HIFIDIY PCM1798 DAC problem (No Sound)
Dec 30, 2009 at 1:10 PM Thread Starter Post #1 of 4

cha_indian

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I just finished building the DAC but unfortunately i cannot hear any sound.

img0296e.jpg


When i connect the USB, the LED indicator is glowing but not the Coaxial LED indicator. Computer has recognized the DAC and installed the drives too...but i can't hear any sound. There are 4 opamps on this board and two of them are showing no voltage at all.... What could be the possible causes ?? I emailed Candy about this but he/she is yet to respond to my question.

The voltage reg 7805 is getting slightly more than warm....can touch it. But one more SMD reg LM1117 is getting very very hot. It should output a voltage of 3.3V but it is showing only 0.3V...

Did anyone build this DAC ??
 
Dec 30, 2009 at 1:15 PM Post #2 of 4
Here is what i found of this DAC....There are a total of three SMD regs and one 7805. Two SMD regs are working fine as per my multimeter. The one which is at the top is showing output voltage of only 0.3 while it should be 3.3

Could be this the reason for not getting voltage to the OPamps ??
img0297g.jpg
 
Jan 4, 2010 at 9:36 AM Post #3 of 4
I have fixed the voltage issue at the regulator.

But still i find there are no voltages at the indicated opamps.

How to debug this issue ?? Do I need a layout diagram for this ?
 
Jan 4, 2010 at 10:24 AM Post #4 of 4
I left the DAC switched on for one night and now there is no source LED (SLED) glowing ......... the DAC was showing distortion when i played it for the first time and i thought there might be some loose connection.
 

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