Help with ToubleShooting DAC

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morganc

Help with ToubleShooting DAC
« on: 17 Sep 2019, 03:22 pm »
Hi Guys (if this is inappropriate for this circle, Mods please move).
I'm looking for help diagnosing a problem.  Here it goes:

 
I have a non modded tube Dac.

There is a scratchy noise in one speaker only.  It is worse when I first turn the DAC on, and can scratch and pop for 30-90 seconds.  If I leave the Dac on for a day, the scratchiness almost disappears.  It does not change with tube changes or cable changes or with adjusting any cables other than When I change RCA cables from Right to Left, it changes Speaker.  It does not change when I change amps or speakers, so I know it is something inside the DAC.  It is a rapid scratchy sound that lasts for 1-2 seconds and then stops.   When I first turn it on, it also sounds a bit fuzzy, as if playing an LP and the needle has hit the edge of the recording, with just a low level hiss.  The hiss and the acratchiness both disappate with time.

I am not an EE, but have decent skills....any thoughts? 

Thanks in advance.

morganc

Re: Help with ToubleShooting DAC
« Reply #1 on: 17 Sep 2019, 03:51 pm »
Update:  the manufacturer thinks it is the DAC chip and recommends swapping them to see if that effects the noise.   I'll do that later today. 
Morgan