I pulled an old Astron power supply out of mothballs today. It's a
13.8 volt / 20 amp supply (the RS-20A). I find that there's a
noticeable hum when I plug it in, and I also notice that a small
output voltage of one volt or so is measureable on it even when it's
turned off and unplugged.

What should this tell me about the condition of this supply? As it is
I'm nervous about using it.

Thanks,

Steve

what does the voltage read when it is turned on? an rs-20a is probably not
so old that caps would go bad, and the low voltage left over when you turn
it off probably means the caps are holding a charge.

"Steve" wrote in message
ups.com...
I pulled an old Astron power supply out of mothballs today. It's a
13.8 volt / 20 amp supply (the RS-20A). I find that there's a
noticeable hum when I plug it in, and I also notice that a small
output voltage of one volt or so is measureable on it even when it's
turned off and unplugged.

What should this tell me about the condition of this supply? As it is
I'm nervous about using it.

Thanks,

Steve

On Nov 4, 6:23 am, "Dave" wrote:
what does the voltage read when it is turned on? an rs-20a is probably not
so old that caps would go bad, and the low voltage left over when you turn
it off probably means the caps are holding a charge.

"Steve" wrote in message

ups.com...



I pulled an old Astron power supply out of mothballs today. It's a
13.8 volt / 20 amp supply (the RS-20A). I find that there's a
noticeable hum when I plug it in, and I also notice that a small
output voltage of one volt or so is measureable on it even when it's
turned off and unplugged.

What should this tell me about the condition of this supply? As it is
I'm nervous about using it.

Thanks,

Steve- Hide quoted text -

- Show quoted text -

When it's turned on the voltage reads 13.92.

Steve

Steve wrote:
When it's turned on the voltage reads 13.92.
============================
If you subsequently switch-off the unit does the output voltage rapidly
decline or is the change very slow (assuming you do not have any
external load)


Frank GM0CSZ / KN6WH

On Nov 4, 7:28 am, Highland Ham
wrote:
Steve wrote:

When it's turned on the voltage reads 13.92.
============================
If you subsequently switch-off the unit does the output voltage rapidly
decline or is the change very slow (assuming you do not have any
external load)

Frank GM0CSZ / KN6WH

The output voltage drops slowly when the unit is switched off. In
fact, I compared the voltage drop on the RS-20A to the voltage drop on
an RS-12A that I currently have in use. The voltage drop on the RS-20A
is much slower than on the RS-12A, and when the voltage has dropped
down to around 4 or 5 volts then it really slows to a snail's pace.

Steve

On Nov 4, 9:13 am, Bob Miller wrote:
On Sat, 03 Nov 2007 17:52:26 -0700, Steve
wrote:

I pulled an old Astron power supply out of mothballs today. It's a
13.8 volt / 20 amp supply (the RS-20A). I find that there's a
noticeable hum when I plug it in, and I also notice that a small
output voltage of one volt or so is measureable on it even when it's
turned off and unplugged.

My Astron SS-30M has an adjustment screw on each meter face. Maybe the
needle just needs to be "zeroed" with no voltage applied. Or perhaps
you could check the reading with an external VOM?

bob
k5qwg


The RS-20A isn't metered. I'm measuring the output voltage with a
multimeter.

Steve

Dave wrote:
what does the voltage read when it is turned on? an rs-20a is probably not
so old that caps would go bad, and the low voltage left over when you turn
it off probably means the caps are holding a charge.

Or if anything is externally connected to the power
supply, the left over low voltage can be coming from
that connected device. I have my RS-20 connected to
a deep discharge marine battery. If I forget to
disconnect the battery from the power supply when
I power down the supply, the meter on the supply
displays the battery voltage. I'm told that can
damage the regulator within the supply but that
has never happened to me.
--
73, Cecil http://www.w5dxp.com

Steve wrote:
The RS-20A isn't metered. I'm measuring the output voltage with a
multimeter.

Is anything connected to the supply when you
make that measurement?
--
73, Cecil http://www.w5dxp.com

On Nov 4, 10:17 am, Cecil Moore wrote:
Steve wrote:
The RS-20A isn't metered. I'm measuring the output voltage with a
multimeter.

Is anything connected to the supply when you
make that measurement?
--
73, Cecil http://www.w5dxp.com

No, nothing is connected to the supply when the measurement is made.

Steve

"Cecil Moore" wrote in message
. ..
Dave wrote:
what does the voltage read when it is turned on? an rs-20a is probably
not so old that caps would go bad, and the low voltage left over when you
turn it off probably means the caps are holding a charge.

Or if anything is externally connected to the power
supply, the left over low voltage can be coming from
that connected device. I have my RS-20 connected to
a deep discharge marine battery. If I forget to
disconnect the battery from the power supply when
I power down the supply, the meter on the supply
displays the battery voltage. I'm told that can
damage the regulator within the supply but that
has never happened to me.
--
73, Cecil http://www.w5dxp.com

I have not done the modification to one, but here is a modification for the
floating batteries.

http://www.repeater-builder.com/astr...rsbattmod.html

http://www.repeater-builder.com/astr...n-rsbatmod.jpg

There is much info on the Astrom supplies he

http://www.repeater-builder.com/astr...ron-index.html