Just upgraded to the DX90 from ipod classic + PA2v2 amp setup pairing it with the Shure 846. Have been burning it in for the past 3 days so I'm around the 76 hours mark. With the 2.1.5 firmware, I find that it was kind of bright and fatigue to listen after awhile. After reading this thread...

OK problem solved! It is really the bridge at the positive pad of C5. The little unit is working fine now. Sounds great too!   Thanks all for the help!

Quote: Yep its not the solder. Hopefully this is the problem. Will work on it and update the results. Thanks!

Quote: The reading between 5V and 0V is very small. I removed L1 and there is voltage to the pads again. Measuring the resistance of the L1 pads to ground, the pad nearer to edge gives a reading on the meter, no readings from the top pad. Is this the issue?   Think I found the...

Quote: Sadly I did C8, C14 and C15 too.   By the way, L1 reads around 270ohms to 280ohms when plugged in.   The werid thing is that I had replace a new U2 and the problem still persist. Any chances of a manufacturing defect for the board? Or passive components fried?    

Resistance between 3v3 and 0v keeps climbing when measured, starts off at around a few K ohms. Is this normal?

Ok, have did all the test.   Removing L1 sees 5V to at the input pads. Reinstalling L1 and removing L3 shuts the board down.   Have also removed and reinstalled C5 and C7, no luck. Removing the LED and R5 also did not help.   I had a spare U2 from another project and swap that in...

Quote: I have desoldered the mini USB connector and switch to wiring a USB cable to the board. Had gave the board another scrub prior to testing.   Roger that, will check the board again as ShinyFalcon suggested and do the L1 and L3 test.

Ok, will go thru those tomorrow.   No problems for the cable itself as prior wiring it onto the board, its supplying 5v w/o problems.   So basically I will be looking at components from L1 to the point the 5V enters U2 right? C5, C7 and U2 itself for bridges, how about the LED and R5?  

Have desoldered the connector off the board, wired the USB cable directly to the board, clean up the solder at the crystal and reinstalled C7. Had also checked other components for bridges.   Still no luck, no voltage at 5V, 0V or 3V3 pads. Now this is getting werid...

Plugging it into my work PC running on Windows XP gives this error message, 'A USB device has exceeded the power limits of its hub port.' The port is shutdown after that and had to be reset to reactivate it.   Have checked all ports for my home PC, no such error when plugging into the USB...

Windows 7, none of the ports are down.   Getting a reading of 0.4 when measuring 5v and 0v pad. Does this means a solder bridge somewhere?   One more thing, are the bridges for the chip as described under the construction steps same as these?  

  Quote: Had did that with another cable which i wired directly to the board. As mentioned earlier that there was voltage when measure at the exposed leads before soldering onto the points on board but once on board, no reading. What are the chances of frying the ICs in this case?

Nice! Are the heatsinks sufficient for the amp?   I had gathered the parts for a point to point build for the 12AU7 version. Only thing stopping me is working out a case design to fit it in.

Have just reflow the joints, passive components and the chips. Still not getting any reading any voltage reading at either 5V or 3v3 even with the USB cable instead of the mini connector. There are voltage reading from the cable before installation onto the board so I assume that the USB points...