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mjock3  
#1 Posted : Monday, August 3, 2015 12:54:36 AM(UTC)
mjock3

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I've got a Legato that has one channel not producing sound. I checked the connections today and all looks good. I also hooked up a small set of headphones (as I set it up to be able to do that) and both channels are working. Any chance I missed something?

Edited by user Monday, August 3, 2015 1:59:35 PM(UTC)  | Reason: Not specified

avr300  
#2 Posted : Monday, August 3, 2015 4:16:09 PM(UTC)
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Originally Posted by: mjock3 Go to Quoted Post
I've got a Legato that has one channel not producing sound. I checked the connections today and all looks good. I also hooked up a small set of headphones (as I set it up to be able to do that) and both channels are working. Any chance I missed something?


Hi.

Pls. explain how?
mjock3  
#3 Posted : Tuesday, August 4, 2015 12:28:25 AM(UTC)
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HP 1,2,3 outputs
Brian Donegan  
#4 Posted : Tuesday, August 4, 2015 2:55:11 PM(UTC)
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Is this a new build, or was it working then failed?
mjock3  
#5 Posted : Wednesday, August 5, 2015 5:55:31 PM(UTC)
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It was working, then failed.
avr300  
#6 Posted : Wednesday, August 5, 2015 6:23:02 PM(UTC)
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If you by saying

"I also hooked up a small set of headphones (as I set it up to be able to do that) and both channels are working"

are sure that the Legato is working - it's time to look upstream.

Lets start real basic. Are you sure that you're feeding the DAC both left and right channel ?
mjock3  
#7 Posted : Wednesday, August 5, 2015 9:09:48 PM(UTC)
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To be honest I have no idea how to check for that. Wouldn't the fact that I can hear both channels using the headphones connected to the HP 1, 2, 3 output of the Legato mean that I have 2 channels of the DAC working?
avr300  
#8 Posted : Thursday, August 6, 2015 5:49:42 AM(UTC)
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Ok, now I understand. So you actually can hear music through the HP connector.

Then I would look upstream (to whatever comes after the Legato). The HP connector is in parallel with the SE outputs.

Of cause you could alway look for bad solder joints and/or bad wiring.
mjock3  
#9 Posted : Thursday, August 6, 2015 7:45:01 PM(UTC)
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Checked out the solder joints & wiring. It looked fine. Am I reading the schematic right that R25 and L1 are on the outputs but not HP output?
avr300  
#10 Posted : Friday, August 7, 2015 6:44:27 PM(UTC)
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I don't think so. I think it's connected as this.

(I could pull the board from my rig - but if your board is in "free air" you might trace the HP output)
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avr300  
#11 Posted : Friday, August 7, 2015 6:54:30 PM(UTC)
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Well, for sure if anyone can, Russ can tell.
Brian Donegan  
#12 Posted : Friday, August 7, 2015 7:26:23 PM(UTC)
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Both the SE Outs and the HP Outs go through L1/L1 and R25/R26. They are they same net, just in a more convenient spot for connecting three wires for headphones.

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Edited by user Friday, August 7, 2015 7:33:13 PM(UTC)  | Reason: Not specified

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mjock3  
#13 Posted : Saturday, August 8, 2015 3:00:50 PM(UTC)
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Thanks for the input, avr300 & Brian. If I put the meter on the output screws I still get nothing, now on both channels. this would rule out wires and jacks, correct?

Edited by user Saturday, August 8, 2015 3:45:18 PM(UTC)  | Reason: Not specified

mjock3  
#14 Posted : Saturday, August 8, 2015 4:09:19 PM(UTC)
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Just checked and I got continuity between hp output and SE output. Something that puzzles me is I also get continuity between SE and Ground at output. This shouldn't be should it?
avr300  
#15 Posted : Saturday, August 8, 2015 6:24:24 PM(UTC)
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Certainly not. Try disconnecting what ever comes after the legato.
mjock3  
#16 Posted : Saturday, August 8, 2015 9:56:09 PM(UTC)
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I have disconnected everything including HP and it still has continuity between SE and Ground connection for output.
avr300  
#17 Posted : Sunday, August 9, 2015 6:58:16 AM(UTC)
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Ohh - remember the relay.

Its there for doing this one purpose - shorting the SE to GND when the Legato is not powered.
Brian Donegan  
#18 Posted : Monday, August 10, 2015 2:52:16 PM(UTC)
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Try measuring continuity between output and GND with the power on (on the non-functioning channel).
mjock3  
#19 Posted : Monday, August 10, 2015 8:57:27 PM(UTC)
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I get a 30 ohm reading.
Brian Donegan  
#20 Posted : Friday, August 14, 2015 2:25:46 PM(UTC)
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I'm not ignoring you, just an incredibly busy week at the day job.... :)

I am a little confused about the symptoms, so I want to clarify the situation:


  • One channel not working: balanced output, SE output, or both?


  • You hear sound from both channels at the headphone output? This means that both channels are working through headphones, but not through the other outputs?



The resistance check I had you do was to confirm that the relay was not keeping the output shunted to ground when operating. It was 30-ohms, not 0-ohms, so you should be okay there.
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