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Re: [sdr-cube] spectrum scope

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  • wb6kwt
    Juha, I think I have a problem with the PCB because I checked between the via from IC4 pin 6 and the via from IC3 pin 96 and have no continuity. I have
    Message 1 of 70 , Feb 5 6:18 PM
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      Juha,

      I think I have a problem with the PCB because I checked between the via from IC4 pin 6 and the via from IC3 pin 96 and have no continuity. I have continuity from IC4 pin 6 to the via, on that track so pin 6 solder is good. I'm checking at the chip pin and not the pad.

      What would be the symptom of IC3 pin 96 not being connected?

      Thanks,

      Bob
      wb6kwt

      On 2/5/2011 4:43 PM, Juha Niinikoski wrote:
       

      Hello Bob
      schematic is correct. Codec chip IC4 DOUT pin#6 (data out) is connected
      to the DSP chip IC3 CSDI pin#96 (data in).

      You most probably still having cold soldering joint or problem with the
      PCB. This particular signal is little bit difficult to follow because
      traces goes partially under the chips. IC4 pin#6 trace is the leftmost
      trace coming out at the bottom side of the chip. You can start to follow it.

      73 Juha oh2nlt

      On 6.2.2011 2:02, wb6kwt wrote:
      > George,
      >
      > Everything seems to be okay with IC9, I've "buzzed" each pin to the
      > component it's connected to.
      >
      > Can you please confirm that IC4 PIN 6 is in fact CSDI and that pin 6
      > should have connection to IC3 pin 96. I'm following the schematic dated
      > 2010.10.31. I don't have connectivity between those to pins going pad to
      > pad. Could be the schematic is in error or I'm misreading it.
      >
      > Bob
      > wb6kwt
      >


    • wb6kwt
      Ok, I need to find the build sheet for this part, I m sure those voltages were fine when I did the first test. I logged each test section on the sheet. Digikey
      Message 70 of 70 , Feb 10 4:25 PM
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        Ok, I need to find the build sheet for this part, I'm sure those voltages were fine when I did the first test. I logged each test section on the sheet.

        Digikey has the part put I hate to order just one chip and pay the postage. I'll re-check the parts connected to pin 6.

        Bob
        wb6kwt

        On 2/10/2011 4:07 PM, fmspinne@... wrote:  


        That low is probably the problem.  That's an inverting input to one of the channels.  You need to try to trace the problem down or replace the device.  Good on hearing 7 MHz.

        Fred



        wb6kwt <wb6kwt@...>
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        02/10/2011 05:54 PM

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        Subject
        Re: [sdr-cube] Still no solution (Update)







         

        Mike, Fred,

        IRT U11 voltages, all of the voltages are correct except pin 6 it is reading low at 1.69V. I touched up pin 6 but no change.

        Fred, yes I do hear the 7mhz signal along with the 28mhz.

        Bob
        wb6kwt

        On 2/10/2011 11:34 AM,
        fmspinne@... wrote:
         


        I concur on the +ve, -ve test.. it's a critical test.  It was fine on mine when I debugged it so I didn't think of it here.  Reflowing isn't a bad idea.  It is what fixed my sr63ng when I couldn't find *anything* else wrong with it.  If you don't see the 2.5V at the places in these places:


        U11, Pins 1, 2, 3, 5, 6 & 7--  Vdc  ~2.5    
        U11, Pin 8  Vdc--  ~5    
        U11, Pin 4  Vdc--  0    


        Then there is no hope that the Op-amp is working properly.


        Hey-- do you also hear a 7.00 MHz signal on your K2?  If not, your divide by four 74AC74 chip is hosed.. you'd get signal through the rig by undersampling if it were bad but it would be GREATLY attenuated.  Check the divide by four circuit as well.  If you have a frequency counter that is a really good way to do it.. but listening for the direct conversion frequency would work fb too.  It should be strong.  If you have a scope and can hook to the 74AC74 output, it should be full TTL swing.  The scope/freq counter is nice as you can check both 90 quadrature phases of the divider are working that way whereas listening on a rig you'll only hear that there is a 7.00 MHz signal.


        Good luck with it.


        Fred W0FMS




        Mike Collins <mikecol@...>
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        02/10/2011 12:59 PM

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        Re: [sdr-cube] Still no solution (Update)









         

        I can reflow the components but I've been over every inch of the board and I'm confident that the FST3253 and LT 6231 are properly solder in. I use a continuity checker that won't destroy the chips, like a DMM might and the probes are needles. I've verified every pin, of both chips are properly soldered.

        As far as the Cube its self, I've verified that I can control the SI570. With the Cube on 7.000mhz I hear a 28.000mhz signal on my K2. I've also verified every pin on the codec too.

        Hi Bob,

        I think you fed audio to the Cube and showed it worked, right??  If so, I guess you are debugging the softrock..

        One good check is the voltages on the +ve, -ve, and output of each op amp.  They should all be roughly 2.5V.  At 0 or 5V is a problem.
        The -ve input kind of checks the FST3253 a bit and the RX BPF transformer since the 2.5V must feed thru them.
        The +ve input is just the R51/R52 divider set at 2.5V.  The opamp outputs should be near 2.5V showing the opamp feedback is working.

        Measure those with a high imped voltmeter and tell us what you have.

        73,  Mike Collins  KF4BQ



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