help - wiring Dell DA-1 with Pico 120W

[jv_guano]

Hi!

Finally I've bought a 120W Dell DA-1 adapter..

my "problem" now is how to wire correctly the Dell to the Pico..

i know the Dell has a six-pin socket, three of these are +12V and the other three are -.

if they are separated, is it safe to pack'em all together to the pico jack?

isn't it out there a guide about that?
I think I saw this guide an year ago on this forum, but couldn't suceed in finding it back again..

[MikeC]

Most likely, if there are 3+ and 3-, then all three pairs are in parallel. Easy enough to find out with a multimeter. If in parallel, then any two of the 3 "+" lines will result in zero resistance. Ditto the "-" lines.

[jv_guano]

many thanks for your kind reply!

so, if they are in parallel, can I wire the 3 + and the 3 - together to e female jack that will match the pico jack?

[MikeC]

yes, afaik -- but i'd want to check my guess with a multimeter first.

[jv_guano]

but...(may be I'm too tired, just got back home with flu, and I found my Dell Da-1 on my desk!!)

which pins should I test with a multimeter?
I mean, of course all..
but do I risk a short circuit if, let say, I test a + rail witha another + rail?

of course I do!!!

so, how can I guess which are the 3 negative pins and which the + ones?

many thanks!

(in the meantime, I'll look for a datasheet...)

I only found viewtopic.php?p=426395&sid=b260c1707000 ... 544#426395 this entry googling, but no answer..

I'll search deeper tomorrow, with a fresher mind!

[MikeC]

measure impedance across the outputs with the unit not plugged in or powered up. If in parallel, then any two of the 3 "+" lines will result in zero resistance -- Ditto the "-" lines.

[jv_guano]

yeah, your hint was very wise, yesterday I was really too tired to think about it!

so, I attach here the pic of the connector..



the two little dots above have an impedance going to 0.
the two square holes at each side have an impedance going to 0...

here's a little diagram..



it isn't exactly what I could imagine..

also, there's an imepdance going to 0 between the external metal shield and the two square pins on the right side here in the diagram (which, I could guess, are the two -)

so, maybe

the two right square pins are 12-
the two left square pins are 12+

and the two little dots in the upper side?????

[MikeC]

There are no other zero impedance results between any other pair of terminals?

If that's true, then there are 3 discrete lines.

The little round pins on top could be a discrete ground.?? If the AC plug has 3 pins, then the ground pin might/should be connected to these. Try your impedance test again between the AC plug and the output plug.

You should try plugging the unit into AC and use the volt meter across the terminals now. Set it for 20vdc range and see what you get across the various terminals. There is no risk of shorts. Test a + rail with another + rail and you'll get 0 voltage.

The thing is, you'll have to check the bare wires again after you cut the connector off, which you will have to do to use it with the picoPSU. So if it was me, I'd just cut the connector off, strip a half cm of insulation off the ends , and deal with the bare wires directly -- although now if you touch a + wire with a - wires, there IS a risk of short (and potential damage). But take care of how you handle the wires when the thing is plugged in, and you should be safe.

[jv_guano]

i must admit,you're really reading my mind (and really kind too!)
Yes,i'll have to cut all the wires when i'll be soldering a suitable jack for pico psu,but as u said,i want to avoid any possible risk of short circuit..

I double checked the impedance and it is exactly like i told u..just 2 couples of pins nearly equal to 0,the round pins leading to nxwhere instead..

What do you exactly mean with "3 discrete lines"? Like The situation we guessed at the earliest stage?

I checked with the AC plug and i found an imped nearly equal to 0 between the ground AC and the two square pins on the left side..

That's really thrilling my poor electrics knowledges..
Btw,why do you say i do not risk using the voltmeter with the AC plugged?
I had a bad experience with the voltmeter some months ago ,don't want a replay at all!!

Really thanks for ur huge help so far!

[MikeC]

What do you exactly mean with "3 discrete lines"? Like The situation we guessed at the earliest stage?

3 separate lines.... +12V, -12V and ground. But your other finding changes this.

I checked with the AC plug and i found an imped nearly equal to 0 between the ground AC and the two square pins on the left side..

That suggests those are ground as well as -12V. Maybe the little round pins have no voltage at all? Maybe they are only connected to each other?

Btw,why do you say i do not risk using the voltmeter with the AC plugged?

There's no risk if you are measuring voltage. The multimeter only allows a trickle of current through it so the voltage can be measured -- very high resistance, so no virtually no current, therefore no power and no risk. If you try to measure resistance while the unit is plugged into AC, then you'll have a problem.

[gammelgam]

I've done exactly this.

viewtopic.php?p=431626#431626

There is a picture on the rear label of the Dell brick. I soldered the two +12 wires together, and the two Common (ground) wires together *with* the pin labelled "remote". The pin "Future use" was simply isolated using tape.

The label can be seen at: http://www.mp3car.com/vbulletin/715115-post4.html

The "Remote" pin is used to turn on the Power Brick (look at the led). When this is connected to ground it will always be on (led lit). To enable on/off, solder it to the ground wires through a button/switch.

[jv_guano]

oh, I was just plugging the AC wire according to last MikeC reply, when I thought, "let see if something new on the forum..."

thanks for your contribution gammelgam!

now that u told me, I see there's a spec under the PSU..but mine is covered with a stick, so I did not noticed before!!

just for the knowledges sake, the pin "future" what is meant to be used for?

many thanks again for your precious contribution!
and thanks again to this patient MikeC!

===

PERFECT!!

I connected together the pin with three paper clips (according to safety regulations in order to avoid short circuits! ) and the tester gave me back a wonderful 11.99/12.00 V!!

really excellent!

thank you guys, now I just need a jack and to improve my soldering skills!!

[gammelgam]

The "future use" pin is used for.....


.....future use....maybe?



Seriously: No idea.

[jv_guano]

The "future use" pin is used for.....


.....future use....maybe?



Seriously: No idea.

ok, it's like what I thought! tomorrow never knows...

btw, do you suceed in opening the PSU case?
well, it's not for a 24h/24 pc, but putting it in a metal cage with a fan would leave me more happy..

it has those hatred stars-like screws with a dot in the middle! never seen this variant..

[jv_guano]

sorry to bother you again...

the copper shield wrapped along the six wires...am I supposed to connect it to 12- ?

many thanks in advance!

I'd like to solder the Dell to the DC plug this afternoon...the pico too is ready, so really couldn't look forward to pump it up my system!

thanks!

[jv_guano]

hey!

I don't know where to throw my poor head...

all this work...and it is not working anymore!!!

I don't know what I'm missing...

I soldered together brown and red wire (+12V) and green wire (remote) to WIRE A
i soldered together white and black wire (-12V) to WIRE B
these two wires were connected to a DC jack.

the - on the DC jack has 0 impedance with the ground on the AC plug
the + on the DC jack has impedance with everything pin on the AC plug and with the - on the DC plug too

so everything is fine on the paper!
but when i connected it, the green light didn't turn on and no voltage is measured in the DC jack..

why that? i know, you have not an answer..
but on the Dell laptop socket everything was fine, but now, taking out the wires and putting them in a DC socket, seems not to have the same result..

I'm desperate...

I soldered the two +12 wires together, and the two Common (ground) wires together *with* the pin labelled "remote". The pin "Future use" was simply isolated using tape.

stupid me, I put the remote besides the two 12+ rails

now I rewired everything correctly and it's working!
I attached the pico too and the voltages are good too!!

[lesticx]

Bump!

Is it still working?

More importantly: how good are the voltages, and what about efficiency, if you can measure it?
I'm just trying to decide which way to go in powering my rig..