Author Topic: Some caps and resistors came off, can I leave them off? pic inside  (Read 446 times)

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Offline Lisa5Topic starter

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I was trying to replace a larger memory size for my ereader by re-balling, and I accidently knocked off the caps / resistors highlighted in red.

Do I need to replace these? Or can I ignore?

If I have to replace, how can I identify the types and farads etc.

 

Offline Kim Christensen

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Re: Some caps and resistors came off, can I leave them off? pic inside
« Reply #1 on: May 25, 2024, 11:43:55 pm »
You need them. If they weren't needed, then the bean counters would have made sure they weren't installed.  ;D

I take it that you lost them? Then good luck figuring it out without a schematic or reverse engineering.
 

Offline Gyro

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Re: Some caps and resistors came off, can I leave them off? pic inside
« Reply #2 on: May 26, 2024, 11:45:09 am »
One of those 'capacitors' is an inductor (the rightmost one), definitely needed.

As for values, if you don't still have the parts or the manufacturer's schematic, you can't - you might try the datasheet of the Mediatek IC, U18), there might be an application circuit.

EDIT: Otherwise, it looks as if you've lost wifi (and GPS?), maybe you can retain some use by side-loading books over USB.
« Last Edit: May 26, 2024, 12:04:07 pm by Gyro »
Best Regards, Chris
 

Offline Lisa5Topic starter

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Re: Some caps and resistors came off, can I leave them off? pic inside
« Reply #3 on: May 26, 2024, 12:24:24 pm »
You need them. If they weren't needed, then the bean counters would have made sure they weren't installed.  ;D

I take it that you lost them?

I understand they have a purpose somewhere, but the question is, is it required to use the device.
For example a dead power on/off LED is superficial, and doesnt effect using the actual device for its intended purpose.

I have lost the parts unfortunately.


One of those 'capacitors' is an inductor (the rightmost one), definitely needed.

As for values, if you don't still have the parts or the manufacturer's schematic, you can't - you might try the datasheet of the Mediatek IC, U18), there might be an application circuit.

EDIT: Otherwise, it looks as if you've lost wifi (and GPS?), maybe you can retain some use by side-loading books over USB.

Hello Chris.

I wouldnt mind side loading if I cant find inductor.

Would the device be safe to power on? I havnt tried just to prevent breaking it.

 

Offline Gyro

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Re: Some caps and resistors came off, can I leave them off? pic inside
« Reply #4 on: May 26, 2024, 12:38:29 pm »
The other components look to be capacitors (probably decoupling for various pins) and the inductor is probably in the path to one of the RF filters (you would be wise to download the MT6631N datasheet (which, luckily, is available on a web search) and tracing to check that it doesn't go to a supply pin.

Once you have checked that, your reballing hasn't caused any shorts, and there is no other damage outside the area of the photo, I can't see that you would cause any further damage by powering it up.


P.S. Datasheet link... https://archive.org/download/mediatek_202304/MT6631_External_Data_Sheet_v02a_%2820160421%29.pdf

EDIT: If you can do the 'leg work' and identify exactly which pins the missing parts are connected to, it might be possible to make an educated guess about values, or what functionality will be missing (eg. wifi might work on 2GHz but not 5GHz band).
« Last Edit: May 26, 2024, 12:47:23 pm by Gyro »
Best Regards, Chris
 


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