jpbeale wrote:
> My MZ-RH1 works and charges fine with the Sony supplied AC adaptor
> AC-S508U. However, it does NOT work with a $20 USB battery pack ...
> This pack has a green LED which comes on, and I checked with a
> voltmeter and it is providing +5.25 V which seems OK and I believe
> within the USB spec. The pack spins up an external USB laptop hard
> drive, but the RH1 pretends it isn't there at all.
>
> I would not rely on reports about earlier HiMD units that had a
> coaxial-type external power jack (not just USB power). I suspect those
> may be more forgiving of power supply types.
This is an AC adaptor that feeds the unit through the mini-USB connector
I belive. Note that USB spec says that device (the MZ-RH1) can only
pull 100 mA until it has negotiated with the USB host for up to 500 mA
power from the USB bus.
When the USB port is used for a charger it is going outside of the USB
spec. The AC adaptor spec:
http://servicesales.sel.sony.com/web/viewItemDetail.do?operation=getItemDetail&itemID=605954&category=5&categoryName=Portable%20Audio
says that it provides 800 mA of current. Some device manufactures use
the 5th ID pin of the USB jack (actually On-the-Go extension to USB)
to tell the device that something other than an ordinary USB data
cable is connected. The device can then recognize a compatible
charge and enable the on-board charge, while disabling the charger
for ordinary data connections and also "dumb" power like a USB
battery pack.
If you're into DIY'ing a battery pack, it probably takes a single
resistor from the ID pin to either B+ or ground to identify as a
charger. You need to see what the Sony AC adaptor does with the ID pin.
-- Mike
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