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69838Re: RXTX ensemble Trouble

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  • Jaco Le roux
    Nov 8, 2012
    • 0 Attachment
      Hi Alan,

      OMG, Something happened and now I have found that the two FTS3253 IC has blown, I have tested it on board with my DMM and receive a full continuity on the meter so I have removed the two 3253's and tested it again.

      Pins shorting on one of them, pin 8 to pin 14 and the other one pin 8 to pin 14 & 15.

      Now my problem is that there aren't any suppliers locally for this IC's... Darn...

      I think That I will have to order another Kit form Tony and maybe ask him if he could in someway add some extra parts in that one. It is just to expensive to only ship a few parts for the other side.

      Thank you for all the help and hopefully I will get it fix when I receive some new parts...

      73'
      Jaco de ZS6PX

      --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
      >
      >
      > ----- Original Message -----
      > Subject: [softrock40] Re: RXTX ensemble Trouble
      >
      > Jaco,
      >
      > Lots of figures!
      > The trouble when twisting the board seems to be something around U5 or U10. Somewhere around the QSD 1 line there must be a bad
      > joint, maybe a crack in a track. Or maybe something shorting, even a whisker of PCB material like we've seen on other boards
      > recently but only connecting intermittently.
      > You do not mention pin U5 12, that is connected to pin 6.
      >
      > The U8 voltage change, I'm not sure. The voltage on those pins is fed through from pins 7,9 when it is clocking. So it may be
      > associated with whatever the above fault turns out to be.
      >
      > With U6 and 7, the votages on pins 3 and 5 all come from the divider R21/R22.
      > So for them to be wrong the resistors could be of wrong value.
      > Possible faulty IC, raise each pin one by one, see if R21 hairpin goes to 2V5.
      > Possible faulty capacitors, C58, 59, 10.
      > The voltage here will affect all others on the ICs so must be correct.
      >
      > Yes, it is annoying when things go wrong. But maybe one day you will be like me, disappointed when something works first time. What
      > do I do next?? This is where you begin to learn things.
      >
      > 73 Alan G4ZFQ
      >
      > > All is fine with the resistors, but I have done a test on the IC's.
      > >
      > > USB & 12volt connected
      > >
      > > U11:
      > > pin1 = 2.63
      > > pin2 = 2.54
      > > pin3 = 2.54
      > > pin4 = 0
      > > pin5 = 2.54
      > > pin6 = 2.54
      > > pin7 = 2.74
      > > pin8 = 5.05
      > >
      > > U10
      > > Pin 8 = 0
      > > Pins 1 and 15 (PTT OFF) = 0
      > > Pin 2 (from Divider) = 2.5
      > > Pin 14 (from Divider) = 2.53 (sometimes I measure 5.05 checked for shorts )
      > > Pin 7 (to OpAmp) Vdc = 2.54
      > > Pin 9 (to OpAmp) Vdc = 2.54
      > > Pin 16 (Vdd) Vdc = 5.05
      > > Pins 1 and 15 (PTT ON) = 5.05
      > >
      > > U6 & U7 ( This is where I found a problem )
      > >
      > > Left IC, Pin 1 Vdc = 0.3
      > > Left IC, Pin 2 Vdc = 0.3
      > > Left IC, Pin 3 Vdc = 0.3
      > > Left IC, Pin 4 Vdc = 0
      > > Left IC, Pin 5 Vdc = 0.3
      > > Left IC, Pin 6 Vdc = 0.3
      > > Left IC, Pin 7 Vdc = 0.3
      > > Left IC, Pin 8 Vdc = 5.05
      > > Right IC, Pin 1 Vdc = 0.3
      > > Right IC, Pin 2 Vdc = 0.3
      > > Right IC, Pin 3 Vdc = 0.3
      > > Right IC, Pin 4 Vdc = 0
      > > Right IC, Pin 5 Vdc = 0.3
      > > Right IC, Pin 6 Vdc = 0.3
      > > Right IC, Pin 7 Vdc = 0.3
      > > Right IC, Pin 8 Vdc = 5.05
      > >
      > > U8 ( Did check for any dry joints just can't find any, re-soldered the board )
      > >
      > > A: Pin 2 Vdc = 2.55
      > > B: Pin 14 Vdc = 2.50
      > > C: Pin 7 (R30 hairpin) Vdc = 2.02
      > > D: Pin 9 (R31 hairpin) Vdc = 2.02
      > > E: Pin 13 (R25 hairpin) Vdc = (Starts at 2volt then decrease, voltage increase if PCB get's twisted)
      > > F: Pin 10 (R26 hairpin) Vdc = (Starts at 2volt then decrease, voltage increase if PCB get's twisted)
      > > G: Pin 12 (R27 hairpin) Vdc = (Starts at 2volt then decrease, voltage increase if PCB get's twisted)
      > > H: Pin 11 (R28 hairpin) Vdc = (Starts at 2volt then decrease, voltage increase if PCB get's twisted)
      > >
      > > U5
      > >
      > > At U5
      > >
      > > R13 hairpin (wrt regular ground) Vdc = 2.51
      > > R14 hairpin (wrt regular ground) Vdc = 5.05
      > >
      > > Pin 1 (blue point) Vdc = 5.05
      > > Pin 2 (yellow point) Vdc = 2.48
      > > Pin 3 (yellow point) Vdc = 2.52
      > > Pin 4 (blue point) Vdc = 5.05
      > > Pin 5 (yellow point) Vdc = 2.5
      > > Pin 6 (yellow point) Vdc = 2.54 (sometimes 5.05, twist PCB then voltage back to 2.54)
      > > Pin 7 (regular ground) Vdc = 0
      > > Pin 8 (yellow point) Vdc = 2.55
      > > Pin9 (yellow point) Vdc = 2.5
      > > Pin 10 (blue point) Vdc = 5.05
      > > Pin 11 (yellow point) Vdc = 2.52
      > > Pin 12 (yellow point) Vdc = 2.54
      > > Pin 11 (blue point) Vdc = 5.05
      > > Pin 14 (blue point) Vdc = 5.05
      > >
      > > Si570
      > >
      > > pin1 = 3.28
      > > pin2 = 3.28
      > > pin3 = 0
      > > pin4 = 1.61
      > > pin5 = 0.3
      > > pin6 = 3.29
      > > pin7 = 3.29
      > > pin8 = 0.930
      > >
      >
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