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> I Broke The Charging System On My C3000, not by overvoltage or reverse polarity
Blake
post Feb 15 2008, 01:12 AM
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Posts: 9
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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Blake
post Feb 15 2008, 04:01 AM
Post #2





Group: Members
Posts: 9
Joined: 28-January 08
From: Arizona
Member No.: 21,290



IT'S ALIVE! ohmy.gif

I was wrong! It does still charge batteries. This is really hard for me to explain because there were too many variables.

I definitely did something to my Z that it didn't really like. At one point I was watching the GPE battery monitor while connecting and disconnecting the power. When I connected it, the charge indicator would rise a bit, but it never said the AC was connected.

At one point the charge light would not come on at all. Since it did this right after my experimental ride, I took it as a grave sign that I had borked it good. However, in RETROVISION (which is a bit like retrospect but with a 1950s feel) it was probably just lack of contact with my cheap imitation battery, because after I opened the Z up and closed it again, the charge light came on (coincidence). However, the Z still wouldn't turn on, even after leaving it charging for more than an hour. I can't explain that. Even a totally dead battery gets enough charge to boot the Z after 15 seconds, no? I don't mean one straight from the factory, I mean one that you just drained with the Z.

Thoroughly downhearted, I started searching for an external battery charger. Then I went to heat up some soup. When I came back, the Z was ON and displaying the login screen. Battery charge indicator said it was charging and at 50%. I hadn't even pressed the ON switch (for at least 10 minutes). I cannot explain that, but that is what happened.

What I learned from this ordeal:

1) Undervoltage and rippling voltage do not seem to damage the Zaurus in any serious way, though it did produce some results which confuse me
2) When pretending to be an EE, it's probably a good idea to consult a real one and to be more patient than I was
3) When in doubt, go heat up some soup and come back in a bit and everything will be fine (YMMV on that)

I'm so happy! Not only is my Z undamaged, but my bike-powered USB hub works, and just needs some smoothing capacitors or something to work with the Z. Tuesday I'm leaving for a long bike tour in Europe. With some luck I will have this working properly before then. The idea is to power my Zaurus, my iPod, a bluetooth GPS, and AAA rechargeable batteries with the bike. Huzzah!
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