Miro, I have the same issues as I had befor turning the C2 by 180°. The Dac was recognized once by the Laptop, but not a second time. I added the 4 10R resistors and mounted the AD1862 and a pair of opamps and wanted to enjoy music, but it did not work. The dac was not recognized, neither by the computer, nor by the usb bridge :-(
Now I have run out of ideas. Any idea from your side? Cheers, Ernst
Now I have run out of ideas. Any idea from your side? Cheers, Ernst
@ernesternest Problem can be in a cold joint or a solder bridge in PCM2706 chip. Try to resolder all legs, be sure to use a flux.
EEVblog #186 - Soldering Tutorial Part 3 - Surface Mount - YouTube
If you fail to solve it up, you can send it to me by mail and I'll fix it and send it back to your address
EEVblog #186 - Soldering Tutorial Part 3 - Surface Mount - YouTube
If you fail to solve it up, you can send it to me by mail and I'll fix it and send it back to your address
more issues
Good morning,
I could solve the not being recognized issue, after I have mounted firstly another (used) pcm2706 and later another new one. Good! So I again checked all the voltages and then mounted 2 DACs and 2 opamps. The DACs are from ebay and do look good (the really good ones from Paddy I keep for the main DAC). And then I became really frustrated, as I got no sound out of the headamp :-(. So I connected the DAC to my HPA and heard just a very low volume and very distorted artefakt of sound. At least. Hm. Never faced so many issues in my long solder career.
Miro, any idea? I am going to check, if I forgot anything or have still anything soldered in a wrong way (hpa chip is soldered in the right way).
The story goes on.
Have a good day
Good morning,
I could solve the not being recognized issue, after I have mounted firstly another (used) pcm2706 and later another new one. Good! So I again checked all the voltages and then mounted 2 DACs and 2 opamps. The DACs are from ebay and do look good (the really good ones from Paddy I keep for the main DAC). And then I became really frustrated, as I got no sound out of the headamp :-(. So I connected the DAC to my HPA and heard just a very low volume and very distorted artefakt of sound. At least. Hm. Never faced so many issues in my long solder career.
Miro, any idea? I am going to check, if I forgot anything or have still anything soldered in a wrong way (hpa chip is soldered in the right way).
The story goes on.
Have a good day
@ernesternest
It's a quite complicated DAC, although simple in its form. I'm sure you'll find a solution.
Check all polarized capacitors.
Did you use 74HCT164D shift registers? (because there is also 74HC164D which is CMOS and thus not working with this DAC). Volume and distortion may be related to this.
The AD1862 from ebay should be fine, although I've seen cases where the leg in the case was broken and causing problems (only one channel, the second channel worked). Your case is probably related to both channels, focus attention to the shift registers. I am sure it will work
It's a quite complicated DAC, although simple in its form. I'm sure you'll find a solution.
Check all polarized capacitors.
Did you use 74HCT164D shift registers? (because there is also 74HC164D which is CMOS and thus not working with this DAC). Volume and distortion may be related to this.
The AD1862 from ebay should be fine, although I've seen cases where the leg in the case was broken and causing problems (only one channel, the second channel worked). Your case is probably related to both channels, focus attention to the shift registers. I am sure it will work
Hi @ernesternest, after checking the pins, 74HCT could be killed with incorrect rotation (GND with VCC is reversed). Do you have a digital analyzer to check digital data on the LRCK, BCK, DATA, DL and DR pins while the music/sine is ON?
Be sure to use single opamps (not dual version), like LM6171, or any other single type.
Be sure to use single opamps (not dual version), like LM6171, or any other single type.
Interesting issue ... a cheap logic digital usb analyzer from ebay could be handy, it cost 8USD.
Assume:
- all voltages are ok
- PCM2706 is recognized
- logic circuits 74HCT correctly installed
- opamps in I/V inserted/rotated correctly
- R9, R10 have the correct value (from 1k up to 2k5, default 1k4)
- DAC chips are in a working condition and installed correctly
Then there has to be nothing, why it shouldn't work.
Measure all SMD capacitors for a short circuit, check the capacity of tantalum capacitors (replace the one that was rotated incorrectly).
Send a few detailed photos if possible, to see component labels
Assume:
- all voltages are ok
- PCM2706 is recognized
- logic circuits 74HCT correctly installed
- opamps in I/V inserted/rotated correctly
- R9, R10 have the correct value (from 1k up to 2k5, default 1k4)
- DAC chips are in a working condition and installed correctly
Then there has to be nothing, why it shouldn't work.
Measure all SMD capacitors for a short circuit, check the capacity of tantalum capacitors (replace the one that was rotated incorrectly).
Send a few detailed photos if possible, to see component labels
btw, I already made the error with brown tantalum smd package, the thick black mark is the +... not like an electrolytic.
If the pcb board was printed ans sent raw free of parts, one may also assume to an print error... while they have AI looking at error when you send all the files ! Resist the temptation to try with the genuine Rochester chips...
leave your head from the pcb one week to do something else then re check it rested with a magnyfing glass and your voltmeter. You are certainly now too much focused to find imho.
If the pcb board was printed ans sent raw free of parts, one may also assume to an print error... while they have AI looking at error when you send all the files ! Resist the temptation to try with the genuine Rochester chips...
leave your head from the pcb one week to do something else then re check it rested with a magnyfing glass and your voltmeter. You are certainly now too much focused to find imho.