ezDAC v.1.5 Builders Thread

[PJN]

Hi Evan,

The V+ is coming in under the board. It was neater that way.

I took some voltages on the regulators, the pic attached shows what I measured. The layout of the sketch is the same as the layout on the board.

PJN

[ezkcdude]

There's got to either be a short or open circuit somewhere on the board. Or possibly something got fried, but you probably would've realized that by now. The only way to figure out is to probe as much as you can.

[paulb]

It looks like you have all 4 voltages, but the designators (U8, 9,10,11) in your drawing are mixed up. At least they don't seem to match the schematic.

[6h5c]

Check for shorts around the oscillator. If the clock signal is missing, the DAC won't do anything either. If you have a scope around, check the clock signal.

Ray

[PJN]

Hi Paul,

You are right I screwed my drawing up U8 on the dwg is really U10, and U10 on the dwg is really U8.

Ray,

The ocillator is something that I'll check, I bought both the big 4 pin one and the smaller SMD crystec. I installed the SMD but had difficulty, I might have screwed it up. I don't have a scope but I'll go over everything with a powerful magnifying glass and check for shorts, and try reflowing the clock. If I don't find any thing and it still won't work, I'll try swapping the clock out for the big one.

Thanks for all of your help and patience,

PJN

[6h5c]

Ok, that's a good point, at least then you'll know the clock should be working allright.

Ray

[PJN]

Does anybody have a pic of the completed underside of a working 1.5 board that they could post. I want to double check my installation.

Thanks

PJN

[mikel_ann]

Check post #148

regards Michael

[PJN]

Hi everyone,

I finally got some free time to try troubleshooting mu dac board some more. Unfortunately still no success but here is a run down on my findings so far.

- All the voltage regulators U8,9,10, and 11 are putting out the correct voltage, except that U10 and 11 are putting out +10.6v and -10.6v instead of 12v. but thats just a resistor change to correct.

- PCM 1794 : getting 3.3v on legs 2 & 9 as per diagram, getting 5v on 15,21,22,23 & 28 as per diagram.

- AD1899 : geting 3.3v on proper legs as per diagram.

- CS 8416 : getting 3.3v to legs as per diagram.

- U4 & 5 : getting +10.6v on leg 7 and `10.6 on leg 4 as per diagram.

- I carefully checked the board for shorts under magnification and didn't find any.

- After the above checks I removed the SMC clock and replaced it with the 4 pin canned clock.

Still won't sing. I don't have any equipment other than a DMM. Any suggestions on what I could/should check next would be greatly appreciated.

Thanks,

PJN

[6h5c]

A small suggestion: check if the RESET pins become high, +3.3V. If somehow things around U6 don't work correctly, the DAC remains in RESET state and there's no output either.

Ray