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Softrock Lite II - Power Supply Test Fail

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  • kevin_kleinfelter
    I m off to a slow start, and I need some help. I m building a Softrock Lite II, I ve built only the power supply section, and it doesn t test the way wb5rvz
    Message 1 of 6 , Jul 21, 2012
      I'm off to a slow start, and I need some help.  I'm building a Softrock Lite II, I've built only the power supply section, and it doesn't test the way wb5rvz instructions say it should:
      • The instructions say current draw should be < 9 Ma with a 1K resistor and 3-6 mA without.
      • With 12V supplied, I get 2.1 mA whether I use a resistor or not.
      Here's what looks good:
      1. With 12V supplied, I get 4.7 V at the positive lead of C2.
      2. I've inspected the solder joints under lighted 10X magnification, and I don't see a bad joint or a bridge.
      3. I've compared forward and reverse resistance of the D1 with one that's out of circuit.  (I used D1 from a second kit.)  They're pretty close.
      4. I've checked resistance between the negative leads of C1, C2, and C13 and ground, and they're 0 ohms, as is lead 2 of U1.
      5. The banded end of D1 shows zero ohms with pin 1 of U1 and the positive lead of C1.
      6. The positive lead of C2 shows zero ohms with pin 3 of U1.

      I don't know where else to look.  Why wouldn't I get the expected current values?
      TIA

    • Dave Matthews
      Kevin, Those values really don t sound out of line. The current check is to make sure that nothing is shorted. Low values of current are good. I don t have
      Message 2 of 6 , Jul 21, 2012
        Kevin,
         
        Those values really don't sound out of line.  The current check is to make sure that nothing is shorted.  Low values of current are good. 
         
        I don't have the schematic in front of me but if the positive lead of C2 is supposed to be 5 volts then 4.7 volts may be on the low side but it is close enough that I would suspect the calibration of the voltmeter.  I have a very nice digital that was in the lot with an oscilloscope that I bought that is off by at least that much.
         
        If nothing is getting warm I wouldn't worry about it.
         
        Dave
        KB2YWT

        On Sat, Jul 21, 2012 at 9:36 PM, kevin_kleinfelter <kevin@...> wrote:
         

        I'm off to a slow start, and I need some help.  I'm building a Softrock Lite II, I've built only the power supply section, and it doesn't test the way wb5rvz instructions say it should:
        • The instructions say current draw should be < 9 Ma with a 1K resistor and 3-6 mA without.
        • With 12V supplied, I get 2.1 mA whether I use a resistor or not.
        Here's what looks good:
        1. With 12V supplied, I get 4.7 V at the positive lead of C2.
        2. I've inspected the solder joints under lighted 10X magnification, and I don't see a bad joint or a bridge.
        3. I've compared forward and reverse resistance of the D1 with one that's out of circuit.  (I used D1 from a second kit.)  They're pretty close.
        4. I've checked resistance between the negative leads of C1, C2, and C13 and ground, and they're 0 ohms, as is lead 2 of U1.
        5. The banded end of D1 shows zero ohms with pin 1 of U1 and the positive lead of C1.
        6. The positive lead of C2 shows zero ohms with pin 3 of U1.

        I don't know where else to look.  Why wouldn't I get the expected current values?
        TIA


      • Alan
        ... From: Dave Subject: Re: [softrock40] Softrock Lite II - Power Supply Test Fail ... sure that nothing is shorted. Low values of current are good. Yes,
        Message 3 of 6 , Jul 21, 2012
          ----- Original Message -----
          From: "Dave
          Subject: Re: [softrock40] Softrock Lite II - Power Supply Test Fail


          >Those values really don't sound out of line. The current check is to make
          sure that nothing is shorted. Low values of current are good.

          Yes, Robby's values are sometimes a very rough guide. The current is different for individual regulators. Just check the voltage as
          you progress.

          As Dave says your meter may not be particularly accurate. How does it check with a brand new dry cell? I find these usually just
          above 1V5.

          73 Alan G4ZFQ


          I don't have the schematic in front of me but if the positive lead of C2 is
          supposed to be 5 volts then 4.7 volts may be on the low side but it is
          close enough that I would suspect the calibration of the voltmeter. I have
          a very nice digital that was in the lot with an oscilloscope that I bought
          that is off by at least that much.

          If nothing is getting warm I wouldn't worry about it.

          Dave
          KB2YWT

          On Sat, Jul 21, 2012 at 9:36 PM, kevin_kleinfelter <kevin@...>wrote:

          > **
          >
          >
          > I'm off to a slow start, and I need some help. I'm building a Softrock
          > Lite II, I've built only the power supply section, and it doesn't test the
          > way wb5rvz instructions say it should:
          >
          > - The instructions say current draw should be < 9 Ma with a 1K
          > resistor and 3-6 mA without.
          > - With 12V supplied, I get 2.1 mA whether I use a resistor or not.
          >
          > Here's what looks good:
          >
          > 1. With 12V supplied, I get 4.7 V at the positive lead of C2.
          > 2. I've inspected the solder joints under lighted 10X magnification,
          > and I don't see a bad joint or a bridge.
          > 3. I've compared forward and reverse resistance of the D1 with one
          > that's out of circuit. (I used D1 from a second kit.) They're pretty
          > close.
          > 4. I've checked resistance between the negative leads of C1, C2, and
          > C13 and ground, and they're 0 ohms, as is lead 2 of U1.
          > 5. The banded end of D1 shows zero ohms with pin 1 of U1 and the
          > positive lead of C1.
          > 6. The positive lead of C2 shows zero ohms with pin 3 of U1.
          >
          >
          > I don't know where else to look. Why wouldn't I get the expected current
          > values?
          > TIA
          >
          >
          >
        • Kevin Kleinfelter
          I bought a new meter this morning. (The old one had lived a rough life, and I discovered that it was showing absolute nonsense for some of its readings.) The
          Message 4 of 6 , Jul 22, 2012
            I bought a new meter this morning.  (The old one had lived a rough life, and I discovered that it was showing absolute nonsense for some of its readings.) 

            The new one shows 5.07 volts at C2.  It still shows 2.1 mA current draw.

            Thanks for the help.  I tend to take instructions quite literally.  A friend once declared, "Kevin, you are the most German of us all."  ;-)

            On Sunday, July 22, 2012 at 1:16 AM, Alan wrote:


            ----- Original Message -----
            From: "Dave
            Subject: Re: [softrock40] Softrock Lite II - Power Supply Test Fail


            Those values really don't sound out of line. The current check is to make
            sure that nothing is shorted. Low values of current are good.

            Yes, Robby's values are sometimes a very rough guide. The current is different for individual regulators. Just check the voltage as
            you progress.

            As Dave says your meter may not be particularly accurate. How does it check with a brand new dry cell? I find these usually just
            above 1V5.

            73 Alan G4ZFQ


            I don't have the schematic in front of me but if the positive lead of C2 is
            supposed to be 5 volts then 4.7 volts may be on the low side but it is
            close enough that I would suspect the calibration of the voltmeter. I have
            a very nice digital that was in the lot with an oscilloscope that I bought
            that is off by at least that much.

            If nothing is getting warm I wouldn't worry about it.

            Dave
            KB2YWT

            On Sat, Jul 21, 2012 at 9:36 PM, kevin_kleinfelter <kevin@...>wrote:

            **


            I'm off to a slow start, and I need some help. I'm building a Softrock
            Lite II, I've built only the power supply section, and it doesn't test the
            way wb5rvz instructions say it should:

            - The instructions say current draw should be < 9 Ma with a 1K
            resistor and 3-6 mA without.
            - With 12V supplied, I get 2.1 mA whether I use a resistor or not.

            Here's what looks good:

            1. With 12V supplied, I get 4.7 V at the positive lead of C2.
            2. I've inspected the solder joints under lighted 10X magnification,
            and I don't see a bad joint or a bridge.
            3. I've compared forward and reverse resistance of the D1 with one
            that's out of circuit. (I used D1 from a second kit.) They're pretty
            close.
            4. I've checked resistance between the negative leads of C1, C2, and
            C13 and ground, and they're 0 ohms, as is lead 2 of U1.
            5. The banded end of D1 shows zero ohms with pin 1 of U1 and the
            positive lead of C1.
            6. The positive lead of C2 shows zero ohms with pin 3 of U1.


            I don't know where else to look. Why wouldn't I get the expected current
            values?
            TIA



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          • Angus
            I have a similar problem to this guy, however I am not reading any current anywhere. My voltages look good: 11.6V at D1 and 5V at R11. I am running a power
            Message 5 of 6 , Feb 19, 2013
              I have a similar problem to this guy, however I am not reading any current anywhere. My voltages look good: 11.6V at D1 and 5V at R11.

              I am running a power adapter which supplies 12V at .75A

              I have tried testing the current as per the diagram, without the resistor.

              Before building the power stage I soldered all the SMT components on using the reflow process as shown in this video: http://www.youtube.com/watch?v=gu0v8lfLcKg

              It turned out very nicely, with no bridges or bad joints, but I wonder if this circuitry is connected to the power stage somehow. I think R3 is the only point where the power stage connects to the rest of the circuitry and that component has not been installed yet.

              Am I just measuring incorrectly? I attached everything just as in the diagram...

              --- In softrock40@yahoogroups.com, Kevin Kleinfelter <kevin@...> wrote:
              >
              > I bought a new meter this morning. (The old one had lived a rough life, and I discovered that it was showing absolute nonsense for some of its readings.)
              >
              > The new one shows 5.07 volts at C2. It still shows 2.1 mA current draw.
              >
              > Thanks for the help. I tend to take instructions quite literally. A friend once declared, "Kevin, you are the most German of us all." ;-)
              >
              >
              > On Sunday, July 22, 2012 at 1:16 AM, Alan wrote:
              >
              > >
              > > ----- Original Message -----
              > > From: "Dave
              > > Subject: Re: [softrock40] Softrock Lite II - Power Supply Test Fail
              > >
              > >
              > > > Those values really don't sound out of line. The current check is to make
              > > sure that nothing is shorted. Low values of current are good.
              > >
              > > Yes, Robby's values are sometimes a very rough guide. The current is different for individual regulators. Just check the voltage as
              > > you progress.
              > >
              > > As Dave says your meter may not be particularly accurate. How does it check with a brand new dry cell? I find these usually just
              > > above 1V5.
              > >
              > > 73 Alan G4ZFQ
              > >
              > >
              > > I don't have the schematic in front of me but if the positive lead of C2 is
              > > supposed to be 5 volts then 4.7 volts may be on the low side but it is
              > > close enough that I would suspect the calibration of the voltmeter. I have
              > > a very nice digital that was in the lot with an oscilloscope that I bought
              > > that is off by at least that much.
              > >
              > > If nothing is getting warm I wouldn't worry about it.
              > >
              > > Dave
              > > KB2YWT
              > >
              > > On Sat, Jul 21, 2012 at 9:36 PM, kevin_kleinfelter <kevin@... (mailto:kevin@...)>wrote:
              > >
              > > > **
              > > >
              > > >
              > > > I'm off to a slow start, and I need some help. I'm building a Softrock
              > > > Lite II, I've built only the power supply section, and it doesn't test the
              > > > way wb5rvz instructions say it should:
              > > >
              > > > - The instructions say current draw should be < 9 Ma with a 1K
              > > > resistor and 3-6 mA without.
              > > > - With 12V supplied, I get 2.1 mA whether I use a resistor or not.
              > > >
              > > > Here's what looks good:
              > > >
              > > > 1. With 12V supplied, I get 4.7 V at the positive lead of C2.
              > > > 2. I've inspected the solder joints under lighted 10X magnification,
              > > > and I don't see a bad joint or a bridge.
              > > > 3. I've compared forward and reverse resistance of the D1 with one
              > > > that's out of circuit. (I used D1 from a second kit.) They're pretty
              > > > close.
              > > > 4. I've checked resistance between the negative leads of C1, C2, and
              > > > C13 and ground, and they're 0 ohms, as is lead 2 of U1.
              > > > 5. The banded end of D1 shows zero ohms with pin 1 of U1 and the
              > > > positive lead of C1.
              > > > 6. The positive lead of C2 shows zero ohms with pin 3 of U1.
              > > >
              > > >
              > > > I don't know where else to look. Why wouldn't I get the expected current
              > > > values?
              > > > TIA
              > > >
              > >
              > >
              > >
              > >
              > > ------------------------------------
              > >
              > > Yahoo! Groups Links
              > >
              > >
              > >
              > >
              >
            • Alan
              ... Subject: [softrock40] Re: Softrock Lite II - Power Supply Test Fail ... If you have 5V it must be taking current. Only a few mA, but a test meter should be
              Message 6 of 6 , Feb 19, 2013
                ----- Original Message -----
                Subject: [softrock40] Re: Softrock Lite II - Power Supply Test Fail


                >I am not reading any current anywhere. My voltages look good: 11.6V at D1 and 5V at R11.
                >
                > I am running a power adapter which supplies 12V at .75A
                >
                > I have tried testing the current as per the diagram, without the resistor.
                >

                If you have 5V it must be taking current.
                Only a few mA, but a test meter should be able to see it when set to a low range.

                73 Alan G4ZFQ
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