Don't PC motherboards have multiple grounded mounting holes?
Single-point grounding would be an EMI nightmare.
When in doubt, ground it out.
-- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
I was discounting audiophoolery. Infinitesimal market.
I know what it is. Never looked inside.
Do you trust the specs? Do you really care?
I took no offense but as long as you were going there...
They shouldn't. That's the point.
No, their purpose is *not* to "impart a sound". That's why they're used. Isolation - yes. Balancing - yes. Altering the sound? Nope. If you want that, use toobz. ;-)
Well, for certain values of "it", I suppose.
We have a slogan similar to that at work..
"When in doubt, ship it out" Then, for the longest time there was a banner hanging in the shipping area, quote "The customer is the next inspector", someone got smart and decided to add a little at the beginning for all to see, "Don't worry, The customer is the next inspector", that actually was up there for a while before those that mattered noticed it. That area of the operation has a lot of QC testing taking place just prior to package the product for shipment.
I am sure you have QC check points very close to the shipping process, too.
Jamie
Funny. When we have any doubt about something, we don't ship.
-- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Agreed. Getting it back is always far more expensive than fixing it in the first place.
I guess you did not understand correctly. There was no wall wart. DO-160 testing is for aviation, you would not want to use something like this in aircraft. The case ground and signal ground where connected. The power for the USB device came from the same source as for the USB host. There where also no performance problems. The problem was radiated emission which was way above limits when the shield was not connected at both sides to the case. With connection at both sides the emission was bare measurable.
-- Reinhardt
Halftrue, not nonsense. It's common practice to connect the left channel shield to chassis ground, and leave the right channel shield floating. It's easy to see this, on a turntable, because this connection is made at the phono cartridge.
** Even worse, irrelevant nonsense.
FYI:
Phono pickups are *floating* sources - so cable shields can only possibly be grounded at the amplifier end.
Merely plugging the RCA leads in does this and that is mighty hard to avoid.
Leaving off one of the ground connections to the two coils in the PU normally means loss of signal from that channel.
.... Phil
...
Nor is it avoided. I never said the shield was unconnected at BOTH ends. Only that the right channel shield does not connect to any chassis or shield inside the phonograph.
Not leaving off the ground connection to the coil. Only, not connecting the second (in this case right channel ground) cable shield to chassis or shield of the phonograph. Of COURSE you connect it to the phono cartridge right ground pin, but NOT to the phono cartridge case (which is grounded through the left channel ground).
** But YOU said it was - wanker.
** That is exactly what YOU posted:
" ... and leave the right channel shield floating ".
BTW: Better learn what the word "floating" means sometime.
** What a load of incomprehensible bollocks that could have been stated in one short sentence:" The metal case of a phono PU is generally connected to one RCA lead shield."
The other common way is that it connects to an all metal tone arm that has its own ground wire.
NONE of which is even on-topic.
... Phil
to
the maximum current in one phase. Max voltage drops along cables can be computed from this.
neutral/ground
so has no voltage drops.
BNC-BNC
cable?
the AC supply wiring.
Once again Phil Allison gets outside his demesnes and speaks incorrectly again. Phase imbalances are really quite frequent and the reason that neutral conductors are the same size as phase conductors today in the NEC and related standards and regulations.
?-)
The problem was, they first connected the USB device to the ungrounded power supply. Since there was no connection to ground the capacitively coupled AC was on the signal ground. When thy connected the device (with unconnected shield) to the PC these AC voltage hit the USB inputs and pfft.. The input impedance of the USB signal lines was to high to gt the coupled voltage down to acceptable levels. It happened only sometimes depending what pin got the connection first. When GND was first it shorted the AC to ground and nothing happened.
This does not have much to do with USB itself. It is a common problem that any ungrounded AC powered supply creates. I had the same effect with a HP printer in the days of centronics printer connectors. The printer had an external PSU without a PE pin in its mains plug. Fortunately I first touched the connector shield at the PC printer port with the cable connector and saw the sparks.
The USB connector is designed in a way that normally the connector frame (shield) first touches. This protects from stray voltages as well as ESD _iff_ the shield is connected on both sides of the cable.
-- Reinhardt
And give the full difference in ground potential onto your signal lines. They like it if they are sometimes fed it bit more voltage than usual :-)
-- Reinhardt
USB is bi-directional. So which side is the input?
-- Reinhardt
That would be "customer-oriented testing" :-)
In many cases, this has been the standard method in software industry since mainframes OSs.
It seems that some Chinese manufacturer are satisfied with 95 % yield.
If the customer complains about a defective unit, just send a new device (hoping that the replacement unit is not defective), without even asking the customer to return the defective unit.
Long time since I did anything that needed any knowledge in this area, but what Phil is saying seems to be about right - at least in OZ.
I recall a manager attempting to instill a sense of duty in us by explaining how a Sony TV is turned on for the first time by the customer. Their defect rate is so low that they can do this it would seem.
-- Rick
Try to test it in the near field of a 50 KW AM radio transmitter.
You have a lot to learn, child.
-- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.
Read what I replied to. AUDIO. Not USB.
-- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge.
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