Determing DC power input polarity

[Cursitor Doom]

Hi all,

I bought a ton of surplus electronic gear (almost literally) and among
some of the cases of odd bits and whatnot I came across an AOR AR3000
"communications receiver" (I use quotes as it's nothing like any *proper*
CR I've ever encountered, but I guess that's my age prejudice). Anyway,
it has 3 pins on the back panel marked "12V DC in" but no polarity
indication. I'm guessing one of those pins is just for alignment to
ensure the plug goes in the right way around and the other two are pos
and neg. I can find no power lead for this radio. Is it possible to
determine which pins are which from carrying out some basic resistance
measurements between them? I really don't want to hook it up the wrong
way around.
BTW, the service manual I have downloaded off the net does not help at
all in this respect.

TIA.

 

[Cursitor Doom]

On Sun, 10 May 2015 11:06:51 -0400, Pat wrote:

On Sun, 10 May 2015 12:18:21 +0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

Hi all,

I bought a ton of surplus electronic gear (almost literally) and among
some of the cases of odd bits and whatnot I came across an AOR AR3000
"communications receiver" (I use quotes as it's nothing like any
*proper*
CR I've ever encountered, but I guess that's my age prejudice). Anyway,
it has 3 pins on the back panel marked "12V DC in" but no polarity
indication. I'm guessing one of those pins is just for alignment to
ensure the plug goes in the right way around and the other two are pos
and neg. I can find no power lead for this radio. Is it possible to
determine which pins are which from carrying out some basic resistance
measurements between them? I really don't want to hook it up the wrong
way around.
BTW, the service manual I have downloaded off the net does not help at
all in this respect.

TIA.

Google "AOR AR3000 power connector" and look at the images. There is
one where someone adapted two individual wires to that socket. Red is
on the right and Black on the left (as seen from the back)..

Separately, someone mentioned that older Hayes modems used that same
connector. I don't remember that but it's possible. Maybe your tons of
surplus includes some of those.

Pat

There may well be the plug for it somewhere among the vast amount of
STUFF I took delivery of. However, I tried out Michael's suggestion of
taking it apart and there was a large electrolytic across the pins in
question internally, helpfully marked, just as he said.
So - for the benefit of anyone in future trying to look this info up -
looking at the socket from the rear, the neg pin/gnd is on the left; the
right is +12V and the top pin is n/c.

 

[N_Cook]

On 10/05/2015 13:18, Cursitor Doom wrote:

Hi all,

I bought a ton of surplus electronic gear (almost literally) and among
some of the cases of odd bits and whatnot I came across an AOR AR3000
"communications receiver" (I use quotes as it's nothing like any *proper*
CR I've ever encountered, but I guess that's my age prejudice). Anyway,
it has 3 pins on the back panel marked "12V DC in" but no polarity
indication. I'm guessing one of those pins is just for alignment to
ensure the plug goes in the right way around and the other two are pos
and neg. I can find no power lead for this radio. Is it possible to
determine which pins are which from carrying out some basic resistance
measurements between them? I really don't want to hook it up the wrong
way around.
BTW, the service manual I have downloaded off the net does not help at
all in this respect.

TIA.

Does the sm tell you what kind of polarity prot. there is, or not?
Wrong way and zilch or wrong way and more than .6V blows a fuse etc.

 

[Michael Black]

On Sun, 10 May 2015, N_Cook wrote:

On 10/05/2015 13:18, Cursitor Doom wrote:
Hi all,

I bought a ton of surplus electronic gear (almost literally) and among
some of the cases of odd bits and whatnot I came across an AOR AR3000
"communications receiver" (I use quotes as it's nothing like any *proper*
CR I've ever encountered, but I guess that's my age prejudice). Anyway,
it has 3 pins on the back panel marked "12V DC in" but no polarity
indication. I'm guessing one of those pins is just for alignment to
ensure the plug goes in the right way around and the other two are pos
and neg. I can find no power lead for this radio. Is it possible to
determine which pins are which from carrying out some basic resistance
measurements between them? I really don't want to hook it up the wrong
way around.
BTW, the service manual I have downloaded off the net does not help at
all in this respect.

TIA.


Does the sm tell you what kind of polarity prot. there is, or not?
Wrong way and zilch or wrong way and more than .6V blows a fuse etc.

But if there is a diode across the DC line, that would show the polarity.

Other than that, or finding details online, one could open it up and see
which pin goes to ground. At this point, negative ground is the norm.
Find where the other pin goes, presumably to an electrolytic, and its
polarity markings will provide secondary information.

Michael

 

[Pat]

On Sun, 10 May 2015 12:18:21 +0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

Hi all,

I bought a ton of surplus electronic gear (almost literally) and among
some of the cases of odd bits and whatnot I came across an AOR AR3000
"communications receiver" (I use quotes as it's nothing like any *proper*
CR I've ever encountered, but I guess that's my age prejudice). Anyway,
it has 3 pins on the back panel marked "12V DC in" but no polarity
indication. I'm guessing one of those pins is just for alignment to
ensure the plug goes in the right way around and the other two are pos
and neg. I can find no power lead for this radio. Is it possible to
determine which pins are which from carrying out some basic resistance
measurements between them? I really don't want to hook it up the wrong
way around.
BTW, the service manual I have downloaded off the net does not help at
all in this respect.

TIA.

Google "AOR AR3000 power connector" and look at the images. There is
one where someone adapted two individual wires to that socket. Red is
on the right and Black on the left (as seen from the back)..

Separately, someone mentioned that older Hayes modems used that same
connector. I don't remember that but it's possible. Maybe your tons
of surplus includes some of those.

Pat