AW-D3 (PCM2706) problem

[pipp0r]

I have buildt the aw-d3 kit, and it worked all fine. But now all of a sudden my computer won't recognise the dac. The diodes is lighting and it all looks fine. Have checked all solder joints but stil no love betwheen the pc and the dac. Any one got any tips?

Info about the dac: http://www.audioworkshop.com.hk/report/d3/d3.html

 

[jkeny]

How is your USB cable connected to the PCB board - through a USB socket? How long was it working before it stopped?

I also have built this kit and it works fine through the PCM2706 internal DAC but no I2S or SPDIF out - also trying to get to the bottom of this

John

 

[pipp0r]

Hi.
They forgot to send me an usb connector so I soldered the usb cabel directly to the board. Red - White - Green - Black (right to left). It worked for about a month. Until that point everything was functional the I2S, spdif and the analog out tda1543 section.

 

[jkeny]

Have you tried to power it off external power? - I saw a thread where if you do this you must ensure D+ connects before power is applied - else chip is damaged.

Someone also posted that his sound developed crackles but this was resolved when he retipped all PCM chip pins with soldering iron - must have been a bad solder joint on one chip.

BTW how did the sound of the internal DAC (Headphone output) compare to TDA1543 sound (when it was working)?

 

[pipp0r]

Hmm yes I had it powered of external power. If what you say about d+ is correct, I might have fried it Is this the pcm2706 chip that might have been damaged ? It makes sense as I mesure 0.5v of the 3.3v points, this indicates that the chip is broken as the internal regulator of the chip is no longer working.

As for sound I did not try the headphone out. But when powering both the usb reciver and the analoge tda1543 of external power it played WERRY good, it gave my EC ECD1 a run for the money.

 

[jkeny]

Yes that's probably the problem - when using external power you need to use a regulator (REG102) with enable pin and connect this to the Vbus power in so when USB connected reg turns on - or you could do this with an and gate.

Are you going to try replacing PCM chip?

 

[pipp0r]

Are you going to try replacing PCM chip?

Hmm I guess I'm out of luck then. If I get my hands on any 2706 chips I might give it a try. But I dont have much confidense in me being able remove and resolder something that small

 

[dsavitsk]

This requirment of these chips is clearly indicated in the datasheet. I would ask for a refund, or at least a new kit, as this is really just a poorly designed project. Short of that, you can see some suggestions on how to, and how not to, remove these chips at: http://www6.head-fi.org/forums/showthread.php?t=174352