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Hi TPA team I was using the buffalo DAC III since april 2012 with no problems. (and great pleasure) That's my configuration But one day, the dac decided to not work properly again, and I can't figure out why. All my FLAC files sounds like bad mp3, with a lot of saturation. (but non humm) I have another DAC at home and everything is fine with this one. I tried to investigate the problem but I found every was OK: - Current and voltage are OK on the Placid 2.0.1 - Current and voltage are OK on the Placid HD-PB - AVCC and Trident delivered correct voltage - I tried to hard reset the DAC - I verified connections I don't know if the problem comes from the DAC or from the I/V output stage. How can I determine that ? What kind of test can I do ? Do you think that my buffalo is dead ? Do I need to upgrade the DAC firmware and how to do that ? Thank you alpaga
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Originally Posted by: alpagas  Hi TPA team
- I tried to hard reset the DAC
No need to, it happens every time you power cycle Originally Posted by: alpagas
Do I need to upgrade the DAC firmware and how to do that ?
No need to. Firmware doesn't go bad (well it does, every thing goes bad, you just have to wait long enough - but it unlikely) -o- You can rule out the BAL-SE stage by using the BAL out. Use a cap in series with each output and test with a cheap earphone. You can rule out the I/V stage by testing the DAC in voltage out mode (I/V unconnected) Again use a cap in series with each output. Edited by user Saturday, May 24, 2014 8:49:28 AM(UTC)
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Originally Posted by: avr300
You can rule out the BAL-SE stage by using the BAL out. Use a cap in series with each output and test with a cheap earphone.
You can rule out the I/V stage by testing the DAC in voltage out mode (I/V unconnected)
Again use a cap in series with each output.
Thank you for your suggestion I used this to test the voltage out mode of the dac.  Everything is ok at the dac output. I suppose that my problem comes from I/V Y III stage. How can I test it correctly ? Thanks a lot
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Same way as described.
The phrase "You can rule out the BAL-SE stage by using the BAL out" should have been "You can rule out the BAL-SE stage of the IVYIII by using the BAL out".
Pls. make sure you understand how to connect a single ended earphone to a balanced output.
As I see it, you're using one phase output referenced to gnd (pr. channel) Right?
Using the signal between +- terminals of the BAL output header is the way to do it - better than taking + and gnd (or - and gnd)
BUT - since the earphone has a shared gnd between left and right channel, using the above method of connecting will cause a short between the L-R BAL output (remember the shared gnd of the earphone)
You can however use the connections schema, but you have to listen to one channel at the time. That way, you don't short circuit.
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I've just done the test you recommend.
Output signals on L and R BAL output are ok but not good on the SE output.
Perhaps it comes from chip THS4131.
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The BAL-SE OPAMP is IC5, a LM4562 (if the IVY is in stock trim).
One more thing to check is the relay. Is the relay functional (clicks when applying power) ?
The relay only applies to SE output.
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 1 user thanked avr300 for this useful post.
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Originally Posted by: avr300 The BAL-SE OPAMP is IC5, a LM4562 (if the IVY is in stock trim).
One more thing to check is the relay. Is the relay functional (clicks when applying power) ?
The relay only applies to SE output. The relay is ok. I change the complete IVY stage and the buffalo works again.  Thanks a lot for your advises
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