I have a PCM2902 that is using it's own power supply...nicely built on a PCB...works great except that if a glitch is imposed on the power line through something healthy like a refrigerator or a flourescent fixture on/off, it will disable.
If I go to device manager, I won't see "USB audio device" and the USB composite will show an exclamation mark of not installed.
If I reboot.....everything is fine until another AC glitch.... and it happens again.
I have the power supply filtered well on the LM317 input and output but still having problems.
Both jet audio and media player have been used.
Has this been a problem for anyone else?
If I go to device manager, I won't see "USB audio device" and the USB composite will show an exclamation mark of not installed.
If I reboot.....everything is fine until another AC glitch.... and it happens again.
I have the power supply filtered well on the LM317 input and output but still having problems.
Both jet audio and media player have been used.
Has this been a problem for anyone else?
Does it the same when the audio is not connected, i.e. the USB cable is the only one connected? Try disconnecting the cables to find out which one is the interference source. For power, try using USB-power or just ordinary battery.
Problem is most likely common mode interference, it still remains regardless how much conventional (differential mode) filtering you apply.
Regards,
Janne
Problem is most likely common mode interference, it still remains regardless how much conventional (differential mode) filtering you apply.
Regards,
Janne
just a guess: the problem may be the computer's power supply dropping out at that point. Power on the USB bus is required to sense the devices on the built-in ports
try the computer on a big UPS - not a bad thing to get anyway. There are tons of cheap units on ebay that'll do the job for these brownout moments
Peter
try the computer on a big UPS - not a bad thing to get anyway. There are tons of cheap units on ebay that'll do the job for these brownout moments
Peter
Also....
It only has this problem with the PCM2902 interface.
If I switch back to my sound card, it won't react to a glitch.
Sometimes I have to reboot, but lately, if I turn on/off the flourescent fixture (which is on the same circuit)....it will just stop the song.
I can hit play again and it will function but it always takes the windows volume control down about 50%.
It will do this wih both Jet audio and media player.
I'm going to try some more noise suppresion but sure would like some clues on this.
Thanks.
It only has this problem with the PCM2902 interface.
If I switch back to my sound card, it won't react to a glitch.
Sometimes I have to reboot, but lately, if I turn on/off the flourescent fixture (which is on the same circuit)....it will just stop the song.
I can hit play again and it will function but it always takes the windows volume control down about 50%.
It will do this wih both Jet audio and media player.
I'm going to try some more noise suppresion but sure would like some clues on this.
Thanks.
Like I said, try to determine the coupling path of the interference (which disrupts USB-line communications). Does unplugging of the audio output cable (i.e. disconnecting the output cable and then playing music and experimenting with the light switch) entirely have any effect?
If you experiment with the filter, I suggest that you'll add some common mode filtering, unlikely the differential mode interference is the problem.
Regards,
Janne
If you experiment with the filter, I suggest that you'll add some common mode filtering, unlikely the differential mode interference is the problem.
Regards,
Janne
just a guess -- the Codec demands 50 to 60 ma -- if you are using a 1,000uF storage cap on the LM317 it will discharge to less than 3.3V (from 5.0V) in 30 milliseconds or so --
i can knock out the device manager for my data-acquisition cards if i overload the current -- won't recognize the device until a hard reboot.
i can knock out the device manager for my data-acquisition cards if i overload the current -- won't recognize the device until a hard reboot.
I'll be damn....if I disconnect the RCA's from the board it won't do it.
I have an AD823 opamp on the output of the PCM2902.
Now that I look at this board closer, I forgot to add some filtering components I had made room for on the board....a 470pf across the output and a 100k for impedance setting.
OOPS.....maybe that will clear it up....I'll let you know.
I have an AD823 opamp on the output of the PCM2902.
Now that I look at this board closer, I forgot to add some filtering components I had made room for on the board....a 470pf across the output and a 100k for impedance setting.
OOPS.....maybe that will clear it up....I'll let you know.
Well....no change, but definetly it's getting back to the computer through the receiver RCA jacks.
I have 470pf caps across each output but no change....also added the 10 ohm resistor between digital and analog grounds (which I had left out).
No hum at all in the thing....dead quiet....did have a ground loop that I cured initially.
Still acting up though...in fact now, not only will it stop the song when I hit the light switch but it will start it again if I turn it back on.
???
I have 470pf caps across each output but no change....also added the 10 ohm resistor between digital and analog grounds (which I had left out).
No hum at all in the thing....dead quiet....did have a ground loop that I cured initially.
Still acting up though...in fact now, not only will it stop the song when I hit the light switch but it will start it again if I turn it back on.
???
Jacjinnj....
I don't have a problem unless these RCA cables are connected to the amplifier.
So that eliminates any power supply problem.
I think somehow the data (D- and D+) is being corrupted by the induced noise....what is wierd is that it that the audio will actually turn on again if I play with the light switch enough.
How can any of this be a power supply problem?
Would a flourescent switch actually cause line voltage sag?
Perhaps there is a grounding design flaw on the PCB but I sure don't "hear it".
I don't have a problem unless these RCA cables are connected to the amplifier.
So that eliminates any power supply problem.
I think somehow the data (D- and D+) is being corrupted by the induced noise....what is wierd is that it that the audio will actually turn on again if I play with the light switch enough.
How can any of this be a power supply problem?
Would a flourescent switch actually cause line voltage sag?
Perhaps there is a grounding design flaw on the PCB but I sure don't "hear it".
Is your amplifier powered by another powerline branch circuit? Is it connected to ground there? Maybe there is a small capacitor between the amp's ground and one of its powerline wires. I suspect that there are transient voltage differences between the powerlines feeding the amp and the computer and USB device. Maybe heavy copper braid or wire tying the two systems' grounds together will reduce the transients that are distrupting operation. The heavy wire would reduce the transient voltage differences between the two systems, hopefully below the threshold of interference.
That suggests that problem is common mode transient.
Also, tie all grounds together as tight as you possible can. Have you connected the USB-cable shield to your device's ground? If not, then do. At least capacitively. Problem is that your device and the computer bounce to different ground potential (via usb-cable common mode inductance) momentarily when the transient occurs.
Separate grounds, although good for audio frequencies, can be real PITA when it comes to EMI. EMI transients have high bandwidth, ESD transients can be as high as gigahertz range.
Perhaps one of the most difficult aspects in digital design is transient immunity. Often, EMI immunity test failures occur during EFT or ESD tests. No big deal in analog signal, it just produces small "click", but in digital it can crash the whole system. So much for touted digital robustness against interference.
Perhaps a hybrid ground, i.e. connecting all grounds together capacitively and/or using common-mode choke on the usb and audio outputs, will cure the effect.
Regards,
Janne
Also, tie all grounds together as tight as you possible can. Have you connected the USB-cable shield to your device's ground? If not, then do. At least capacitively. Problem is that your device and the computer bounce to different ground potential (via usb-cable common mode inductance) momentarily when the transient occurs.
Separate grounds, although good for audio frequencies, can be real PITA when it comes to EMI. EMI transients have high bandwidth, ESD transients can be as high as gigahertz range.
Perhaps one of the most difficult aspects in digital design is transient immunity. Often, EMI immunity test failures occur during EFT or ESD tests. No big deal in analog signal, it just produces small "click", but in digital it can crash the whole system. So much for touted digital robustness against interference.
Perhaps a hybrid ground, i.e. connecting all grounds together capacitively and/or using common-mode choke on the usb and audio outputs, will cure the effect.
Regards,
Janne
Hi,
i had a similar problem with my diy usbdac built around the pcm2707.
The problem was this:
- usbdac stop to work when i turn off the pre or the ampli used with it and i have to reboot the pc to have it work again. When turning off the pre or the ampli, together with the problem of the usbdac, i hear click noise on the speaker (the two problem are correlated).
I solved the problem doing many action at the same time (bad practice - so i can't say which one was resolutive):
- i have put 220 nF X2 rated capacitor on the transformers primary of the pre and the ampli (no more click noise on turning off)
- i have connected the ground and the mains hearth with a 10 ohm 5 W R in parallel with 100 nF C in the pre and the ampli
- i have put a ferrite toroid in the usb cable near the usbdac (one turn of the usb cable in the toroid)
- i have put ferrite bead in the wire connecting analog ground to digital ground in the usbdac.
sorry for so long post with so bad english
ciao
andrea
i had a similar problem with my diy usbdac built around the pcm2707.
The problem was this:
- usbdac stop to work when i turn off the pre or the ampli used with it and i have to reboot the pc to have it work again. When turning off the pre or the ampli, together with the problem of the usbdac, i hear click noise on the speaker (the two problem are correlated).
I solved the problem doing many action at the same time (bad practice - so i can't say which one was resolutive):
- i have put 220 nF X2 rated capacitor on the transformers primary of the pre and the ampli (no more click noise on turning off)
- i have connected the ground and the mains hearth with a 10 ohm 5 W R in parallel with 100 nF C in the pre and the ampli
- i have put a ferrite toroid in the usb cable near the usbdac (one turn of the usb cable in the toroid)
- i have put ferrite bead in the wire connecting analog ground to digital ground in the usbdac.
sorry for so long post with so bad english
ciao
andrea
Well my grounding scheme (120v) back here in the shop isn't the greatest but I even had the problem in another room which was all up to code.
Everytime I opened up the refrigerator door, it would stop the media player/PCM2902 interface on the computer.
Considering the fact that most home installations of the unit "wouldn't" have "ideal" grouinding schemes etc.....then it's a dissapointment to see my USB audio system be so sensitive to this noise.
At least I see one response from someone with a similar problem on a PCM2702 and I'll try all the suggestions....I do have a ferrite bead on the USB ground line.
I wonder what EXACTLY is happening though.....like I say, when I connect the RCA output jacks to the stereo amplifier....that is when I have the problem.
So, the noise is being generated on the amp ground circuit and interfering with the USB data?....thus stopping media player on the computer?
Well anyway....the easy fix would be to replace the damn bulb in the flourescent fixture.....it's been hard to turn on for the past 6 years!!
....and it clicks and pops through the whole house.
My problem is, I can build a project that works fine....but if I find one thing that is a problem, I like to build for absolute worst case scenario.
(It's a bad habit).
I pulled the bulb out this morning but in a way...I hope it doesn't fix it.
That's too easy.
Everytime I opened up the refrigerator door, it would stop the media player/PCM2902 interface on the computer.
Considering the fact that most home installations of the unit "wouldn't" have "ideal" grouinding schemes etc.....then it's a dissapointment to see my USB audio system be so sensitive to this noise.
At least I see one response from someone with a similar problem on a PCM2702 and I'll try all the suggestions....I do have a ferrite bead on the USB ground line.
I wonder what EXACTLY is happening though.....like I say, when I connect the RCA output jacks to the stereo amplifier....that is when I have the problem.
So, the noise is being generated on the amp ground circuit and interfering with the USB data?....thus stopping media player on the computer?
Well anyway....the easy fix would be to replace the damn bulb in the flourescent fixture.....it's been hard to turn on for the past 6 years!!
....and it clicks and pops through the whole house.
My problem is, I can build a project that works fine....but if I find one thing that is a problem, I like to build for absolute worst case scenario.
(It's a bad habit).
I pulled the bulb out this morning but in a way...I hope it doesn't fix it.
That's too easy.
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