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The IC2 header on Buf II may conveniently be used to provide power for the volumite.
Which of the Trident regs are supplying this power? The 3V3 VD_XO reg?
I have a B2 that I believe to be dead and the single odd thing I measure is 1.95V on the DVCC pin of the I2C header.
Identical BII connected and configured identically correctly measures 3V3. Hmm....
Nic
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Nic..
Unsolder the trident and jump the bead-pads.
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Tried that with the same result.....
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Any idea where I get those 1.95V from? Was like that after installing tridents and is the same after removing them and re-jumpering the bead-pads.
Never tested the BII board before installing...
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Sounds like a short or an ESD damaged DAC chip. Thoroughly inspect the entire board for shorts.
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Will do (again). My suspicion is indeed a damaged DAC chip but its not clear to me why that should affect the voltage on the DVCC pin of the I2C header. Is this pin fed by the DAC chip?
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No, the DVCC pin of the I2C header is connected to the DVCC power supply (stock or Trident) and so is the DAC. So if DAC (or something else) is pulling way too much current (say a short) then you could see what you are seeing.
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I get what you mean and that was my interpretation too. What puzzles me is just that I do not measure this voltage drop also on the DVCC supply output. I will investigate and let you know if I find an explanation....... meanwhile I'm looking for a replacement board.
Cheers,
Nic
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Rank: Administration
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Perhaps a bad solder joint? Are you saying that the output of the DVCC regulator is staying at 3.3V when mounted on the DAC?
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With the BII back to original state (i.e. no Tridents and jumpers back on):
The DAC draws about 0.3A @ 5.5V
Voltage on supply outputs:
AVCC module: 3.50V (Both sides)
VDD: 1.22V
VDD_XO: 3.28V
DVCC: 3.28V
I2C, ADDR and RESET headers all at 1.95V ???
Any ideas?
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Rank: Advanced Member
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Mystery solved and DAC saved (hopefully)!!!
Close inspection revealed the absence of the "L2" SMD component on this BII board. Solder was there but no trace of component.
Assuming that this component, like the other "L" marked ones, is (i.e. was) a jumper-bead I shorted the pads with a bit of wire.....
Voltages on I2C, ADDR and RESET headers went back to 3V3 and I now get a lock with a source connected!!!
A bad solder joint? Yes - but not one of mine :-)
Cheers,
Nic
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