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> I Broke The Charging System On My C3000, not by overvoltage or reverse polarity
post Feb 15 2008, 01:12 AM
Post #1

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Joined: 28-January 08
From: Arizona
Member No.: 21,290

Hi all

Well, my Z doesn't charge it's battery anymore. sad.gif It's my fault; I was experimenting with an alternative power source for the Z (a USB hub powered by a nice bicycle generator) and failed to exercise the sort of caution that something as beautiful (and pricey) as a c3000 deserves.

I compared my experimental power source with the power adapter that came with my USB hub using a volt meter. I am certain that I got the polarity and voltage correct. The rest is speculation on my part, I am not an EE and I was experimenting way outside my expertise as a programmer and a cyclist. rolleyes.gif

I hooked up the alternator's output (the frequency of this AC varies with the speed of the bicycle wheel and goes very low, maybe 10hz) to a bridge rectifier. This rectified DCish voltage I fed into a switching DC-DC converter (DE-SW050) which outputs 5v and can take up to 30v input. That 5v is powering a USB hub. The DE-SW050 has two capacitors built in, but I guess they are too small to smooth out the ripples when the frequency is low (the datasheet claimed 2% ripple which shouldn't hurt anything). The blue LED in the USB hub flickers visibly, which should have given me pause for thought. I guess I didn't think carefully about what rippling voltage might do to something expecting smooth DC.

I observed that this setup charged my least expensive USB device (an iPod nano) successfully. Here's where I acted hastily out of excitement: I plugged in the Z and went for a ride. After that, the Z does not seem to charge batteries. The charge light comes on, but I left a dead one in there over night and the Z didn't turn on in the morning. That was stupid. Oh well, live and learn. At least the Z still works. mellow.gif

Anyway, two questions:

First, I've read somewhere on this forum that there is such a thing as an external BL-08 charger but haven't been able to find one. Anyone know where I can get one in the USA?

Second, does anyone have any idea which part I might have damaged (possibly a regulator that I cooked with too much current) or where it is on the board? Or any thoughts at all from an EE? I'm pretty much stumped and I'll probably just have to settle for charging batteries externally.

I opened the Z up and looked around, particularly near the power-related stuff. I couldn't see any evidence of damage.

This forum has been very helpful. Thanks, everyone!
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post Mar 6 2008, 09:26 AM
Post #2

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Posts: 135
Joined: 27-June 05
From: Prague, Czech Republic, Europe
Member No.: 7,468

New Zaurus models have high value fuses.

There is a low risk of any damage from the external power source input - nothing except and charging/power circuit are connected directly to 5V.

Datasheet of the chip: http://www.penguin.cz/~utx/zaurus/datashee...rging/sc801.pdf

I see the annoying charging bug in 2.6.24, too. It nearly never charges (or at least indicate charging) when I plug power supply. I have to unplug and plug again. Then it works.
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