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I measured across the DSD switch. On the DIP, I measureed from pin 2 to DVDD and it was 0 ohms with volumite connected and the switch set to Z. I'll double check it tonight (I could be measuring it wrong) to see if I am getting the same measurements at each of the connection points going tot he volumite. But I can't figure out where it would be shorting to DVDD. Sigh... here I thought this would be a quick and easy project 
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You might just have had the switch slightly askew.
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That could be. I making some progress, though. I went back and re-measured everything and I wasn't getting the short across DSD I was seeing last night. Hmmm... note to self - don't do measurements on very small parts when kids are running around screaming behind you and it is getting late.
I went back and re-flowed the solder on the volumite board. There was one joint on the IC socket that looked sketchy, but only under bright light and very close up. I hooked everything back up, still just one mono board, and plugged it back in. Now I am getting sound and some control from the volumite, but it is sporadic. Sometimes the volume changes, sometimes not. Sometimes the sound shuts off. The pot swings from 0 to 3.3V, but I can't tell if it is consistent through the rotation. Any suggestions on what else to look at?
Peter
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How are you powering the volumite?
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I'm connecting VCC and GND on the volumite to VD and G on one of the opus boards. I am powering the opus boards and the volumite from a LCDPS.
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OK. So any intermittent control I had is no gone and I am back to where I was. Sound, but no volume control. Any other suggestions on how to trouble shoot this?
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Maybe you have a damaged switch?
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Well, I've tried both boards independently in mono mode, so it seems odd that the switches on both boards would be damaged. If the switch is damaged I'm outta luck? Or I wire directly to the I/O connectors.
The next question is how likely is it that I wiped out the microcontroller in all of my messing around?
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The controller could only have been damaged if there were a short from SDA or SCL to VDD.
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I'm beginning to wonder if you are right about the switch. With the switches in the Z position, I am getting a measurement of about 22k ohms across the DEEMPH(sdin), Mode, FSEL and OSR switches. This is measured to either DVDD or GND. And I get about 2.5V on the dac side of the switches at these points with the power on (volumite is not connected). Looks like it is the same on both boards (which seems kind of strange).
I'll double check the measurements later (I realize I have reported a variety of measurements previously). If these measurements are correct, am I interpreting it correctly that the switch isn't working right? If that is the case, I guess my other option is to lift the DEEMPH pin on the switch to disconnect it completely?
Thanks for you patience.
Peter
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The fact that the Volumite was working intermittently, really seems to point to a bad solder joint or loose wire.
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I would think so too, but I have touched up all of the solder points on the volumite board and did the same on one of the opus boards - the board I'm testing on (haven't gotten to the 2nd one yet). I'm pretty confident the wire connections are good - I have continuity from pin 7 (scl) of the controller through to DSD on the switch and from pin 5 (sda) on the controller through to DEEMPH.
With the volumite plugged in and the power on, I get a steady 3.2V at SDA and DEEMPH. I get about 24mV at SCL and DSD, which fluctuates as I turn the pot. Is this what should I be seeing here?
I've gone through two volumite boards now with the same issue. I briefly had intermittent control recently, but it was very brief.
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One suggestion I would make is to power the Volimite with 3.3V (not using the regulator on the Volumite) coming from the Opus, not from the LCDPS. What I am thinking is that the opus may be starting up later than the volumite causing a timing issue.
The fact that you situation was "intermittent" definitely does sound like something is lose as Brian stated, but I am just trying to think of other things to try in your situation.
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OK. So here is my dumb question for the evening. I went to tap the 3.3V off dvdd. I measured dvdd at C17 coming out of vrd and I am getting 5V. I also measured dvdd at the switch and it is also 5V. This should be 3.3V, right? So I measured avdd at C18 and I'm getting 3.3V. This is the same on both boards. I think vrd and vra switched.
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All I really meant though was to take the DVDD and not use the on-board reg for the volumite. Is your opus Wm8740 or Wm8741? Edited by user Monday, October 3, 2011 7:41:33 PM(UTC)
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Yes. I understood that. When I was poking around the opus board for the easiest spot to tap 3.3V, I noticed dvdd was measuring 5V at the switch, not 3.3V. I checked the voltage coming out of vrd at C17 and it is 5V. Voltage out of vra at C18 is 3.3V. If the digital side of the dac is operating at 5V, would that have an impact on how the volumite (operating at 3.3V) interacts with it? Should I still try to tap dvdd and run the volumite off of the 5V?
This is the wm8741
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5V is beyond the max specified for the chip (4.5v).
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Agreed. This is a build issue on my part. I will repair/replace your boards if you send them to me.
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Thank you, Brian and Russ. I appreciate your help. What's the best way to get the boards back to you?
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I sent you email earlier. PayPal address maybe?
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