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Hi,
I recently purchased an Opus Dac with spdif WM8804 tranceiver from a friend who upgraded to a new DAC. He wanted to keep his power supply but i have a low-noise regulated supply i can use with the right voltage (7,5v). I started building the complete dac today while only connecting the transceiver to the power supply. I checked voltage before connecting after a couple of minutes to make sure the power supply was OK and voltage remained stable. Measured a constant 7.54v which seems fine. After connecting the transceiver board and powering up the supply nothing happens. All leds stay off.
I'm wondering how to troubleshoot this and looking for some help to get me started. I haven't connected the dac boards to the transceiver for obvious reasons. Any measurements to be made on the board to find out if the wm8804 is broken (or other parts)?
Thanks,
Sander
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A picture would be helpful in diagnosing the problem, or at least a description of the connections.
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Rank: Member
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Hi Brian, The board is currently only connected to the power supply via the GND and V+ connection. No other connections to the board have been made. Sander s666foto attached the following image(s):  P1030059z (Medium).jpg (120kb) downloaded 151 time(s). P1030053 (Medium).JPG (92kb) downloaded 147 time(s).You cannot view/download attachments. Try to login or register.
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Rank: Member
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Location: NL
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Rank: Advanced Member
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You could start by checking orientation of the powerlines. V- to GND and V+ to V+, easy to mix up. Also check voltage when the boards are connected and powered.
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And double check the S/PDIF input and GND are the right way around. I have mixed them up many times.
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OK, I've triple checked voltage levels and power connections (V+/GND) They are correct and give approx. 7,54V. I have not connected the SPDIF connector. Is connecting the SPDIF needed to power up the board (leds)?
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Rank: Administration
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Check the regulator output voltages ate C3 and C6 (to GND)
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Okay, it seems IC3 is not working correctly. You should be seeing 3.3V on C3.
I assume this was working for the guy you bought it from?
You could try touching the solder joints on IC3 with your soldering iron.
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Rank: Member
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OK, i figured something was wrong here when reading the different voltages on ic3 and ic4. It worked with the guy i bought from... I will try your suggestion with the soldering iron to make sure all connections are good. Otherwise i'll have to replace IC3 and take it from there. Is it possible this might have damaged the wm8804?
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Rank: Administration
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I guess it is possible the low voltage reading is due to a damaged WM8804. You could try removing IC3 and adding a temp jumper from C6 (IC4) and see if that works.
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Rank: Member
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I removed ic3 and connected power from ic4 to c3 to supply the wm8804 with 3,3v dvdd. This results in 0,26v over ic4... No leds. Whats next....
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Rank: Administration
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Joined: 10/24/2006(UTC)
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Sounds like a damages WM8804, unless it's a sort somewhere (solder joint under the board?).
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Thanks guys for helping me out so far. No unwanted solder joints or other connection errors are visible. This is also not very likely because the board worked fine before. I gave up and ordered a new transceiver board just now.
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Rank: Member
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Hi Brian,
I ordered a new transceiver board last week but so far no confirmation from TPA. I did receive confirmation of payment from paypal. Could you confirm my order please or did something go wrong in the ordering process?
Thanks!
Sander
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