Great, I have a 1k pot. Just to be clear, what do you mean by ground pin? Is this one of the 24 jumper pins? Or is it one of the 6 main posts (left three are ground). Judging by the pin out diagram, I assume you mean PB1 as I don't see a ground pin. Or can I just go into any of the pins makred Logic Return? sorry, for the noob questions.

Also, I thought the resistors were required for a voltage drop. Is that not the case?

This is the full pinout for your PSU. Any pin that says logic return is ground. A3,B1,B3 etc.
Using the 1k resistor allows you to use the full pot rotation for adjustment if you use a 1k pot.
Just using the 1k pot alone will not allow us to use the full pot rotation for adjustment. But it will still work.
The pot itself will provide the voltage drop.

Okay so if I did use the resistor to get full range, it would be A2 to 1k resistor and then to the outer leg of the pot. Wiper to B2. Other outer leg to ground pin. Right?

Almost. If we use the 1k pot alone, we are creating a voltage divider at the center wiper.

If we use the 1k pot in conjunction with the 1k resistor, then we use the pot purely as a variable 1k resistor.

So you can leave one outer leg untied, or short one of the outer legs to the center wiper. Then just replace R2 with the pot.

So pin A2 to 1k resistor. Other end of 1k resistor to both pin B2 and to pot center wiper. Then one pot leg to ground.

Depending on how you have the pot connected, the fan speed may increase with a clockwise or counterclockwise movement of the pot.

Just swap to the other unused outer pot leg and ground it to reverse directions.

That makes sense. Based on the original drawing I thought we might only be using two legs and making a variable resistor. I'm going to give it a shot tonight. This stuff is pretty dang cool. Thanks for your help Xandrios

Questions make this stuff extremely dang cool !! Thank you.

Holy Schnickey it worked. At first I hooked it up and didn't see any change, but I was only running 2.4 amps through there. I jacked it up to 4.4 amps and turned the pot and the fan sped up a bit. I've got a new charger coming, so I'm sure I'll really see the difference then. Only question is how to tie all this up nicely. I've got it all working with alligator clips on my work bench right now. Soldering it in permanently is whole other story.

I used my PE6850 for the first time in anger over the weekend
http://www.rcgroups.com/forums/showp...postcount=1238

I charged 2 x 6s 5000mAH @ 6.5 amps and 3 x 3s 2200mAH @ 3.0 amps all at the same time.

The peak temperature was a respectable 49c (120F) - monitored at the air flow from the vent at the back.

I intend to order two more 5000mAH 6s batteries along with two more chargers so I'll have to increase the 3 output wire to 6 to take the full current that will be required.

All in all this was a very cheap way of providing all my 12v needs. Thanks for all you help.

Kev

hi,

do you know which pins control fan speed? i'd like to slow it down.

thanks!

Originally Posted by xandrios

Hey 376782,

The Dell 7000245(Poweredge 6650) PS is an oddball PS where you have to ground bias the voltage control pin.
This may also be why the manufacturer selected to keep the DC ground floating on this model.

Pin A1 controls voltage. Connect to ground via pot or resistor. Use only up to 13v max.
1.3k ohm ≈ 13v. Any higher than 13v will cause the PS to shut down even with a slight current draw. This is common with most PS as you near OVP.
Tested at 13v for 72A.
Pin D1 is the current share pin.

Guys, how do you cover up the 12v and ground solder points so someone doesn't accidentally touch them. I think I've seen some goo product you can put over it. What is that?

Touching them is not a problem. The voltage is only 12V and not dangerous.

Shorting them (ie bridging the positive and ground) would be an issue but the supply will shut down automatically.

Your call - but I wouldn't be concerned on safety grounds. I made a small cover from a plastic box that happened to be the right size and glued it on just 'cos it looked neater.

Anything that is an insulator can be used - liquid tape, silicone sealant, I would think even hot glue would be fine.

Be aware that if you ever have to repair the connection, tenacious gunk all over it makes it harder.

John

Originally Posted by chriscap

Guys, how do you cover up the 12v and ground solder points so someone doesn't accidentally touch them. I think I've seen some goo product you can put over it. What is that?

Hey ndamico.

You want to slow down the fans on the PE 6650 PSU even futher?

They already purr.

I wouldn't try to slow them down any futher.

Originally Posted by jj604

Touching them is not a problem. The voltage is only 12V and not dangerous.

Shorting them (ie bridging the positive and ground) would be an issue but the supply will shut down automatically.

Your call - but I wouldn't be concerned on safety grounds. I made a small cover from a plastic box that happened to be the right size and glued it on just 'cos it looked neater.

Anything that is an insulator can be used - liquid tape, silicone sealant, I would think even hot glue would be fine.

Be aware that if you ever have to repair the connection, tenacious gunk all over it makes it harder.

John

Yeah, I guess your right. I just want to cover it to keep someone from accidentally shorting it.

And if you use silicone sealant it needs to be the "non-acid cure" type.

I forgot to mention that.

Originally Posted by chriscap

Yeah, I guess your right. I just want to cover it to keep someone from accidentally shorting it.

hi all,

for dsp 450 cb1

is possible reduce speed off the fan ????

reduce 1/2 or 50 pour cent ???

bests regards

laurent on2vhf