might be your problem.

Harry
I'm not using the pin header. I removed the pin header and twist/solder the wires together, as in the pic below. Please confirm if this does not seem correct.

Thanks.
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Old Aug 24, 2012, 05:29 PM
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Harry H's Avatar
Los Angeles
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It looks correct if you have the corresponding wire numbers that match the pinout from the diagram. I just didn't ground #3 for the fan speed as I have my supplies mounted in a tool box that mutes it somewhat. I personally don't think the fan speed should be lowered when mounted in a box unless you add more fans.

Harry
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Old Aug 26, 2012, 06:15 AM
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Joined May 2012
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prjoe - If I did not remember wrongly, I recall reading about someone else having fluctuations on his power supply when tested with a multimeter, but when connected to his powerlab it became stable.

Have you tried hooking them up separately as 12V units and see if they are stable as standalones?
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Old Aug 26, 2012, 12:42 PM
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If anyone is interested, here is how I did mine:









NOTE:
In order for the ribbon cable to be long enough so as to attach to JGND directly without any extension wires, the original header has to be pried off and the short length of wires that are already inside the header be re-used. If you simply snip off the entire header the ribbon cable will be a tad too short. Anyway, should that happen just solder on an 18 AWG extension wire.

ONLY FOR THE SIDE WITH DC GROUND REMOVAL:
The nylon flanged washer was mounted on the underside for both holes of the board, with the 'tubing' portion going through the board just nicely. This was followed by the normal nylon washer on top of the board and the nylon screw to hold everything together. I did not cut any jumpers or copper traces.

You would want to:
1. Test for (lack of) continuinity between the chassis and your DC common ground eg. your JGND negative rail if you have done it my way by connecting ribbons 1-5 to the JGND rail.
2. Test for (lack of) continuinity between the Earth pin on AC input socket and DC common ground.
3. Test for (presence of) continuinity between chassis and Earth pin on AC input socket.

This will ensure that DC ground has been safely removed from AC ground, but with AC ground still remaining intact throughout the chassis.
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Last edited by yhchoong; Aug 26, 2012 at 01:19 PM.
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Old Aug 27, 2012, 09:52 AM
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Puerto Rico, San Juan
Joined Feb 2012
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Quote:
Originally Posted by yhchoong View Post
prjoe - If I did not remember wrongly, I recall reading about someone else having fluctuations on his power supply when tested with a multimeter, but when connected to his powerlab it became stable.

Have you tried hooking them up separately as 12V units and see if they are stable as standalones?
yhchoong,
I've hooked them up separately as 12V and they are indeed stable. The fluctuation starts only when touched together.
I have done the wiring same as you did, except:
I'm using wires 1,2,3 shorted to GND, and 4,5,8 shorted together.
I also tried your setup, 1,2,3,4,5 shorted to GND, same results.
I used the same ring terminals, 10GA. silicon wire.
The alum. L-plate I attached from the outside with the screws from swap board.
For isolation I used #6 fiber washers. (Tested for no continuity ok)

I hooked the units to the PL8, and it does not detect the voltage fluctuation.
Might it be that the PL8 is not as sensitive as the voltmeter?
I have a loaned Dell dual server PS from a friend that is stable all the way through the charge.
I just would like to make sure this fluctuation will not damage my charger with continued use.
Where do you purchase those M3 plastic washers and screws?
great pics of you PS.

Thanks for your suggestions.
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Old Sep 25, 2012, 03:39 PM
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there is so much to read, but good info
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Old Nov 29, 2012, 02:54 PM
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Germany, NRW
Joined Feb 2001
536 Posts
Hey guys,

great information here, thanks all for sharing. :-)

I just came from testing my 24v PSU, and have a **HUGE and DANGEROUS** problem, hope you can help me.

One 12v HP PSU is "normal", so no disconnected AC ground or something. On the 2nd PSU I disconnected AC ground from the inside 3 pin connector inside the unit.

When I put them in series, I tried two scenarios:

1) The modified PSU with no AC ground provides the (+) for 24v, the other one provides the (-)
RESULT: I have 24v for 2 seconds, then the voltage drops to 12v again. Not good

2) The modified PSU with no AC ground provides the (-) for 24v, the other one provides the (+)
RESULT: I have a steady 24v on the output, however both AC power cables of the PSUs went crazy hot (! almost melted!) after only 10-20 sec. run. I instantly disconnected both units from power, smoke came up.

Does anyone of you experts have an idea what went wrong?!

Thanks a lot in advance,

Jens
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Old Nov 29, 2012, 07:39 PM
Use the 4S Luke
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USA, TX, Euless
Joined Aug 2003
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Yes. First reconnect the ground near the AC input.
Second, Read here about isolating (un-grounding) the output.
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Old Apr 01, 2013, 12:40 PM
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United States, CA, Richmond
Joined Dec 2007
165 Posts
Voltage Drop?

My 600PB has worked fine for a couple of years and then yesterday I hooked it up to the charger and tried to charge my 5S/5000mAh lipos and the fan speed dropped, and in short order the charger (TP820CD) showed a momentary "voltage" type error. The charger immediately went back to the "start charging" screen so I didn't get an accurate read on the error displayed.

Any ideas?

Thanks in advance for your help.

Bill
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Old Apr 03, 2013, 08:20 PM
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Joined Sep 2005
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I am getting ready to convert my two DPS-600PB into a single 24V power supply and like this one the most because it looks like a cleaner package.

The question I have since both power supplies are AC grounded so you can bolt them together, my only concern is, what if you accidentally ground the floating -DC of the floating PS to the chassis when the charger touches it? Or touch the floating negative post and the case with your hands, any danger here?
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Last edited by SuperFatCat; Apr 03, 2013 at 08:34 PM.
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Old Apr 04, 2013, 07:15 AM
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Cleveland Cuyahoga, Ohio, United States
Joined Dec 2000
401 Posts
As a further safety measure I isolate the two chassis with a piece of Plexiglas.
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Old Apr 04, 2013, 11:07 AM
Use the 4S Luke
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USA, TX, Euless
Joined Aug 2003
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Jim - If both chassis are still grounded via the power cord, there is no need to separate them.

SuperFat - Since the negative side of the floated power supply is at 12V above ground, making any connection from it to ground will result in the power supply with the grounded negative output seeing a short circuit and shutting down. It may damage whatever caused the short before it shuts down.
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