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Sep 25, 2012, 03:24 PM
Registered User
bump thanks for the info
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Sep 28, 2012, 06:55 AM
Registered User
Thanx everyone for all the info here. It was a big help determining how to mod these supplies. In the end all that is required is a bit of solder bridging out five terminals and a short chunk of 30 gauge to ground - sweet.
Sep 28, 2012, 03:32 PM
Steven
xandrios's Avatar
The DPS-600PB zeke mod. I like it.
Oct 02, 2012, 09:03 AM
jocanon's Avatar
OK, so I got the temperature control circuit working...almost, I still need to do the final tweaking and waiting on parts from Mouser...but I am pretty stoked about it. I have to give credit where credit is due to ronv at electro-tech-online for designing the circuit, I had the idea, but he made it work with just one op-amp, 4 resistors and a thermistor. We decided to simply use the PSUs built in fan control pin, pin #4 and control the speed of the fan based on temperature by changing the voltage on this pin. 4.6v to Vcc (Vcc=about 12v) is the range on pin 4 that will adjust the fan speed. The fan reaches a minimum speed at 4.6v and even if the voltage from the op-amp output drops below 4.6v (i.e. when the PSU first starts and it's cold) the fan will still not go below the minimum speed. We decided not to let the fan stall. The circuit ronv designed is excellent in my opinion because it doesn't generate any heat (the original design with a MOSFET would have wasted a lot of energy in the form of heat and required heat sinking the FET to the case with non-conductive thermal epoxy) and it doesn’t require any mods to the PSU's internal fan wiring...no 555 timer and no splicing of the fan wires! So the built in protection is still intact where the PSU will shut down if the fan dies, meaning if it stops getting a tach reading from the fan, the PSU will still shut down to protect itself. My original design had to trick the PSU into thinking it had a tach pulse with a 555 timer because we disconnected the fan and allowed it to stall, but we dumped that idea. Thanks ronv! Once I get all the parts and get the circuit dialed in, I will post some pictures/youtube video showing it in action with the 1500+ watt water cooled (thanks to ()blivion!) dummy load we made as well.

If anyone is interested, you can find the schematic for the temperature controlled circuit, dummy load and all information about how we made the circuits in this thread:

http://www.electro-tech-online.com/e...ircuit-62.html
Last edited by jocanon; Oct 02, 2012 at 10:19 AM.
Oct 02, 2012, 09:14 AM
Suspended Account
Yes, but when can those of us with no skill buy a "kit?"

Keep up the great work!
Oct 02, 2012, 09:28 AM
jocanon's Avatar
In due time my friend
Oct 02, 2012, 09:39 AM
Suspended Account
Money waiting: two systems to refit, each with ribbon cable modifications-let "us" know!
Oct 02, 2012, 09:40 AM
jocanon's Avatar
Thats good that you are using the ribbon cable, because the mod will be easiest to do that way. It's an easy mod with either the pin method or the ribbon cable method but just a little easier with the ribbon cable.
Last edited by jocanon; Oct 02, 2012 at 09:51 AM.
Oct 02, 2012, 10:07 AM
Suspended Account
Money waiting!
Oct 02, 2012, 12:16 PM
Registered User
Oct 03, 2012, 08:13 AM
Registered User
Quote:
Originally Posted by jocanon
OK, Once I get all the parts and get the circuit dialed in, I will post some pictures/youtube video showing it in action with the 1500+ watt water cooled (thanks to ()blivion!) dummy load we made as well.
Does this mean you have successfully pulled 1500 watts steady from these units? (i assume a 24v set-up)
Oct 03, 2012, 12:47 PM
Registered User
Just finished 6 days of charging at eWeek. One 25V on a super duo and one 12.5V on 250 watt 720i. Both have only the "pin 4" mod hard wired. (no switch)

Stayed on all day every day charging mostly 5 and 6 cell 5000mah packs at near capacity a lot of the time.

Highest ambient temp was 88 degrees... never skipped a beat.
Oct 03, 2012, 03:07 PM
jocanon's Avatar
Quote:
Originally Posted by SCOREMAN
Does this mean you have successfully pulled 1500 watts steady from these units? (i assume a 24v set-up)
No, the dummy load is capable of more than I can get from the PSUs. I did push them to the limit just to see what would happen. At about 55 amps the over current protection kicked in, the PSU just shut down, and my house lights got a little bit brighter . Once I shut power off to the PSU and then powered it back up, the PSU worked like normal without a hiccup. So at 55 amps X 24 volts the most you can get would be about 1,320 watts, but this is not reccomended. I wouldn't go above the rated current of 47amps.
Oct 03, 2012, 07:29 PM
jocanon's Avatar
Nevermind
Last edited by jocanon; Oct 10, 2012 at 12:48 AM.
Oct 10, 2012, 04:08 PM
jocanon's Avatar
For anyone that's interested, here is a link to a video of the dummy load I made to test these PSUs..

Dummy Load (13 min 31 sec)


I have been blowing TVS's on my dummy load, my latest theory is that it's a faulty PSU. I am going to go home tonight and test out that theory by using a different PSU on my dummy load (I have always been using the same PSU everytime the TVS blew). One thing that makes me think it is a faulty PSU is that the isolated PSU's volatage gets unstable as current increases above about 30 or 40 amps. Has anyone else experienced this?

Update:
Tried it with a different isolate DPS-600PB. The voltage is 25v at no current and only drops .2 volts to 24.8 at 47amps but it is a solid 24.8 amps, not fluctuating around like the other one, so I think the problem was a faulty PSU after all, it was spiking up to 170v!, according to one $5 volt meter, but according to another $5 volt meter it was bouncing all around but mostly staying below 21v (which one to believe, hmm probably the high one since it was blowing the TVS diode). This is a good reason that shows why I built this dummy load in the first place, so I can test each PSU to make sure it's not faulty.
Last edited by jocanon; Oct 10, 2012 at 06:24 PM.


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