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? US Robotics Sportster 28,800 Fax modem - PSU requirements.

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ian field
Guest

Thu Jun 10, 2010 9:57 pm   



"Bob Eager" <rde42_at_spamcop.net> wrote in message
news:87d16gFpmfU2_at_mid.individual.net...
Quote:
On Thu, 10 Jun 2010 21:34:14 +0100, ian field wrote:

"Bob Eager" <rde42_at_spamcop.net> wrote in message
news:87cthdFpmfU1_at_mid.individual.net...
On Thu, 10 Jun 2010 17:34:56 +0100, ian field wrote:

IIRC the most common type is 13VAC.

Bear in mind that if it connects to the PC via RS232, it must be
capable of generating plus and minus 12v rails.

I built a board here that runs off 5V. A MAX232 driver/charge pump
drives the serial line fine.


Its the darndest thing tho', I've never yet seen a MAX232 in any of the
modems I've had apart.

Should have made it clear, mine wasn't a modem...it was a clone of a
PDP-8....!


In which case - what the hells it got to do with the OP's question.

John Ray
Guest

Fri Jun 11, 2010 12:03 am   



On 09/06/2010 17:37, David Chapman wrote:
Quote:

I have mislaid the power supply for a US Robotics Sportster 28,800 Fax
Modem (with V34 and V32bis) which I would like to use. This modem
lights up and *appears* to work with a supply of 9 volts DC, drawing
around 200mA, but I'm not yet entirely convinced that it is performing
correctly.

I did some Google searching and haven't managed to find a manual or
any information about the particular unit that I have, but I did see a
similar modem mentioned which requires 9 volt AC to power it. I haven't
yet attempted feeding my modem with AC because I don't want to risk
damaging it..

Can anyone in this NG tell me what the correct voltage should be, and
if it should be AC or DC?
Is there anywhere on the 'net where I might find a User Manual for
this modem? I've searched for one, so far without any success.

Many thanks,

- Dave.


For what it's worth, I have here a US Robotics 56K Faxmodem, complete
with power supply. The label on the latter says "US Robotics SP3a. Input
230v~ plus/minus 10%. Output 9v~ 1000mA"

--
John Ray

Bob Eager
Guest

Fri Jun 11, 2010 12:05 am   



On Thu, 10 Jun 2010 21:57:06 +0100, ian field wrote:

Quote:
"Bob Eager" <rde42_at_spamcop.net> wrote in message
news:87d16gFpmfU2_at_mid.individual.net...
On Thu, 10 Jun 2010 21:34:14 +0100, ian field wrote:

"Bob Eager" <rde42_at_spamcop.net> wrote in message
news:87cthdFpmfU1_at_mid.individual.net...
On Thu, 10 Jun 2010 17:34:56 +0100, ian field wrote:

IIRC the most common type is 13VAC.

Bear in mind that if it connects to the PC via RS232, it must be
capable of generating plus and minus 12v rails.

I built a board here that runs off 5V. A MAX232 driver/charge pump
drives the serial line fine.


Its the darndest thing tho', I've never yet seen a MAX232 in any of
the modems I've had apart.

Should have made it clear, mine wasn't a modem...it was a clone of a
PDP-8....!


In which case - what the hells it got to do with the OP's question.

It shows that a 5V supply could be sufficient, depending on circuitry. Do
keep up.



--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

Cydrome Leader
Guest

Fri Jun 11, 2010 2:31 am   



In sci.electronics.equipment Cydrome Leader <presence_at_mungepanix.com> wrote:
Quote:
In sci.electronics.equipment David Chapman <dave_at_minda.co.uk> wrote:

I have mislaid the power supply for a US Robotics Sportster 28,800 Fax
Modem (with V34 and V32bis) which I would like to use. This modem
lights up and *appears* to work with a supply of 9 volts DC, drawing
around 200mA, but I'm not yet entirely convinced that it is performing
correctly.

I did some Google searching and haven't managed to find a manual or
any information about the particular unit that I have, but I did see a
similar modem mentioned which requires 9 volt AC to power it. I haven't
yet attempted feeding my modem with AC because I don't want to risk
damaging it..

Can anyone in this NG tell me what the correct voltage should be, and
if it should be AC or DC?
Is there anywhere on the 'net where I might find a User Manual for
this modem? I've searched for one, so far without any success.

Many thanks,

- Dave.


I can check when I get home. I have boxes of those things.

an original USR power adapter P/N 1.015.1286 = 9VAC 1000mA

that's the same power adapter for any of the 28.8 and 33.6 modems I have
here.

David Chapman
Guest

Fri Jun 11, 2010 7:55 am   



In message <4qQPn.130559$3B3.75402_at_hurricane>, Sheila
<nospammers_at_blueyonder.co.uk> writes
Quote:

"David Chapman" <dave_at_minda.co.uk> wrote in message
news:FARW7EBZN8DMFwya_at_chassis.demon.co.uk...

I have mislaid the power supply for a US Robotics Sportster 28,800 Fax
Modem (with V34 and V32bis) which I would like to use. This modem
lights up and *appears* to work with a supply of 9 volts DC, drawing
around 200mA, but I'm not yet entirely convinced that it is performing
correctly.

I did some Google searching and haven't managed to find a manual or
any information about the particular unit that I have, but I did see a
similar modem mentioned which requires 9 volt AC to power it. I haven't
yet attempted feeding my modem with AC because I don't want to risk
damaging it..

Can anyone in this NG tell me what the correct voltage should be, and
if it should be AC or DC?
Is there anywhere on the 'net where I might find a User Manual for
this modem? I've searched for one, so far without any success.

Many thanks,

- Dave.

--
David C.Chapman - (dcchapman_at_minda.co.uk)
--------------------------------------------------------------------------


Have you tried contacting a support technician
http://www.usr-emea.com/support/s-email-techie-unkg.asp?loc=unkg

Alternatively, search for the 33.6 version manual - which was the same
hardware with a firmware update.

Good Luck, Sheila


Well, here's the definitive response that I've now received from US

Robotics:-

"Based on the FCC number CJE-0268 that you gave us is from the model
number USR0839. If you have this model number then the specification of
the power supply is 20V AC .5A."

So, the correct voltage WAS somewhere between 9 volts DC and 20 volts
AC ;-)

And so to bed! Many thanks to all those who contributed to this
posting.

All the best - Dave

--
David C.Chapman - (dcchapman_at_minda.co.uk)
--------------------------------------------------------------------------

ian field
Guest

Fri Jun 11, 2010 6:31 pm   



"Bob Eager" <rde42_at_spamcop.net> wrote in message
news:87d9e0FpmfU3_at_mid.individual.net...
Quote:
On Thu, 10 Jun 2010 21:57:06 +0100, ian field wrote:

"Bob Eager" <rde42_at_spamcop.net> wrote in message
news:87d16gFpmfU2_at_mid.individual.net...
On Thu, 10 Jun 2010 21:34:14 +0100, ian field wrote:

"Bob Eager" <rde42_at_spamcop.net> wrote in message
news:87cthdFpmfU1_at_mid.individual.net...
On Thu, 10 Jun 2010 17:34:56 +0100, ian field wrote:

IIRC the most common type is 13VAC.

Bear in mind that if it connects to the PC via RS232, it must be
capable of generating plus and minus 12v rails.

I built a board here that runs off 5V. A MAX232 driver/charge pump
drives the serial line fine.


Its the darndest thing tho', I've never yet seen a MAX232 in any of
the modems I've had apart.

Should have made it clear, mine wasn't a modem...it was a clone of a
PDP-8....!


In which case - what the hells it got to do with the OP's question.

It shows that a 5V supply could be sufficient, depending on circuitry. Do
keep up.

Why would I want to keep up with an irrelevance.

Cydrome Leader
Guest

Fri Jun 11, 2010 7:23 pm   



In sci.electronics.equipment David Chapman <dave_at_minda.co.uk> wrote:
Quote:
In message <4qQPn.130559$3B3.75402_at_hurricane>, Sheila
nospammers_at_blueyonder.co.uk> writes

"David Chapman" <dave_at_minda.co.uk> wrote in message
news:FARW7EBZN8DMFwya_at_chassis.demon.co.uk...

I have mislaid the power supply for a US Robotics Sportster 28,800 Fax
Modem (with V34 and V32bis) which I would like to use. This modem
lights up and *appears* to work with a supply of 9 volts DC, drawing
around 200mA, but I'm not yet entirely convinced that it is performing
correctly.

I did some Google searching and haven't managed to find a manual or
any information about the particular unit that I have, but I did see a
similar modem mentioned which requires 9 volt AC to power it. I haven't
yet attempted feeding my modem with AC because I don't want to risk
damaging it..

Can anyone in this NG tell me what the correct voltage should be, and
if it should be AC or DC?
Is there anywhere on the 'net where I might find a User Manual for
this modem? I've searched for one, so far without any success.

Many thanks,

- Dave.

--
David C.Chapman - (dcchapman_at_minda.co.uk)
--------------------------------------------------------------------------


Have you tried contacting a support technician
http://www.usr-emea.com/support/s-email-techie-unkg.asp?loc=unkg

Alternatively, search for the 33.6 version manual - which was the same
hardware with a firmware update.

Good Luck, Sheila


Well, here's the definitive response that I've now received from US
Robotics:-

"Based on the FCC number CJE-0268 that you gave us is from the model
number USR0839. If you have this model number then the specification of
the power supply is 20V AC .5A."

I don't believe that info at all. There's only two screws holding the
modem together so you can check the filter caps if you want.

first off, that's not the modem you have. You have a 28.8 sporters so it's
very old, and not the latest 33.6 they may be selling now which they may
have given you specs for.

none of the 28.8 or first 33.6 sportsters used 20 volt adapters. Only
couriers did.

They still make couriers but switched from AC adapters to DC switching
power supplies and changed the power connector several times.

David Chapman
Guest

Mon Jun 14, 2010 10:07 am   



In message <hutntd$6jm$1_at_reader1.panix.com>, Cydrome Leader
<presence_at_MUNGEpanix.com> writes
Quote:
In sci.electronics.equipment David Chapman <dave_at_minda.co.uk> wrote:
In message <4qQPn.130559$3B3.75402_at_hurricane>, Sheila
nospammers_at_blueyonder.co.uk> writes

"David Chapman" <dave_at_minda.co.uk> wrote in message
news:FARW7EBZN8DMFwya_at_chassis.demon.co.uk...

I have mislaid the power supply for a US Robotics Sportster 28,800 Fax
Modem (with V34 and V32bis) which I would like to use. This modem
lights up and *appears* to work with a supply of 9 volts DC, drawing
around 200mA, but I'm not yet entirely convinced that it is performing
correctly.

I did some Google searching and haven't managed to find a manual or
any information about the particular unit that I have, but I did see a
similar modem mentioned which requires 9 volt AC to power it. I haven't
yet attempted feeding my modem with AC because I don't want to risk
damaging it..

Can anyone in this NG tell me what the correct voltage should be, and
if it should be AC or DC?
Is there anywhere on the 'net where I might find a User Manual for
this modem? I've searched for one, so far without any success.

Many thanks,

- Dave.

--
David C.Chapman - (dcchapman_at_minda.co.uk)
--------------------------------------------------------------------------


Have you tried contacting a support technician
http://www.usr-emea.com/support/s-email-techie-unkg.asp?loc=unkg

Alternatively, search for the 33.6 version manual - which was the same
hardware with a firmware update.

Good Luck, Sheila


Well, here's the definitive response that I've now received from US
Robotics:-

"Based on the FCC number CJE-0268 that you gave us is from the model
number USR0839. If you have this model number then the specification of
the power supply is 20V AC .5A."

I don't believe that info at all. There's only two screws holding the
modem together so you can check the filter caps if you want.

first off, that's not the modem you have. You have a 28.8 sporters so it's
very old, and not the latest 33.6 they may be selling now which they may
have given you specs for.

none of the 28.8 or first 33.6 sportsters used 20 volt adapters. Only
couriers did.

They still make couriers but switched from AC adapters to DC switching
power supplies and changed the power connector several times.


I can now finally put this discussion to bed since I've managed to
find the actual PSU for the USR Sportster 28,800 Fax modem.

It is marked as producing 18 volts AC at 500mA.

My thanks again to all in this NG who offered suggestions.

- Dave

--
David C.Chapman - (dcchapman_at_minda.co.uk)
--------------------------------------------------------------------------

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