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 Post subject: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
PostPosted: April 11th, 2018, 2:03 
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Joined: July 30th, 2012, 3:37
Posts: 236
Location: Fairfield, CT USA
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/

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 Post subject: Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
PostPosted: April 11th, 2018, 3:33 
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Joined: October 24th, 2009, 15:22
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Location: Poland
Nice info, good job!

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 Post subject: Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
PostPosted: April 11th, 2018, 7:47 
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Joined: December 4th, 2012, 1:35
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Location: Adelaide, Australia
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.


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 Post subject: Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
PostPosted: April 11th, 2018, 14:05 
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Joined: March 28th, 2018, 13:24
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nice one! :-)


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 Post subject: Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
PostPosted: April 11th, 2018, 14:50 
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Joined: September 8th, 2009, 18:21
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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.

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 Post subject: Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
PostPosted: April 11th, 2018, 15:06 
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Joined: September 8th, 2009, 18:21
Posts: 10844
Location: Australia
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.

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 Post subject: Re: SanDisk 20-99-00092-2 & 20-99-00121-1 Common Faults
PostPosted: April 11th, 2018, 15:24 
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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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