Clip plus vs. 3xAA alkaline batteries (aka 4.5V) - Part 2: Repair

[newClipUser]

Long time ago, I started this topic to share my experience about running a Clip+ on 3 AA alkaline batteries:
http://forums.rockbox.org/index.php/topic,27046.0.html

It went pretty well for a long time. It's been a while, so I can't really remember when and how, but at some point, the charger/voltage converter IC didn't want to take this anymore. The result is as follow: the sansa clip still works fine when powered over USB, but the processor will get super hot when beeing powered by anything on its connectors where the li-ion battery was (even with the old battery resoldered on). So I guess the charger or converter IC is malfunctioning.
The question is: does any of you know which of those small components the charger IC or voltage converter is? I would like to repair my little usefull sansa clip+. Sure, I could buy a new one, and I actually don't really use it any more. But I want to do it for the sake of learning and experience.
My friends have a reflow oven and other means to help me replacing the components once I identify the malfunctioning ones.
So, any help and advice would be greatly appreciated.

Thanks!

[saratoga]

The charger and regulators are built into the CPU.  Although if the CPU itself still works fine over USB power, it might be some other part on the board that failed.  Is it actually the main processor that gets hot, or something near it on the board?

[newClipUser]

The charger and regulators are built into the CPU.  Although if the CPU itself still works fine over USB power, it might be some other part on the board that failed.  Is it actually the main processor that gets hot, or something near it on the board?

it's definitely the processor, I touched it when I had it opened up to resolder the li-ion that I desoldered  years ago. I also tried to power it from my variable bench power supply. The processor be come a heatplate when I power it via the battery connectors.
Is it a common issue that the voltage converter inside the CPU gets damaged?
I found some one selling his clip plus over craigslist. He said his clip plus doesn't charge anymore (or something like that), anyhow, it works when beeing powered via usb. I'm thinking of buying that one and hoping that it isn't the same issue. Maybe it's just that his li-ion battery failed and I can swap the batteries. However this solution isn't really what I had in mind. Maybe I can replace the CPU without damaging other parts.

[[Saint]]

While it is technically possible to replace the SoC package, with a heat gun/reflow station and solder paste, time plus costs vs. effort, divided by probable outcomes,  makes it a largely flawed endeavour in my opinion.
There's every chance that you would buy another device that is failed in some way to re-purpose the SoC package, and then break both board irreparably trying to do the swap.

There's a reason why this stuff is mass produced with pick and place machines.

Obviously what is considered a worthwhile pursuit to you, compared to me, will probably differ.
In my opinion I think it would be infinitely more practical for you to just buy a known good second hand or refurbished device instead of buying another broken device and hoping to make one working device out of two broken ones.

But that's the wonderful thing about opinions, they're opinions, not universal truths.


[Saint]

[newClipUser]

While it is technically possible to replace the SoC package, with a heat gun/reflow station and solder paste, time plus costs vs. effort, divided by probable outcomes,  makes it a largely flawed endeavour in my opinion.
There's every chance that you would buy another device that is failed in some way to re-purpose the SoC package, and then break both board irreparably trying to do the swap.

There's a reason why this stuff is mass produced with pick and place machines.

Obviously what is considered a worthwhile pursuit to you, compared to me, will probably differ.
In my opinion I think it would be infinitely more practical for you to just buy a known good second hand or refurbished device instead of buying another broken device and hoping to make one working device out of two broken ones.

But that's the wonderful thing about opinions, they're opinions, not universal truths.


[Saint]

Thanks for your advice, I also think that the efford needed to do the swap and the probability of a positive outcome isn't really preferable. Maybe I should just live with that flaw and build my damaged clip+ into a portable boom box, as it works fine when beeing powered via usb. I expect it to be less power efficient running from usb power, but the boom box will have a huge battery(compared to the tiny li-ion battery of the clip+) and it doesn't really matter.
The reason I'm considering all possibilities to repair/reuse my clip+ is that I just can't stand the thought of throwing it away after it served me well and still could. Thigns tend to grow on me .
I'm on the road for some more days, so I can't really have a closer look at my clip+, maybe you can tell me: is the li-ion battery directly connected to the CPU? Is there any chance there could be a damaged component between them, that cause the overheating in the CPU?

Thanks again!