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I have been struggling with this Zune 80 AC charging issue all morning. I decided last night that the Zune must be looking for the new USB standard configuration for AC - USB chargers, but this morning I shorted & floated the data lines on a USB extension cable & it didn't work. My charger is a Belkin & supplies 550ma. That should be plenty as it meets the USB standard for computer devices. I'm baffled. I even suspected that Msft. had set it up so the Zune charger scheme was proprietary & not the USB standard. I don't know why I think such a thing about Msft! I will try the one listed above from Walmart &, if it works, I will try to see how it differs from my other one. Thanks for the info. BTW here's the info about USB changes: Sourced from EDN website.
"Both the new Chinese and USB-IF standards provide guidelines for detecting the power-source type by reading the impedance between D+ and D. More specifically, a compliant wall charger internally short-circuits D+ and D and leaves the shorted node floating. Therefore, D+ and D short together but do not connect to any part of the charger. The new Chinese standard doesnt specify short-circuit-detection mechanisms, whereas the USB-IF battery-charging specification 1.0 sets forth two alternative methods.
The USB protocol uses the D+ and D signal lines to form a differential pair. D+ and D carry binary data from an upstream port to downstream devices or from downstream devices to an upstream port. The USB 2.0 specification requires that 15-kΩ±5% resistors that connect to ground should terminate the D+ and D lines at host or hub ports. A simple circuit detects whether the upstream port is a charger that the new standards specify (Figure 3). If the upstream port is a wall charger, D+ and D should short together, and the shorted node should float."
Just in case you are in need, in a related issue, Buy.com has the Zune AV pack (works for Zune80s) for $19.99, plus $7 S&H. An amazing deal if you want to use your Zune with a home stereo. I have one in my office (paid $59 and I thought that was good). Now, $20.
OK, got it! Looking at the new USB-IF battery charging spec. 1.0 it looks like this.
Wall chargers should have the D+ & D- pins shorted together & floating.
PCs & some other devices should have the D+ & D- pins connected to gnd. through 15k resistors.
Well I tested the musicPower Dual Port charger from Walmart (works with Zune) & it shows about 15k to gnd. on the data lines, so apparently the Zune wants to be hooked up to a PC no matter what & can't detect a properly configured wall charger. There is something else in the circuit on that charger 'cause I seem to be charging a cap while measuring from the data pins to gnd.
I will try the one listed above from Walmart &, if it works, I will try to see how it differs from my other one. Thanks for the info. BTW here's the info about USB changes: Sourced from EDN website.
Linear Mode
