January 7th, 2013, 9:22
January 7th, 2013, 9:49
January 7th, 2013, 9:52
January 7th, 2013, 9:59
Touchclarity wrote:ROM is usually located at U12 on the PCB unless it's embedded in the MCU, then you will need professional help on this...
Post a picture, and I'm sure someone will point you in the right direction...
January 7th, 2013, 10:08
w.simon wrote:Hello
Can you make photo of the pcb board ? and post
On the not working pcb look if there are TVS (D3 / D4) and check if the are not 0 ohm.
If they are 0 ohm they burned so you can remove / change for recover datas
If you do PCB swap, you had to swap the U12 chip too.
Good Luck
EDIT : TouchClarity has been faster than me
January 7th, 2013, 10:33
January 7th, 2013, 11:18
Touchclarity wrote:ROM is embedded.....you will need pro assistance on this....
January 7th, 2013, 12:55
Where is the MCU on the attached photo?
Hey mate, D3 & D4 is reading 0.6 ohm...
January 7th, 2013, 17:48
January 7th, 2013, 18:22
sathyan wrote:Where is the MCU on the attached photo?
Rom is embedded in the large Marvell chipHey mate, D3 & D4 is reading 0.6 ohm...
May be you are not checking correctly.
0.6 Ohm is as good as 0 ohm== Short TVS.
Check in the resistance range of the multimeter,( not the diode range)
But , usually , Both the TVS dont fail together.
Also if the TVS diodes have failed , it wont allow your CPU to power on.
As suggested by Touchclarity, this is not a DIY case.
If data is really important, take pro help.
VCM controller may be faulty, but proper diagnosis is necessary ,rather than guess work
DIY attempts can make matters worse,so be careful
January 7th, 2013, 18:23
mr_spokk wrote:IF you desolder the Diods, don't use the same Psu that blowe'd them in the first place...just a warning.
January 7th, 2013, 18:24
Touchclarity wrote:ROM is embedded.....you will need pro assistance on this....
January 8th, 2013, 4:18
synergia wrote:No worries, will check this again later as this is the sympthoms it is giving me on the HDD cradle and won't allow the unit to power on or the WD MyBook Essentials V2 enclosure it was in would not power it up either. I also plugged it into the PC SATA power connector and it would not power the PC up, until i removed the faulty HDD.
synergia wrote:I have a mate who's into SM PCB repairs so if it's the TVS or requires new PCB I will get him to do the ROM swap over.
January 8th, 2013, 10:34
synergia wrote:No worries, will check this again later as this is the sympthoms it is giving me on the HDD cradle and won't allow the unit to power on or the WD MyBook Essentials V2 enclosure it was in would not power it up either. I also plugged it into the PC SATA power connector and it would not power the PC up, until i removed the faulty HDD.
TVS sounds like the culprit. Will let you know later today what my TVS resistance is as 0.6 ohms is as good as 0 ohms.
January 8th, 2013, 10:43
The symptoms suggest TVS failure.
Remove the TVS and use a good Power supply as you have been suggested here.
Do not try to replace the MCU just yet,( let this be the last option)because as Northwind suggested , this is not easy and chances of spoiling the pcb is high.
Remove the TVS and connect it to the SATA port of a PC. If the drive detects , make a clone or copy off the files ASAP.
January 11th, 2013, 3:29
January 11th, 2013, 6:00
synergia wrote:After testing the Diode again D3/D4, I found that D4 was shot! I desoldered the offending diode and reinstalled the PCB back into the main HDD unit and sure enough the HDD powered back up and was able to copy all my data back onto a spare HDD.
I do thank everyone's input, but if you do feel confident in doing it yourself by all means give it a go, after all experts have to start somewhere. If you don't feel like going further in your diagnosis then by all means consult a specialist. Again this TVS would not necessarily have fixed this fault but like a few posts have said, "It's a simple thing to try", do one diagnosis at a time (IF YOU FEEL CONFIDENT).
Thanks heaps again!
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