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SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
http://forum.hddguru.com/viewtopic.php?f=10&t=36680		 Page 1 of 1
Author:  jeremyb [ April 11th, 2018, 2:03 ]
Post subject:  SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
I wrote an article on SanDisk 20-99-00092-2 & 20-99-00121-1 common faults for anyone who's interested.
These are old drives however the NAND chips are often encrypted and replacing two passives will bring most drives back to life.

https://www.recovermyflashdrive.com/sol ... -1-faults/
Author:  arvika [ April 11th, 2018, 3:33 ]
Post subject:  Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Nice info, good job!
Author:  HaQue [ April 11th, 2018, 7:47 ]
Post subject:  Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
this can be extended to checking the resistor near USB header for open circuit on many standard Phison controller based UFD's such as verbatim store'n'go, emtec etc. From memory I think they are 2R2 value. Symptoms are usually no LED at all.
Author:  NANDoff [ April 11th, 2018, 14:05 ]
Post subject:  Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
nice one! :-)
Author:  fzabkar [ April 11th, 2018, 14:50 ]
Post subject:  Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
HaQue wrote:
this can be extended to checking the resistor near USB header for open circuit on many standard Phison controller based UFD's such as verbatim store'n'go, emtec etc. From memory I think they are 2R2 value. Symptoms are usually no LED at all.

In his blog, jeremyb wrote:
The first fault originates from the overvoltage protection circuitry provided by a 1.3-ohm (?) resister (sic), which fails open should too much current flow through the USB connector. This presents itself as a very dim led light or no led light.
Author:  fzabkar [ April 11th, 2018, 15:06 ]
Post subject:  Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
jeremyb wrote:
I wrote an article on SanDisk 20-99-00092-2 & 20-99-00121-1 common faults for anyone who's interested.
These are old drives however the NAND chips are often encrypted and replacing two passives will bring most drives back to life.

https://www.recovermyflashdrive.com/sol ... -1-faults/

Thank you!

jeremyb wrote:
The second fault is a mystery resistor (I don’t know what it’s for); the original value is 23k-ohms however I find replacing it with a 57.6k-ohm resister can magically bring the flash drive back to life fixing the “endless blinking light” fault and many other miscellaneous failures.

Could this be a precision resistor (usually a different colour)? I suspect it biases (?) the USB port in some way that I don't understand.

from JMicron datasheet wrote:
SSREXT -- External Reference Resistance -- a 12Kohm +/- 1% external resistor should be connected to this pin.
Author:  fzabkar [ April 11th, 2018, 15:24 ]
Post subject:  Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
fzabkar wrote:
Could this be a precision resistor (usually a different colour)? I suspect it biases (?) the USB port ...

In Silicon Motion reference circuits the same resistor is designated as RREF and has a value of 300 ohm 1% for the SM3255QF controller and 680 ohm 1% for SM3257EN. I believe it is often white in colour.
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