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Flash Drive Help
http://forum.hddguru.com/viewtopic.php?f=10&t=36891
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Author:  ddrecovery [ May 31st, 2018, 20:12 ]
Post subject:  Flash Drive Help

This flash drive had a broken connector. Board seems physically okay but still not recognized when connected. The LED does not light up. Caps test okay. Data lines to CPU have continuity. Would like some additional testing advice before completing a chip off.

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Author:  HaQue [ May 31st, 2018, 21:25 ]
Post subject:  Re: Flash Drive Help

Check the 2 "000" resistors for continuity, plug in and put tweezers over to make circuit.
also, is C8 sldered ok? hard to tell, may just be shadow on the bottom.

Sometimes BGA balls get lifed if drive was bent or stressed.

Author:  fzabkar [ May 31st, 2018, 22:20 ]
Post subject:  Re: Flash Drive Help

Zero-ohm resistors R100 and R101 appear to be connecting PCB ground to the metalwork of the USB connector. I can't see how they could possibly affect the circuit. Instead I'd be checking the two 1R0 resistors (R1 & R3, 1 ohm) for continuity.

I'd also confirm that the crystal oscillator (U6) is oscillating.

U4 appears to be a switchmode regulator IC. I expect that the junction of L1 and C17 would the Vcore supply for the flash controller.

Author:  Minho [ June 1st, 2018, 12:29 ]
Post subject:  Re: Flash Drive Help

I would also try removing/re-soldering the micro-controller. If the drive took physical damages (broken connector), it's possible that some of the pads beneath the IC legs have cracked. Removing the controller will allow you to see if the pads are in good condition. Any damaged pads can be repaired.

Author:  ddrecovery [ June 2nd, 2018, 18:56 ]
Post subject:  Re: Flash Drive Help

fzabkar wrote:
Zero-ohm resistors R100 and R101 appear to be connecting PCB ground to the metalwork of the USB connector. I can't see how they could possibly affect the circuit. Instead I'd be checking the two 1R0 resistors (R1 & R3, 1 ohm) for continuity.

I'd also confirm that the crystal oscillator (U6) is oscillating.

U4 appears to be a switchmode regulator IC. I expect that the junction of L1 and C17 would the Vcore supply for the flash controller.

Resistors do show continuity.
I changed out the crystal just to make sure.
There is no voltage at the junction of L1 and C17 (also no voltage to the LED) so that area could be our issue.

HaQue wrote:
Is C8 sldered ok? hard to tell, may just be shadow on the bottom.

Yes that is okay, just a shadow.

Minho wrote:
I would also try removing/re-soldering the micro-controller. If the drive took physical damages (broken connector), it's possible that some of the pads beneath the IC legs have cracked. Removing the controller will allow you to see if the pads are in good condition. Any damaged pads can be repaired.

While I have not removed the controller, I checked the pads under the microscope and tacked them all down again.

Author:  fzabkar [ June 2nd, 2018, 19:38 ]
Post subject:  Re: Flash Drive Help

Can you tell us the markings on U4?

Can you measure the voltages across C23 (V1) and C17 (V2)?

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reg.jpg
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Author:  jeremyb [ June 3rd, 2018, 18:23 ]
Post subject:  Re: Flash Drive Help

HaQue wrote:
Sometimes BGA balls get lifed if drive was bent or stressed.
Agreed

Author:  Minho [ June 4th, 2018, 10:11 ]
Post subject:  Re: Flash Drive Help

Minho wrote:
I would also try removing/re-soldering the micro-controller. If the drive took physical damages (broken connector), it's possible that some of the pads beneath the IC legs have cracked. Removing the controller will allow you to see if the pads are in good condition. Any damaged pads can be repaired.

While I have not removed the controller, I checked the pads under the microscope and tacked them all down again.[/quote]

I had one that passed the microscope inspection but when I lifted the controller, the pads lifted with the IC. Sometimes the damage occurs at the junction between the trace and the pad and these can often be underneath the IC. If everything else looks good, then lift the controller to rule out all possibilities.

Author:  ddrecovery [ June 4th, 2018, 12:00 ]
Post subject:  Re: Flash Drive Help

jeremyb wrote:
HaQue wrote:
Sometimes BGA balls get lifed if drive was bent or stressed.
Agreed

Yep agreed, but want to explore every angle with this one first as I am not sure about the BGA chip. I have not removed it yet so I do not know exactly what chip is is, but the markings on the chip are HGKM3TC 1614. Size is 12mm x 14.5mm. I have tried searching for it but have not found it in any database. The flash drive is a PNY 128GB

Author:  ddrecovery [ June 4th, 2018, 12:23 ]
Post subject:  Re: Flash Drive Help

fzabkar wrote:
Can you tell us the markings on U4?

Can you measure the voltages across C23 (V1) and C17 (V2)?

Markings on U4 is ETC
V1 - 0.303v
V2 - 0.v

Author:  fzabkar [ June 4th, 2018, 16:16 ]
Post subject:  Re: Flash Drive Help

It appears that U4 (RT8010) is not getting an input voltage (Vin, pin 3). We need to find where Vin is coming from. I suspect that the flash controller may be reducing the USB +5V input to +3.3V via an internal LDO regulator. Then this +3.3V supply would be applied to the Vin pin of U4 to generate the controller's Vcore supply.

I would confirm that +5V is present at each end of resistors R1 and R3 (1R0). I would then use the multimeter's continuity function to determine which pin of the controller is connected to the Vin pin of U4, if any. If the controller is receiving +5V but is not outputting +3.3V, then it would be suspect. Alternatively, U4 could be powered from the +5V input, so I would test for that possibility as well.


RT8010GQW, Richtek, 1.5MHz, 1A, High Efficiency PWM Step-Down DC/DC Converter, 2.5V to 5.5V input, marking ET, adjustable:
http://www.richtek.com/assets/product_file/RT8010=RT8010A/DS8010A-10.pdf

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RT8010_app_cct.gif
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Author:  jeremyb [ June 4th, 2018, 16:44 ]
Post subject:  Re: Flash Drive Help

Wouldn't it be funny if by removing the NAND chip the controller booted up and we found out it was simply a broken pad under the NAND chip.

Author:  ddrecovery [ June 4th, 2018, 17:03 ]
Post subject:  Re: Flash Drive Help

fzabkar wrote:
It appears that U4 (RT8010) is not getting an input voltage (Vin, pin 3). We need to find where Vin is coming from. I suspect that the flash controller may be reducing the USB +5V input to +3.3V via an internal LDO regulator. Then this +3.3V supply would be applied to the Vin pin of U4 to generate the controller's Vcore supply.

I would confirm that +5V is present at each end of resistors R1 and R3 (1R0). I would then use the multimeter's continuity function to determine which pin of the controller is connected to the Vin pin of U4, if any. If the controller is receiving +5V but is not outputting +3.3V, then it would be suspect. Alternatively, U4 could be powered from the +5V input, so I would test for that possibility as well.


RT8010GQW, Richtek, 1.5MHz, 1A, High Efficiency PWM Step-Down DC/DC Converter, 2.5V to 5.5V input, marking ET, adjustable:
http://www.richtek.com/assets/product_file/RT8010=RT8010A/DS8010A-10.pdf

R1 and R3 - 0.25v
Controller pin voltage from U4 is 0.3v
We definitely seem to have a power issue.

Author:  fzabkar [ June 4th, 2018, 17:26 ]
Post subject:  Re: Flash Drive Help

What are the voltages across C104 and C8? What are their resistances?

Author:  ddrecovery [ June 4th, 2018, 17:42 ]
Post subject:  Re: Flash Drive Help

fzabkar wrote:
What are the voltages across C104 and C8? What are their resistances?

Both caps read 0.25v.
Can I measure resistance of a Cap while its on the board?
Diode mode readings of both these caps is 591.

Author:  fzabkar [ June 4th, 2018, 17:56 ]
Post subject:  Re: Flash Drive Help

ddrecovery wrote:
fzabkar wrote:
What are the voltages across C104 and C8? What are their resistances?

Both caps read 0.25v.
Can I measure resistance of a Cap while its on the board?
Diode mode readings of both these caps is 591.

Neither cap is shorted, so the problem must be at the host end. What voltages do you measure at each of the USB pins?

Author:  jeremyb [ June 4th, 2018, 18:14 ]
Post subject:  Re: Flash Drive Help

Tim what model controller does this flash drive have?

fzabkar wrote:
I suspect that the flash controller may be reducing the USB +5V input to +3.3V via an internal LDO regulator. Then this +3.3V supply would be applied to the Vin pin of U4 to generate the controller's Vcore supply.


Phison controllers usually don't do such trickery. Besides, it adds to the cost of the flash drive.
If I had to guess because its BGA, Vcc is 3.3v and VccQ is 1.8v.

Author:  ddrecovery [ June 4th, 2018, 18:15 ]
Post subject:  Re: Flash Drive Help

4.3v, not sure why its not 5v. This is also wired to a new connector so we can rule that out.

Author:  jeremyb [ June 4th, 2018, 18:19 ]
Post subject:  Re: Flash Drive Help

ddrecovery wrote:
4.3v, not sure why its not 5v.

That's not good, try taking the DC/DC converter out of the circuit. Something is pulling amperage.

Author:  fzabkar [ June 4th, 2018, 18:25 ]
Post subject:  Re: Flash Drive Help

ddrecovery wrote:
4.3v, not sure why its not 5v. This is also wired to a new connector so we can rule that out.

Unless you have miswired the USB pins, then ISTM that you must have a problem with the thruhole at C8.

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