Loading ...
Sorry, an error occurred while loading the content.

Re: Softrock Lite II - Power Supply Test Fail

Expand Messages
  • 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 1 of 6 , Feb 19, 2013
    • 0 Attachment
      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 2 of 6 , Feb 19, 2013
      • 0 Attachment
        ----- 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
      Your message has been successfully submitted and would be delivered to recipients shortly.