Okay… thank you so much Franc… 
Dear fzabkar ,
Thanks for yor help in this forum, I sure appreciate your expertise.
I have a WD 500gb Mybook drive and I saw smoke comming out of it.
I unplugged it and took the board out
Here’s a few pictures of the board .
http://i820.photobucket.com/albums/zz124/fedemati/Logic%20board/DSC09466.jpg
http://i820.photobucket.com/albums/zz124/fedemati/Logic%20board/DSC09474.jpg
http://i820.photobucket.com/albums/zz124/fedemati/Logic%20board/DSC09483.jpg
http://i820.photobucket.com/albums/zz124/fedemati/Logic%20board/DSC09484.jpg
Do you thinks I could change whatever is burnt in the picture , or better yet , where can I buy that burnt piece and what’s called.
kindly
guille
D4 is a TVS diode (Transient Voltage Suppression). The “BUF” marking code indicates a working voltage of 13V.
ISTM that the drive has sustained a serious overvoltage on the +12V supply. Did you overvolt your MyBook with the wrong adapter, eg a 19V laptop adapter?
Assuming there is no additional damage, you can remove D4 by snipping its pins with flush cutters. The drive will work without it, but it will no longer have overvoltage protection on the +12V rail. Be absolutely sure your PSU is OK.
You also need to check the zero ohm resistor, R64. This normally goes open, much like a fuse. If it fused, then you will need to bridge it with a short piece of wire.
If, for continued protection, you wish to replace the diode, the original part number is SMBJ13A:
http://www.datasheetarchive.com/pdf-datasheets/Datasheets-32/DSA-631289.pdf
http://www.st.com/stonline/products/literature/ds/5616.pdf
These should be available from Farnell, Mouser, Digikey, Newark.
Otherwise you can substitute an SMBJ12A. The working voltages are 13V and 12V, respectively, but the breakdown voltages are about 1.5V higher.
Here are my scratchpad style notes:
http://www.users.on.net/~fzabkar/HDD/TVS_diodes.txt
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Dear fzabkar
I accidentally plugged a floppy cable connector 4 pin x 2 on my wd3200 HD (on the jumper slot) and now I think i fried the logic board. It doesn’t smell like burned but my HD doesn’t work anymore,I need a logic board for the hard drive listed below:
WD P/N: WD3200JS-60PDB0
WD Caviar SE
mnf date: 24 feb 2006
DCM: HSBHCAJCA
300 GB
I really need the inside data. Any solution will be thank.
fzabkar - I’ve been going absolutely cross-eyed trying to identify the diode (TVS?) on this logic board I have. It came from an old WD1200JB that died a long time ago, but coming across this forum has made me wonder if this drive could be revived by removing the diode – but I don’t know how to identify it. Thanks - this forum topic has been very interesting and educational!
I searched and came across another thread in which you replied to someone asking you about their logic board, fzabkar. Their drive and logic board are different from mine. But in his pictures, I noticed the chip arrangement and lettering is similar near the power. In particular: C59, L4 and C62. You said to this person that it looked like his board had no TVS diodes and that older drives don’t have these.
My logic board is from a drive made April 2004.
That board doesn’t appear to have any TVS diodes. If your drive spins up with a replacement board, but doesn’t detect, or detects with the wrong capacity or model number, then transplant the 8-pin serial EEPROM chip at location U12, above the WD70C22 MCU, from patient to donor.
If you wish to troubleshoot your board, then remove it from the drive and check the output voltages of the linear regulator chip at U6 (TLE4417). I believe it is similar to the following.
STMicroelectronics ST3L01K7R IC REG TRIPLE 2.6/3.3/8V 7SPAK:
http://www.st.com/stonline/books/pdf/docs/8618.pdf
Cool, thanks for your reply.
In fact, U6 becomes really hot to the touch when power is supplied to the board.
Being a linear regulator rather than switchmode, U6 would normally be quite warm. It may be an idea to measure the resistances between each of its output pins and circuit ground. Do this with power removed. This will locate any shorts on the outputs.
I have a problem similar to the original posters. I accidentally plugged in the wrong power supply (which will teach me to label things when moving) I have tried replacing the enclosure, but the is no power going into the drive.
I am attaching the drive info and a shot of the board. Can you please help me identify the resistors I need to test and cut?
Thank you
http://i1203.photobucket.com/albums/bb397/Fribble42/101_0083.jpg
http://i1203.photobucket.com/albums/bb397/Fribble42/101_0082.jpg
Sorry, your board has no protection diodes. Locations D6 and D5, near the Molex power connector, are unpopulated. 
I can’t be certain from the photo, but your SMOOTH motor controller chip appears to have a burn mark. If so, then the most expedient solution is to replace the board. However, in this case you will also need to transplant the 8-pin serial EEPROM chip at location U12 (near the motor connector) from patient to donor.
I have a Western digital external hard disk: “My Book Essential Edition” 500 gb. I plugged in wrong power adapter and later found it dead. It doesn’t even give me any sound. After going through this thread I believe that some component of my logic board might got damaged because of high watt power supply adapter. Can you please help me out find the solution for my hard disk to get alive? I have all my family pics, important documents and office folders in it. WD P/N: WD5000AAJS-22TKA0 WD Cavair SE mnf date: 27 Jul 2007 DCM: HANCNV2AAB 500 GB WWN: 50014EE200649721 The logic board has the following number: 2061-71477-100 05P XC 4U06 03Y1 1 0005030 8035 If anyone can help me I’d be much obliged. I was quoted a huge amount to recover the data off this drive and I can’t afford it. I am uploading the best possible pictures I could take of the hard disk and the logic board. Let me know if any more details are required. Following are the pictures. http://www.esnips.com/nsdoc/4b36458a-e251-4b99-abb7-1f778f6eb1f8 http://www.esnips.com/nsdoc/efc14bee-2d0d-4a0e-a0a6-4d043bbcb876 http://www.esnips.com/nsdoc/4449881f-1287-40f6-ad2c-2d923b3f26ff http://www.esnips.com/nsdoc/27aa435d-92b7-4f31-95c0-954d0762cc73 Thanks in advance, Arun
Set your digital multimeter on the 200 ohms range and measure the resistances of TVS diodes (D3 and D4) and the resistances of the two zero ohm links (R67 and R64).
http://www.users.on.net/~fzabkar/HDD/WD5000AAJS_TVS.jpg
I suspect that your drive has a shorted 12V TVS (transient voltage suppression) diode. It will have sacrificed itself by going short circuit in order to protect the rest of the electronics. There will be two TVS diodes, one for the +5V rail, and a second, usually larger one, for the +12V rail. The solution is to remove the shorted diode by desoldering it, or by snipping its pins close to its body with flush cutters. If D4 is shorted, then R64 will probably be open circuit. It acts like a fuse. You can bridge it with a wire link. Just be sure your PSU is OK, as you will no longer have any overvoltage protection on the affected supply rail.
If, for continued protection, you wish to replace the diode, then a 5V TVS diode can be substituted with an SMAJ5.0A, and a 12V diode with an SMBJ12A.
They can be ordered from Farnell, Mouser, Digikey.
Hello fzabkar,
I was wondering if you could help me out with my logic board problem as well; I would really appreciate it. I actually have the exact same hard drive as the OP (I found the thread this way), I have taken a picture of my logic board.
http://boonce.org/up/Logicboard.jpg
I hope there is something that I can do about this myself.
I’d really appreciate if you could have a look,
Dan
Danboard, you didn’t say what the problem was, but if you overvolted your drive with the wrong adapter, then the chances are that the 12V TVS diode is shorted. This component is located near the Molex power connector. It is marked as “TB13A” on the body, and designated as D4 on the PCB. D3 is the 5V TVS diode. Zero ohm resistors R64 and R67 behave like fuses when the associated diode goes short circuit. Check them as well. They should measure zero ohms.
Follow the instructions elsewhere in this thread. Make sure your power supply is good.
Ah sorry about that, what happened was my hard drive was on (in an external enclosure) then suddenly I got a power outage. When i tried to turn it back on, the drive wouldn’t start up. I’ve tested inside a machine and the enclosure is fine because i tested another IDE hard drive with it.
Hi fzakbar,
I found the D4 shorted and snipped it out of the board. But still the problem persists. When I plug in the ext hard drive to my computer, I don’t find any sound from hard disc, sems its not rotating also. My system says successfully installed the controller software, but I don’t see the drive in my computer.
Would be really great if you can tell me what can be the issue now.
Thanks again…
Did you check R64? It should measure zero ohms. If it is open, then bridge it with a wire link.
