Missing component? - Sandisk USB Pen

[kpeddie]

Anyone got an idea what component is missing from this?
Bottom right of the pcb there appears to be two solder pads where something has once lived but is now missing? Cant find a picture of one of these online to identify

Any ideas? Left pad is ground

Thanks

Attachments

[kpeddie]

Well, not sure if anything was supposed to be there but found a leg on memory chip lifted slightly, now reading mostly...

[fzabkar]

The photo is poor, but it could be a filter capacitor on the +3.3V supply. Measure the voltages on each pin, or check their continuity to ground and to the Vcc pins of the NAND flash.

[HaQue]

it was a cap. not exactly the same but the general schematic doesn't change much.

http://www.flash-extractor.com/library/SanDisk/20-99-00098-1/20-99-00098-1__45_c3_95_65__1x1
You could probably replace it with one from another stick but finding the value would be difficult unless these caps are all pretty much similar value, and the purpose is what Fzabkar said, and possibly if you are simply close "enough" it will work. My electronics theory doesn't extend far enough though to know!

hopefully you can copy enough off ok.

If you were in AU I'd offer to buy it as I don't have one of those Sandisks yet.

[MarkGreenwood (KE)]

HaQue

im having a clear out soon...

Il keep an eye open for one for ya..

[HaQue]

Thanks Mark!

[jeremyb]

mine measures at 9.8uf

[kpeddie]

Found a similar pen and removed what appeared to be a similar cap, made no odds. Still read the same as before, basically a bit of file system damage. Guessing some file system damage was either present before or that reading without that cap has caused some corruption in the memory chip.

Thanks

[MarkGreenwood (KE)]

could be either....

the DC filter cap is there simply to stabilize the DC current feed to the controller... ie filter out HF noise caused by the forever changing current draw that correlates directly with R/W requests..

With out this cap in place the DC feed to the controller will be getting an unstable noisy power feed.


This would cause undesirable operation..

The severity of this depends highly on the overall quality of the power feed.