My S7 is dead... Can anyone help?

[automobilklub]

Hello everyone. I am new to the forum, just bought an ideos s7 tablet. Model 103. It is faulty as does not turn on. It supposed to be simple repair, actually not even repair, just charger and maybe battery replace. But as I ordered and received those, still there is no sign of life in it. Have checked both battery and psu-battery has 3,8V and charger is fine also-5V at the output.
I have stripped it down and found that there is no memory module installed (saw another pic on this forum and there was a memory chip). Also, close to the power socket seems that some component is also missing. (ImageShack Album - 4 images). Don't know too much as couldn't find service manual, don't know correct voltages for test poits/components leads. If anyone could shed some light on it (ie. some voltage levels/values at components from pic 2-they seem to be power related), I would really appreciate it. Thank You!

 

[automobilklub]

Hi. Just spotted, on another website, that on the motherboard there is a place with graphic chip-my mb does not have this one (russian website- S7 , pic 4 in the middle of the page, next to memory chip). Is that right?!
And should there be any light suggesting charging on the case? ie. top right corner?
Thanks

 

[vexx]

Hmm, although pictures you put are too small to see, I saw some soldering pads. Did you purchase new unit with warranty or used one?

 

[automobilklub]

Hi. Its used device, seller said its only power supply issue. Tried to upload better pics but couldn't. It says: "this is not a valid image file". I can make better ones and send directly to you if you don't mind. Services like imageshack anly allow up to 1Meg pics. Will try to upload them again though. I have found on this russian/belarus website some good pics (S7 pic 4 is exactly the area), and it seems that there is a memory chip and graphic one which both are missing on my mobo... Don't know why and actually even if those should be there. Maybe my model (S7-103) doesn't have those?

 

[automobilklub]

Just managed to measure power consumption: its 0,05A from the power supply when connected. No matter if I press the power button. The same reading with battery in or not. When used battery only to power on the S7, it's voltage dropped from 3,76V to 3,75V only, so nothing basically. Checked some mb voltages as well and there is 4V here and there, some 2,7V; 1,4V as well so seems like the fuse and primary circuit are ok. No idea what to do next. Thanks for your reply, hope to get it fixed. Bye!

 

[automobilklub]

Managed to upload better pics:
http://imageshack.us/photo/my-images/802/dscf0026v.jpg/
http://imageshack.us/photo/my-images/59/dscf0017rt.jpg/

On the right hand side there are small pics that when clicked, enlarge...

 

[v0vik]

Hi automobilklub.
On your pictures it right.
All is as it should be.
In your model, no internal flash memory and hdmi output.

 

[automobilklub]

Oh thanks, thats a bit of relief. At least nothing is missing. So only "deadness" issue to be solved... Will try to track positive and negative signals from psu if I got some more time. Maybe will manage to find broken component or circuitry. Thank you again.

 

[v0vik]

Most likely you have a broken Qualcomm PM7540 power management chip.

 

[v0vik]

I think it will be easier to find a working board, not to fix this.

 

[automobilklub]

I think I got an access to this ic replacement. Don't have hot air rework station though. Will try to replace it. Thanks

 

[automobilklub]

ok. This may sound stupid, but I can't find this pmic qualcomm PM7540. Where is it located then?

 

[v0vik]

Uploaded with ImageShack.us

 

[v0vik]

but I still think it's better to buy the main board.
it will cost $ 20-40

 

[vexx]

but I still think it's better to buy the main board.
it will cost $ 20-40

Where? It is so cheap.