Snom 300

Discussion in 'UK VOIP' started by Iain, Nov 28, 2011.

  1. Iain

    Iain Guest

    I've had this phone for about 3 years with no problems until today.
    The display was blank and no dial tone. Checked the power supply and
    it's giving 5.2v Plugged cord back into phone and it started to boot up
    then went off again. Did this 3 or 4 times and it suddenly started
    working again.
    Anyone got an idea as to what is happening?
    Regards,

    Iain
    Iain, Nov 28, 2011
    #1
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  2. Iain

    Bodincus Guest

    From: Iain · : · Date: 28/11/11 09:32
    >
    > I've had this phone for about 3 years with no problems until today.
    > The display was blank and no dial tone. Checked the power supply and
    > it's giving 5.2v Plugged cord back into phone and it started to boot up
    > then went off again. Did this 3 or 4 times and it suddenly started
    > working again.
    > Anyone got an idea as to what is happening?
    > Regards,
    >
    > Iain

    Check that the voltage output from the power supply is "clean".
    One of the capacitors that filters the ripple and levels the voltage
    might have gone pop, and the current is not DC, but some DC with a 50Hz
    AC on top.
    Measure the power source output with the voltmeter set to AC: it must
    read zero, otherwise the PSU is busted.

    If that's not the case, is you phone on a public IP, or is the web
    interface accessible from the public 'net?
    In this case, beware of hacking. *NEVER* put your VoIP phone on a public
    IP - despite what many "professionals" recommend it.
    Shield ALL of your phones behind a NAT/firewall, and open just the ports
    you need (SIP and RTP) to the IPs of the provider(s) you register to. If
    you use an Outbound Proxy this might even be unnecessary.

    Keep the firmware version up to date to the latest iteration.
    The most stable version for snom 300's is 7.3.30: it isn't the latest
    (there's an 8.4.32 out, but it's still a bit immature).
    Have a look here > http://wiki.snom.com/Snom300/Firmware
    and follow the instructions.

    Cheers
    --
    ßodincµs - The Y2K Druid
    Bodincus, Nov 28, 2011
    #2
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  3. Iain

    Iain Guest

    On 28/11/2011 12:20, Bodincus wrote:
    > From: Iain · : · Date: 28/11/11 09:32
    >>
    >> I've had this phone for about 3 years with no problems until today.
    >> The display was blank and no dial tone. Checked the power supply and
    >> it's giving 5.2v Plugged cord back into phone and it started to boot up
    >> then went off again. Did this 3 or 4 times and it suddenly started
    >> working again.
    >> Anyone got an idea as to what is happening?
    >> Regards,
    >>
    >> Iain

    > Check that the voltage output from the power supply is "clean".
    > One of the capacitors that filters the ripple and levels the voltage
    > might have gone pop, and the current is not DC, but some DC with a 50Hz
    > AC on top.
    > Measure the power source output with the voltmeter set to AC: it must
    > read zero, otherwise the PSU is busted.
    >
    > If that's not the case, is you phone on a public IP, or is the web
    > interface accessible from the public 'net?
    > In this case, beware of hacking. *NEVER* put your VoIP phone on a public
    > IP - despite what many "professionals" recommend it.
    > Shield ALL of your phones behind a NAT/firewall, and open just the ports
    > you need (SIP and RTP) to the IPs of the provider(s) you register to. If
    > you use an Outbound Proxy this might even be unnecessary.
    >
    > Keep the firmware version up to date to the latest iteration.
    > The most stable version for snom 300's is 7.3.30: it isn't the latest
    > (there's an 8.4.32 out, but it's still a bit immature).
    > Have a look here > http://wiki.snom.com/Snom300/Firmware
    > and follow the instructions.
    >
    > Cheers


    Many thanks for the information.
    The 5vDC supply is quite clean as far as I can tell.
    I updated the firmware after I remembered the username and password (I
    hadn't accessed the web interface for over a year). Had an "OH Shit"
    moment when the phone display went blank for what seemed an awfully long
    time, but all seems to be well now.
    Regards
    Iain
    Iain, Nov 28, 2011
    #3
  4. Iain

    McBart Guest

    On 2011-11-28 13:20:42 +0100, Bodincus said:

    > From: Iain · : · Date: 28/11/11 09:32
    >>
    >> I've had this phone for about 3 years with no problems until today.
    >> The display was blank and no dial tone. Checked the power supply and
    >> it's giving 5.2v Plugged cord back into phone and it started to boot up
    >> then went off again. Did this 3 or 4 times and it suddenly started
    >> working again.
    >> Anyone got an idea as to what is happening?
    >> Regards,
    >>
    >> Iain

    > Check that the voltage output from the power supply is "clean".
    > One of the capacitors that filters the ripple and levels the voltage
    > might have gone pop, and the current is not DC, but some DC with a 50Hz
    > AC on top.
    > Measure the power source output with the voltmeter set to AC: it must
    > read zero, otherwise the PSU is busted.



    A voltmeter set to AC will also measure DC (Its just a DC meter with
    rectifier and a AC calibrated scale.
    Easiest way is to swap your power supply for a know working one. An
    other way is to monitor the DC with a oscilloscope under load and watch
    for excessive ripple ( greater than about 10%)



    >
    > If that's not the case, is you phone on a public IP, or is the web
    > interface accessible from the public 'net?
    > In this case, beware of hacking. *NEVER* put your VoIP phone on a public
    > IP - despite what many "professionals" recommend it.
    > Shield ALL of your phones behind a NAT/firewall, and open just the ports
    > you need (SIP and RTP) to the IPs of the provider(s) you register to. If
    > you use an Outbound Proxy this might even be unnecessary.
    >
    > Keep the firmware version up to date to the latest iteration.
    > The most stable version for snom 300's is 7.3.30: it isn't the latest
    > (there's an 8.4.32 out, but it's still a bit immature).
    > Have a look here > http://wiki.snom.com/Snom300/Firmware
    > and follow the instructions.
    >
    > Cheers



    --

    McBart
    McBart, Nov 28, 2011
    #4
  5. Iain

    Bodincus Guest

    From: McBart · : · Date: 28/11/11 19:18
    > A voltmeter set to AC will also measure DC (Its just a DC meter with
    > rectifier and a AC calibrated scale.
    > Easiest way is to swap your power supply for a know working one. An
    > other way is to monitor the DC with a oscilloscope under load and watch
    > for excessive ripple ( greater than about 10%)


    Readouts on a digital voltmeter don't work like that.
    When you select a DC reading, the current is fed directly to a reference
    resistor array in the ASIC - sometimes there's a further external high
    power shunt resistor when measuring high values of voltages and currents
    - while if you select an AC reading the current is filtered through a
    double rectifier (usually a diode bridge) and a capacitor, then applied
    to the reference resistor array in the ASIC and then the readout is
    extrapolated through a formula.

    The result is that if you read AC from a DC source it's pure ripple.
    Some cheap digital voltmeters only have one diode rectifier, so you get
    one reading with AC+DC with the probes in one way, and only AC in the other.
    A perfectly clean DC source must have a reading of 0V AC on a digital
    multimeter.

    I don't know if there's somebody that still has an analogue multimeter
    sitting in the back of a drawer, a decent digital one comes at £20 so
    I'm assuming we're on digital here.
    --
    ßodincµs - The Y2K Druid
    Bodincus, Nov 29, 2011
    #5
  6. Iain

    McBart Guest

    On 2011-11-29 13:43:46 +0100, Bodincus said:

    > From: McBart · : · Date: 28/11/11 19:18
    >> A voltmeter set to AC will also measure DC (Its just a DC meter with
    >> rectifier and a AC calibrated scale.
    >> Easiest way is to swap your power supply for a know working one. An
    >> other way is to monitor the DC with a oscilloscope under load and watch
    >> for excessive ripple ( greater than about 10%)

    >
    > Readouts on a digital voltmeter don't work like that.
    > When you select a DC reading, the current is fed directly to a reference
    > resistor array in the ASIC - sometimes there's a further external high
    > power shunt resistor when measuring high values of voltages and currents
    > - while if you select an AC reading the current is filtered through a
    > double rectifier (usually a diode bridge) and a capacitor, then applied
    > to the reference resistor array in the ASIC and then the readout is
    > extrapolated through a formula.
    >
    > The result is that if you read AC from a DC source it's pure ripple.
    > Some cheap digital voltmeters only have one diode rectifier, so you get
    > one reading with AC+DC with the probes in one way, and only AC in the
    > other.
    > A perfectly clean DC source must have a reading of 0V AC on a digital
    > multimeter.
    >
    > I don't know if there's somebody that still has an analogue multimeter
    > sitting in the back of a drawer, a decent digital one comes at £20 so
    > I'm assuming we're on digital here.



    Analog meters don't work that way as you mentioned. Assuming things, is
    not 100% accurate as you mention too. Being well informed is the best
    way to know what you actually measuring. That was the main reason of my
    posting. If you literally want to see what you'r looking at use a
    oscilloscope. Nothing beats that :) Simple one's are effective and
    cheap these day's


    --

    McBart
    McBart, Nov 29, 2011
    #6
  7. Iain

    Bodincus Guest

    From: McBart · : · Date: 29/11/11 13:39

    > Analog meters don't work that way as you mentioned. Assuming things, is
    > not 100% accurate as you mention too. Being well informed is the best
    > way to know what you actually measuring. That was the main reason of my
    > posting. If you literally want to see what you'r looking at use a
    > oscilloscope. Nothing beats that :) Simple one's are effective and
    > cheap these day's
    >


    Cheap as much as modding a couple of probes to connect them to your PC
    "Audio IN" and use this for Windoze:

    http://www.zeitnitz.de/Christian/scope_en

    or

    http://www.zelscope.com/

    or this for Linux:

    http://xoscope.sourceforge.net

    When modding/building the probes, be careful to filter high voltages and
    DC currents, to avoid setting fire to your PC though.
    This should help:

    http://xoscope.sourceforge.net/hardware/hardware.html

    --
    ßodincµs - The Y2K Druid
    Bodincus, Nov 29, 2011
    #7
  8. Iain

    Dave Higton Guest

    In message <4ed4d384$0$29319$>
    Bodincus <> wrote:

    > When you select a DC reading, the current is fed directly to a reference
    > resistor array in the ASIC - sometimes there's a further external high
    > power shunt resistor when measuring high values of voltages and currents
    > - while if you select an AC reading the current is filtered through a
    > double rectifier (usually a diode bridge) and a capacitor, then applied
    > to the reference resistor array in the ASIC and then the readout is
    > extrapolated through a formula.


    I see you're not an electronics engineer.

    Dave
    Dave Higton, Nov 29, 2011
    #8
  9. Iain

    Bodincus Guest

    From: Dave Higton · : · Date: 29/11/11 14:38
    > In message<4ed4d384$0$29319$>
    > Bodincus<> wrote:
    >
    >> When you select a DC reading, the current is fed directly to a reference
    >> resistor array in the ASIC - sometimes there's a further external high
    >> power shunt resistor when measuring high values of voltages and currents
    >> - while if you select an AC reading the current is filtered through a
    >> double rectifier (usually a diode bridge) and a capacitor, then applied
    >> to the reference resistor array in the ASIC and then the readout is
    >> extrapolated through a formula.

    >
    > I see you're not an electronics engineer.
    >
    > Dave

    NOW I know why I left this group...
    I AM an electronics engineer.

    Just eff off...
    --
    ßodincµs - The Y2K Druid
    Bodincus, Nov 29, 2011
    #9
  10. Iain

    Dave Higton Guest

    In message <4ed4f9df$0$29398$>
    Bodincus <> wrote:

    > From: Dave Higton · : · Date: 29/11/11 14:38
    > > In message<4ed4d384$0$29319$>
    > > Bodincus<> wrote:
    > >
    > >> When you select a DC reading, the current is fed directly to a reference
    > >> resistor array in the ASIC - sometimes there's a further external high
    > >> power shunt resistor when measuring high values of voltages and currents
    > >> - while if you select an AC reading the current is filtered through a
    > >> double rectifier (usually a diode bridge) and a capacitor, then applied
    > >> to the reference resistor array in the ASIC and then the readout is
    > >> extrapolated through a formula.

    > >
    > > I see you're not an electronics engineer.
    > >
    > > Dave

    > NOW I know why I left this group...
    > I AM an electronics engineer.


    If you were an electronics engineer, you wouldn't write such rubbish.
    Let's take it apart:

    1) What is a "reference resistor array"? "Resistor array", yes.
    "Reference voltage", yes. "Reference resistor array": rubbish.

    2) Cut to the chase: perhaps you mean an attenuator or a voltage
    divider, which is highly likely to be a resistor array (the
    temperature coefficients track better in an array, thus keeping
    the calibration better over a temperature range). But is it in
    an ASIC? No.

    3) High power shunt array when measuring high voltages? No. A
    voltmeter should ideally take no power at all from the circuit
    being measured; real life meters take very little power. (Current
    is harder, so the shunt resistor may dissipate significant power,
    yes.)

    4) You don't filter current through a rectifier. You rectify it.
    You may subsequently filter it, although the measurement system
    itself usually provides enough filtering.

    5) "Double rectifier"? Do you mean a full wave rectifier?

    6) "Usually a diode bridge"? Have you ever tried to design a
    precision rectifier? It's quite a challenge. A diode bridge
    is too difficult to use in any way that doesn't introduce major
    non-linearity; the output is too low for low input voltages.

    That's for starters.

    Dave
    Dave Higton, Nov 29, 2011
    #10
  11. In article <4ed37c9b$0$29367$>,
    Bodincus <> writes:
    > Check that the voltage output from the power supply is "clean".
    > One of the capacitors that filters the ripple and levels the voltage
    > might have gone pop, and the current is not DC, but some DC with a 50Hz
    > AC on top.


    Just had a power supply for a Sipura SPA-3000 die (bought in 2006).
    It's a switched mode PSU. It measured 5V off load, but dropped to
    about 2V on load. It has a pair of 680uF 10V 105C caps in parallel
    across the output, and both had swelled up and had almost no capacity
    left. Replaced with a single 1000uF 10V 105C I happened to have, and
    it's working again now. Just need to find some way to reassemble the
    case safely (I think it was ultrasonic welded before I popped it
    apart, as there's no sign of any solvent glue).

    I've got about 6 of these units, so I guess I need to stock up with
    some replacement caps...

    --
    Andrew Gabriel
    [email address is not usable -- followup in the newsgroup]

    ..
    Andrew Gabriel, Dec 10, 2011
    #11
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