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My Buffalo II/Ivy III has been working fine for years (I can't remember how long it's been now, but I was an early adopter!), but the left channel now produces no sound in either balanced or SE.
All signal connections test fine, and nothing has changed on a visual inspection, but my circuit diagnosing skills are limited to say the least. Any clue where to start?
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Disconnect the non-functional channel from the IVY, and see if you get any output from the Buffalo directly.
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Thanks Brian, I'll try it later/tomorrow. I assume you mean to test the output pads on the Buffalo (which have the connection pins to the Ivy poking through them) for a voltage after disconnecting the wires running to the RCA/XLR sockets from the terminal blocks on the Ivy.
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I mean separating the Buffalo and ivy, if possible. But yes, that is were to measure. Try testing with some Headphones. I use a wire with alligator clips to connect ground on the headphone plug, then probe with the tip for music.
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I disconnected Buffalo and Ivy. Testing the pins on the Buffalo which connect to the Ivy - they all gave me a DC voltage of 1.747 V between GND and +/- except for the (silent) left channel positive pin, which gave a 0 V reading. Is my Buffalo dead? Is there anything else I can do/test?
Thanks again.
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Unfortunately my best guess is - yes it likely is. Especially is the other pin is normal.
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That's rather upsetting. Why would it just die? It's just been sitting there happily doing its thing - it wasn't subjected to any environmental stress. Edited by user Monday, April 30, 2012 8:23:42 PM(UTC)
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Is it possible to have it repaired/replaced?
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I guess that's a no then.
Could I maybe send in my dead Buffalo II and get a reduced price on a Buffalo III instead? I'm DACless!
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So...
it seems to have started working again. Maybe it just needed a rest. Either that or the act of separating Buffalo from Ivy and then re-assembling it, secured something which was adrift. You decide.
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OK, after working fine for a while, the problem has returned. I measured the DAC outputs and they're fine. The signal is reaching the Ivy OK. The Ivy outputs give different results though. The right channel varies AC voltage with changing volume, whereas the left channel remains at a steady 3.6mV.
Any suggestions as to what (and how) to test?
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Maybe an intermittent connection or cold solder joint?
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Originally Posted by: Russ White  Maybe an intermittent connection or cold solder joint? Thanks for replying. Which components are specific to the left channel, just so I can concentrate on those? Edit: Looking at the schematic pretty much answered my question! Time to reflow... Edited by user Friday, July 13, 2012 10:37:42 PM(UTC)
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I re-soldered all left-channel components and now I get no sound from either channel! Signal from Buffalo II is still good and still making it to the Ivy. Power from Placid is still fine. I'm getting just over 2 mV from all outputs. I'm not sure how to test current draw or anything else. I'm stumped. Edited by user Saturday, July 14, 2012 4:29:16 PM(UTC)
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Time for a good picture of both sides of the IVY
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But then you would see how awful my soldering is! I suspect the ICs are fried, but I don't want to shell out for a new PCB until I'm 100% sure.
I was thinking about a Legato, but I have balanced headphones and I can't afford 2 Legatos!
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Originally Posted by: kesgreen But then you would see how awful my soldering is! I suspect the ICs are fried, but I don't want to shell out for a new PCB until I'm 100% sure.
I was thinking about a Legato, but I have balanced headphones and I can't afford 2 Legatos! If your soldering are as awful as you says, then it might be the problem. Why do you suspect the OPAMPs ? Edited by user Sunday, July 15, 2012 7:26:37 AM(UTC)
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Originally Posted by: avr300 Originally Posted by: kesgreen But then you would see how awful my soldering is! I suspect the ICs are fried, but I don't want to shell out for a new PCB until I'm 100% sure.
I was thinking about a Legato, but I have balanced headphones and I can't afford 2 Legatos! If your soldering are as awful as you says, then it might be the problem. Well it's not the neatest - especially as I added more solder on the left in an attempt to counteract a possible dry joint. Originally Posted by: avr300
Why do you suspect the OPAMPs ?
I assume they are the most sensitive/easily damaged components. I have no empirical evidence - I don't know how to gather it.
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OK. So I went back to the Buffalo II board for re-testing. I assumed that since both channels were producing the same voltage, that both channels were fine. This turned out to be wrong. I dug out a headphone socket so I could try Brian's trick mentioned above. From the right channel of the Buffalo board - sound. From the left channel - nothing. So there's a problem with the Buffalo board. Marvellous Anyone have a spare board that they want to sell? 
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Carefully measure the output of the AVCC module.
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