SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults

[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/

[arvika]

Nice info, good job!

[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.

[NANDoff]

nice one!

[fzabkar]

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.

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.

[fzabkar]

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!

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.

SSREXT -- External Reference Resistance -- a 12Kohm +/- 1% external resistor should be connected to this pin.

[fzabkar]

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.