WD5000AAKS-75A7B2 Dead. 5v & 12v TVS OK. 0.12v on Smooth
September 30th, 2020, 23:59
Hi all.
Working on a customers 3.5" 500GB drive.
Symptoms - Completely dead.
Customer said it wasn't spinning up, so they tried to install it into an new external enclosure, and somehow TORE OFF the SATA port entirely!
I soldered on a new SATA power/SATA data port (hence why I haven't connected the terminal pins)...
and confirmed it didn't spin up...
Both TVS diodes OK.
R64 and R67 zero Ohms.
Tested PCB while disconnected from actual drive.
Board gets 12v, 5v, and 3.3v OK.
No signs of burns, etc.
No shorted caps.
Pin1 on Smooth L725L controller should be 12v but only getting 0.12v.
Would that indicate Smooth controller internally shorted on 12v rail?
0v either side of D2?
L1, L2 & L3 all show zero Ohms.
Placed card over preamp lines, drive doesn't spin.
Also tried on another WD5000AAKS drive - same result, doesn't spin.
Read through lots and lots of threads here, 9 pages of search results for WD5000AAKS with secondary search for the word "dead".
Where does the 12v come from that is meant to go to pin1?
I've got 12v nearby, and where it come into the board near the power connector...
Even got 15.21v for some reason on C6, on the the side facing the smooth chip, and 11.85 on the other side of it???
I thought caps always had one side connected to ground?
Any help greatly appreciated.
Working on a customers 3.5" 500GB drive.
Symptoms - Completely dead.
Customer said it wasn't spinning up, so they tried to install it into an new external enclosure, and somehow TORE OFF the SATA port entirely!
I soldered on a new SATA power/SATA data port (hence why I haven't connected the terminal pins)...
and confirmed it didn't spin up...
Both TVS diodes OK.
R64 and R67 zero Ohms.
Tested PCB while disconnected from actual drive.
Board gets 12v, 5v, and 3.3v OK.
No signs of burns, etc.
No shorted caps.
Pin1 on Smooth L725L controller should be 12v but only getting 0.12v.
Would that indicate Smooth controller internally shorted on 12v rail?
0v either side of D2?
L1, L2 & L3 all show zero Ohms.
Placed card over preamp lines, drive doesn't spin.
Also tried on another WD5000AAKS drive - same result, doesn't spin.
Read through lots and lots of threads here, 9 pages of search results for WD5000AAKS with secondary search for the word "dead".
Where does the 12v come from that is meant to go to pin1?
I've got 12v nearby, and where it come into the board near the power connector...
Even got 15.21v for some reason on C6, on the the side facing the smooth chip, and 11.85 on the other side of it???
I thought caps always had one side connected to ground?
Any help greatly appreciated.
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Re: WD5000AAKS-75A7B2 Dead. 5v & 12v TVS OK. 0.12v on Smooth
October 1st, 2020, 16:27
The SMOOTH chip generates a boost voltage from the 12V supply. That's what you appear to be seeing at C6. This voltage is required by the VCM circuit.
L3 and D2 would form the negative supply for the preamp. There would normally be -5V on the anode of D2 when the drive is running. This supply is switched on and off by the MCU.
L1, L2 and Q1 (3.3V) would be the Vcore and Vio supplies. Check to see whether they are present. The 3.3V supply is controlled by the SMOOTH chip, so it appears that this part is working.
It could be that your model is one of those that doesn't spin up if it cannot detect a preamp.
L3 and D2 would form the negative supply for the preamp. There would normally be -5V on the anode of D2 when the drive is running. This supply is switched on and off by the MCU.
L1, L2 and Q1 (3.3V) would be the Vcore and Vio supplies. Check to see whether they are present. The 3.3V supply is controlled by the SMOOTH chip, so it appears that this part is working.
It could be that your model is one of those that doesn't spin up if it cannot detect a preamp.
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