Question about HP iPAQ H4150 Pocket PC
Hello, one day two month ago my Ipaq H4155 work fine, and i put it in the morning in the cradle to charge it. An hour later i note that the device was turn off and i try to switch on but nothing happens. I try severals times and weeks after, with all the solutions posted in many forums: probe another battery, change the battery, charge the battery in the cradle, plug the device directly to the AC charger, hard and soft reset, go to flash mode, replace the screen, probe with other charger, etc., but nothing happens, no lights, no screen image, no nothing. I'm really frustated and really need help.
I had some similar experiences with these ipaq's when I was working in a specialised service center. I'll try to give some help or tips through the internet, altrough if i could have seen or diagnosticate these pda's myself it would have been more easier. First of all these problems have 2 main causes. Most of the pda's comply with one of them, it is very rare that a pda will develop this problem by having both causes.
The first cause is the hardware one. A component called the main voltage convertor is broken. It's a small chip that uses the voltage given by the main battery to convert it's value to various tensions required by some of the components on the pda's main board. If some sub-parts of this chip fails to work, the result will appear as the problem you face, In this case there isn't much to do. Most service centers will replace the whole mainboard because that particular chip is very hard to find as a replacement and difficult to desolder from the board.
The second cause could be a major firmware / ROM memory corruption. These things can happen out from nowhere. In my time working for service centers I've tried to isolate a pattern for this problem but without much succes. However it seems that most of these problem tend to appear durring charging cicles due to power spikes or drops on the main AC voltage supplied to the charger. This is only a supposition, I'm not sure yet on this cause. What to do here? Well this problems are fixable but first of all you must be sure that this is a software problem, not a hardware one. So let's diagnosticate some things.
Try to charge the pda. Ignore any lights or beeps or whatever your pda is showing on the screen. As long as the charger is connected the charging process is based on the most primary charging circuits on the pda's motherboard. If the pda is not charging or cannot hold any charge (when you unplug it the screen fades away or it simply doesn't do anything else) maybe that circuit is broken (this is a a sign of serious hardware problems ) or maybe the battery is to old/weak. Batteries don't die out of nowhere, if you remember your pda to work and have some 2-3 hours of standby time it's imposible that now, suddently the battery has drained out so much that even if charged it can't hold out at least 30 min.
So we will assume that you charged the pda for at least 2-3 hours and you see some sign that the battery is working. The next step is crucial. TRY TO PUT THE PDA IN BOOTLOADER MODE. You will achieve this by pressing (and keep them pressed!) the following buttons : power, the far left and right buttons near the control pad (joystick or whatever some people call it) and reset button. You may need another person to help you press these buttons. the order should be the following (first power, then the 2 keys, then reset button for as long as it takes to enter bootloader mode). YOU SHOULD SEE A WHITE SCREEN WITH THE HP LOGO.
If your pda fails to do that, there is nothing more you can do to restore it in a DIY fashion. Probably the bootloader is corrupted or you have a hardware fault. Only a specialised HP service center can help you now. In most cases this will end up with a motherboard replacement.
If your pda does that, then there is a chance to fix it. We will need to probe the bootloader for direct data acces. This is needed for having the ROM memory (and operating system) rewritten. A small program called Mtty will be required to access the bootloader via an usb link.
Please make this tests first and then reply with your results. If anyone of you is in situation #2 there may be a chance.
Posted on Feb 10, 2008
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