Help, My phone won't boot

[Guest jasonmgeorge]

Saturday my phone lost reception so I decided to cycle the power. The power key wasn't working so I pulled the battery to power down. After reinserting the battery multiple times I had results varying between a boot hang to a missing SIM message. I tried with and without my SIM card, but could never get the phone to boot properly. Each time the phone would power on as soon as I inserted the battery without pressing the power button.

Thinking a full charge wouldn't hurt the situation, I put the phone on the charger, (in a hung boot state) and went out for the night. By Sunday morning the phone was completely dead. I checked the voltage across the +/- terminals on my battery and there is no charge.

What I'm wondering is, did a dead battery cause all the faults I was having, or did the faults put the phone in a state where it won't charge the battery.

Unfortunately, the warranty on my phone has expired. Given I have an expensive paper weight and nothing to loose at this point; I have no issue with disassembling the phone to debug the problem.

Reading through the forum, it looks like at least a few of you are technically competent on the MPx200 circuitry. I'm hoping that someone can provide me with steps for debugging. Specifically, I would like to verify that phone is properly (or not) charging the battery when on the charger. I have access to a voltmeter at home, and if necessary I could probably use the OScope after hours at work.

Thanks,

Jason

[Guest madmaxedcn]

Saturday my phone lost reception so I decided to cycle the power.  The power key wasn't working so I pulled the battery to power down.  After reinserting the battery multiple times I had results varying between a boot hang to a missing SIM message.  I tried with and without my SIM card, but could never get the phone to boot properly.  Each time the phone would power on as soon as I inserted the battery without pressing the power button.

Thinking a full charge wouldn't hurt the situation, I put the phone on the charger, (in a hung boot state) and went out for the night.  By Sunday morning the phone was completely dead.  I checked the voltage across the +/- terminals on my battery and there is no charge.

What I'm wondering is, did a dead battery cause all the faults I was having, or did the faults put the phone in a state where it won't charge the battery.

Unfortunately, the warranty on my phone has expired.  Given I have an expensive paper weight and nothing to loose at this point; I have no issue with disassembling the phone to debug the problem.

Reading through the forum, it looks like at least a few of you are technically competent on the MPx200 circuitry.  I'm hoping that someone can provide me with steps for debugging.  Specifically, I would like to verify that phone is properly (or not) charging the battery when on the charger.  I have access to a voltmeter at home, and if necessary I could probably use the OScope after hours at work.

Thanks,

Jason

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[Guest awarner [MVP]]

Welcome to the site :D

There is an internal 0.5A fuse you can check, it's marked with an F which helps :) (this actually gives the rating for a surface mounted fuse.)

This is the guide HERE to taking the phone apart.

[Guest jasonmgeorge]

I took the phone apart after getting home from work and to my dismay, the fuse is good. I have zero ohms resistance across it and 5V at either end when the charger is plugged in.

I tested the pads that connect to the battery and I had about 0.3V across the outer two (+/- terminals on the battery I beleive). I have no idea what the charging sequence is, however, so this means nothing to me.

Are there any other points I can probe that might help debug the problem?