Messages

1

General Discussion / New HOW-TO=Fixing Non-Charging CX00 Battery

« on: July 27, 2004, 07:01:31 am »

How did you know what the end voltage should be for this particular battery?

I just checked the battery voltage with a multimeter intermittently whilst it was charging, and was planning to stop a bit over 3.7v.  When I checked it at 4.2v, I said, "Shit, I'd better stop charging now, so the battery doesn't get too overcharged and risk damaging the Z circuitry".

-- Aussie

2

General Discussion / New HOW-TO=Fixing Non-Charging CX00 Battery

« on: July 27, 2004, 06:24:10 am »

i dont have external charger for zaurus battery

Nor do I, but I just rigged something up - a wire running from the positive inside pin of the charger to the positive terminal of the battery, and a wire clipped to the negative outside of the charger to the negative terminal of the battery.

-- Aussie

3

General Discussion / Battery or recharge circuit problem - C860

« on: July 26, 2004, 07:24:35 am »

Will do, but it will be in a few days (next weekend) when I have a multimeter again.  

What I will do is:

1) charge the battery outside the Zaurus - the multimeter shows that the battery charges to 4.2v quite quickly with my 5.1v, 2.5amp AC>DC charger. Then put the battery in the Z and check the service menu battery voltage adjust readings.

2) run the battery down, and recharge it in the Z until it is fully recharged. Then check the multimeter voltage of this fully charged battery, and the service menu battery voltage adjust readings.

Perhaps others might like to do the above also - all you need is a simple multimeter with positive/negative probes.

-- Aussie

4

General Discussion / Battery or recharge circuit problem - C860

« on: July 26, 2004, 06:52:55 am »

I'm pretty sure you can run the C machines without a battery in them - just plugged into the external supply

No, I just tried to run my C860 from the external supply (AC/DC charger) without the battery in, but it wouldn't run.  Put the battery back in, and it runs.

The only thing that I can run without the battery is the service menu.

Cheers from down under,

-- Aussie

5

General Discussion / Battery or recharge circuit problem - C860

« on: July 25, 2004, 07:05:12 am »

Success !!! .... one Z C860 unbricked :-)))

Everything in my previous post seems true, and is explained in more detail below ...  

1) THE BATTERY & CHARGER CIRCUITRY:
The Zaurus has a system to protect its circuitry, which can only be powered directly from the battery (with the excpetion of the service menu).  The AC/DC charger charges the battery, and the battery powers the Zaurus circuitry.

There is a voltage level flashed in memory - this should be 4.2v = a fully charged battery. When the battery is fully charged (=4.2v) the AC/DC charger cannot send current through to the battery (preventing overcharging and damage to the circuitry). When the battery voltage drains below this, the AC/DC charger can then recharge the battery, and the LED light will be on continuously. When the battery has charged, then no further current can flow through to the battery, and the LED blinks intermittently.

2) THE PROBLEM:
The problem that arises is that the voltage level which is flashed in memory becomes erased - I have not explored the reasons for this, but it happens. With this erased, then current cannot flow from the charger to the battery, and the battery drains such that the Zaurus won't boot (= bricked). Put in a new battery, and the Zaurus works again for a few hours until this new battery has drained.

3) THE FIX:
Now, there is only one way to flash a new voltage level to memory - via the service menu, which is accessed by holding down the D+M keys whilst pluging in the AC/DC charger. Here on page 2, option 6, is the Battery Voltage Adjustment. The Main Bat AD: is the present voltage of the battery.  Flash data: - -  is the voltage level stored in the Zaurus memory.  You can flash the present voltage of the battery into memory by pressing the [Home] or key.  But this will only flash the present battery voltage level, and there is no way of changing this. And if the present battery voltage has drained, then there is not much use in flashing a low voltage into memory - you need to flash a working voltage (preferably 4.2v).

What I did was simply charge my battery outside the my Zaurus by just connecting a wire from the positive centre of the charger to the positive battery terminal, and from the negative outside of the charger to the negative battery terminal. I then monitored the battery voltage level as it charged using a multimeter, and stopped charging once the battery voltage was 4.2v (it charged from 2.4v to 4.2v in about 2 hours).

Then, the fully charged battery was replaced in the Zaurus, and this voltage was then flashed to the memory.  

Success ... Zaurus unbricked, and all working perfectly.

I hope this HOW TO can be useful to others with the same problem of the battery not charging, and who suspect that the battery is a dud or the Zaurus circuitry is faulty.  

Best wishes from Down Under.

-- Aussie

6

General Discussion / Battery or recharge circuit problem - C860

« on: July 24, 2004, 09:39:39 pm »

Thanks Miami Bob.  Those links were helpful, but they still do not spell out a solution.  What I think is happening is ...

There is a battery voltage level kept in memory which is the voltage up to which the charger will charge the Zaurus battery.  This should be about 4.2V (the maximum voltage up to which the battery is charged).  

It seems that certain actions can erase this voltage from memory, which prevents the battery from charging through the Zaurus circuitry.  

The way to rewrite a voltage to memory is through the service menu, battery voltage adjustment - but this will only flash the memory with the voltage that the battery has at that time.  If the battery is fully charged, then the memory will be flashed with a voltage that will allow the Zaurus to boot up and run, and the charger will thereafter recharge the battery back up to this level. But if the battery has drained, then any reflashing will only allow recharging back up to this lower level ... In my case, my battery drained down to 2.4v, and so I can only reflash the memory with 2.4v, which is insufficient to boot my Zaurus.

Solution (I hope):

1) Get a new fully charged battery, and do a battery voltage adjustment/reflashing which would then allow recharging to this level.

2) Somehow recharge your existing battery outside the Zaurus (which will require a little creative ingenuity).  Then replace the externally recharged battery into the Zaurus and do a battery voltage adjustment.  

3) As a variation on 2), you can put your battery in the fridge to gain a small recharge.  Then replace it into the Zaurus, do a battery voltage adjustment, and then recharge the battery in the Zaurus to this new higher level. Repeat until the battery voltage adjustment is 4.2v.  

I will give 3) a try first, and report back.

Aussie

7

General Discussion / Battery or recharge circuit problem - C860

« on: July 24, 2004, 07:44:48 pm »

You might want to try booting with D+M, go to page 2, line 10, Charge, Enter & "left arrow" charging ON (use the "<- BS" key to get back out to the menu).

Thanks - I did this overnight, but the battery still didn't recharge :-((

I have 2 battery chargers - both working normally with the multimeter showing outputs of 5v (positive inside, negative outside).

I also did a NAND flash restore, which didn't help.  

What is the "Batt Voltage Adjust"  (service menu, page 2, line 6) ?

Aussie

8

General Discussion / Battery or recharge circuit problem - C860

« on: July 24, 2004, 07:01:08 pm »

What happens if you remove the battery for a bit (10sec - make sure no external power is supplied too) then try starting up (button on the back) - you may have to hold it for a little while.

Still dead as a dodo - black screen. The battery is drained down to 2.4V and the Zaurus won't boot up at this low voltage. All I can get is the service menu using the D+M+plug in AC/DC charger sequence.  And the battery will not recharge at all whilst in the Zaurus.

I was thinking of trying:
1) charging the battery outside the Zaurus directly from the charger;  
2) rigging up an alternative power supply directly to the Zaurus to see if it powers up normally (I know I have to be careful to use the exact specs); and/or  
3) borrowing another battery - this is no doubt the safest, but will take a few days.

? comments.

Aussie

9

General Discussion / Battery or recharge circuit problem - C860

« on: July 24, 2004, 09:42:38 am »

My Sharp Zaurus C860 arrived during the week, and pdaXrom was installed as per:   http://www.pdaxrom.org/index.php?showid=2&menuid=1

When I rebooted, the Linux operating system was eye candy at its best, and after a bit of a hack around, the system was shutdown by the command "halt".  

A few hours later, I press the ON button and ... nothing but a black screen :-((  

After reading all web sites and forums, all that I can do is get into a service menu by holding down keys D+M whilst plugging in the AC/DC charger.  

Running through all the hardware checks on this service menu, everything seems to work OK except the battery status is LOW.  Multimeter confirms that the battery is now 2.4V, and well below its normal fully charged voltage of 3.7V. However, placing the Zaurus/battery on the charger for several hours just doesn't recharge the battery !  

Is the battery or the recharging circuit in the Zaurus faulty, or is there something else that I should be doing ?

Help appreciated.  

-- Aussie