I used filter network before in my AN dac and it sounded bad. That's why AN bypassed it eventually. I hope that is not the problem with this board
A 330R resistor parallel with a 820pF cap at the output of the AD1865 used in the DAC broad of AN
I think the DAC ASH almost the same as the AN's DAC broad but have a better power supply, or you can install a 0.01uF cap parallel with the IV resistor to see if there any help...maybe the designer here know how to do
I think you helped me locate the problem. The 74H is not outputting the right voltage. I just got off a long very frustrating chat with Quanghao.
If there was an issue with the output the sound would be very different. I believe I have to get the 74H working then deal with the output I/V if they present an issue.
Yes, I ordered this board because it is a copy of the AN board but with better power.
What I need to know is this: If both chips blew up what caused them to blow up in this circuit? I have never blown one of these chips. I know both were working fine. When I put them into the board they both measure exactly the same - being off.
I could order more 74H chips but if the board is blowing them up OR if there is an issue with the PCB then there's no need to order more just to blow them up. Maybe something is shorting to ground in that area?
If there was an issue with the output the sound would be very different. I believe I have to get the 74H working then deal with the output I/V if they present an issue.
Yes, I ordered this board because it is a copy of the AN board but with better power.
What I need to know is this: If both chips blew up what caused them to blow up in this circuit? I have never blown one of these chips. I know both were working fine. When I put them into the board they both measure exactly the same - being off.
I could order more 74H chips but if the board is blowing them up OR if there is an issue with the PCB then there's no need to order more just to blow them up. Maybe something is shorting to ground in that area?
you can remove it?? you connect direct to DAC??
you measure: 74HC04
Pin 1=2.57V
Pin 2 = 2.57V
Pin 4= 5
Pin 6 = 5V
Pin 8,10, 12 = 5V
you measure: 74HC04
Pin 1=2.57V
Pin 2 = 2.57V
Pin 4= 5
Pin 6 = 5V
Pin 8,10, 12 = 5V
I did remove it once and got the same distortion
I just checked for shorts on the 74H pins. No shorts to ground.
Since the 74H data sheet shows what looks like internal diodes I measured the pins like diodes as shown and the chip measures how a diode would ie readings in only one direction.
So what are the potential areas that would pull down its voltage aside from short to ground which I don't measure?
I just checked for shorts on the 74H pins. No shorts to ground.
Since the 74H data sheet shows what looks like internal diodes I measured the pins like diodes as shown and the chip measures how a diode would ie readings in only one direction.
So what are the potential areas that would pull down its voltage aside from short to ground which I don't measure?
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Just for grins. Here's the Audio Note Dac board schematic (kit board not production board)
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Maybe some area or pinout of the 74HC04 shorted to GND. You can check the pin without the chip, and check it point to point to see is there any point being shorted to ground.
Hi,
it seems that the chips are not the reason, because you changed them all with no result.
Are you sure that all of the chips receive the 5V?
You should measure the voltage at the capacitors close to the chips.
If it is wrong there, the fault must be BEFORE the actual dac chips, either the salas shunt or the tl431 circuit.
I had a similar bug, because I soldered some wrong resistors (belonging to the tl431 circuit), so the chips had the wrong voltage, although the salas shunt was working properly.
When the tl431 has not enough voltage, it distorts btw.
I blew one ad1865, fortunately I had another one.
good luck, it is worth the trouble soundwise...
cheers,
Juergen
it seems that the chips are not the reason, because you changed them all with no result.
Are you sure that all of the chips receive the 5V?
You should measure the voltage at the capacitors close to the chips.
If it is wrong there, the fault must be BEFORE the actual dac chips, either the salas shunt or the tl431 circuit.
I had a similar bug, because I soldered some wrong resistors (belonging to the tl431 circuit), so the chips had the wrong voltage, although the salas shunt was working properly.
When the tl431 has not enough voltage, it distorts btw.
I blew one ad1865, fortunately I had another one.
good luck, it is worth the trouble soundwise...
cheers,
Juergen
I did a continuity check to ground on all the pins of 74H last night and there was no short there.
Just now I removed the 8414 then tested the 74H. Same result
Then I removed the 1865 - Same result
Then I swapped in and out the CS and 1865 and no result.
Does this chip have a closer relationship to the CS8414 or the AD1865?
I get fine voltage on the V-in of this chip just not on all the v-out
Just now I removed the 8414 then tested the 74H. Same result
Then I removed the 1865 - Same result
Then I swapped in and out the CS and 1865 and no result.
Does this chip have a closer relationship to the CS8414 or the AD1865?
I get fine voltage on the V-in of this chip just not on all the v-out
Some progress.
I built a small rig and put one of the 74H chips in it and fed the chip voltage. In the rig all the pins that should have voltage do. IE they all have the proper 5V.
If I power the chip only in the board I do not get those voltages. This proves the chips are ok.
I built a small rig and put one of the 74H chips in it and fed the chip voltage. In the rig all the pins that should have voltage do. IE they all have the proper 5V.
If I power the chip only in the board I do not get those voltages. This proves the chips are ok.
I completely give up. I'm happy for others who were able to make this board work but I cannot.
I looked at every single trace and touched up every single solder joint. There is no change at all when the chips are in the board. None.
I suspect a problem with the PCB but I have no clue. Its no frustrating and defeating. 🙁
I looked at every single trace and touched up every single solder joint. There is no change at all when the chips are in the board. None.
I suspect a problem with the PCB but I have no clue. Its no frustrating and defeating. 🙁
I not Know, what i can help you now??
only say, please sent to me, i can fix it to you!
I no known where it is wrong in the PCB??
there are many member was successful with PCB!
Maybe I got the bad one of the bunch. I'll hope someone in the U.S. can help but if they can't I'll just put the old board back in and maybe send it to you.
Hello Well i have sorted the heater volts out 6.3 and hv +300.
On the other board the rails are + 5v -5V that was the easy part .
All the 5v points around the chips are ok except pin 12 on 1865 it reads 2.5 v traced it back to pin 12 on 8414 it reads the same ?
i noticed that the led l19 did not come on .
am taking apart to check for bad joints .
cheers john
On the other board the rails are + 5v -5V that was the easy part .
All the 5v points around the chips are ok except pin 12 on 1865 it reads 2.5 v traced it back to pin 12 on 8414 it reads the same ?
i noticed that the led l19 did not come on .
am taking apart to check for bad joints .
cheers john
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