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SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Posted: April 11th, 2018, 2:03
by jeremyb
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/
Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Posted: April 11th, 2018, 3:33
by arvika
Nice info, good job!
Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Posted: April 11th, 2018, 7:47
by HaQue
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.
Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Posted: April 11th, 2018, 14:05
by NANDoff
nice one!
Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Posted: April 11th, 2018, 14:50
by fzabkar
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.
Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Posted: April 11th, 2018, 15:06
by fzabkar
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.
Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
Posted: April 11th, 2018, 15:24
by fzabkar
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.