Problem With Batteries?
Posted 05 March 2010 - 11:13 PM
Now there is a problem; the screen remains "dead"; I mounted new batteries; no change. Pressed P (reset): no change
I connected the USB cable: ALIVE!
However: With the USB cable, but without the batteries: DEAD.
So somehow the CP300 suddenly needs both powersources.
Did I (accidentilly) toggle an option somewhere? Or is there a hidden key combination that I should press?
Thank you for all tips and advice,
Posted 06 March 2010 - 03:58 AM
Posted 06 March 2010 - 03:54 PM
Only when both the batteries AND the USB cable are atached, the unit would come alive.
Not good enough. Strange, I could not find any clues on the internet, or on this forum.
So,...I openened the ClassPad (easy, 6 screws), and removed the cover (als very easy)
It is easy to trace the battery connection. +6V goes to a regulator IC210. It delivers a steady 4V.(I attached an external PowerSupply). It is smoothed (small capacitor) and directed to a double(?) diode D203. But somehow this 4V does not reach the unit.
When the USB cable is attached, 4V is also available on this diode D203 (other pin).
On the PCB, there is also a large capacitor. ONLY the 4V of the USB cable would feed this capacitor. Aha.
Likely cause of the problem: loose connection of the diode on the PCB.
Solution: resoldered the connections > fixed; the unit works fine again on batteries only too.
See attached a closeup of the connections that I resoldered.
Edited by Bas, 06 March 2010 - 08:25 PM.
Posted 06 March 2010 - 10:30 PM
Posted 07 March 2010 - 09:02 PM
P204-P203 on the left
P202-P201 on the right (text P202 cannot be read on the picture unfortunately)
Both sets of contacts (?) can be seen from the outside. Look underneath the batteries.
I guess that it can be used to activate/read something from the outside, without having to open the unit.
Does anyone have an idea?
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