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Replacing PCB on Hitachi HDT725025VLA380
Posted: May 30th, 2020, 14:41
by stefax2001
Hello,can you help me?
I have 2 HDDs:
First one is:
Hitachi Model:
HDT725025VLA380P/N:
0A33423MLC:
BA2367Main controller IC:
0A29626PCB Label:
Board number:
F 0A29531 01And second is:
Hitachi Model:
HDS721616PLA380P/N:
0A33932MLC:
BA2357Main controller IC:
0A29625PCB Label:
Board number:
F 0A29531 01First hdd pcb is fried and second hdd is full of bad sectors.
Is it possible to replace pcb on first hdd with pcb from second hdd (I know i will have to replace 8-pin chip)?
P.S. Sorry for my bad english.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 30th, 2020, 15:07
by fzabkar
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 30th, 2020, 15:18
by stefax2001
1. As long as your board Sticker is 0A53047 and Main Controller Chip is 0A29626 and Board Number is 0A29531 ,our board is same as yours in hardware
Well i guess i can't use second hdd as donor
.
tnx for help.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 30th, 2020, 15:26
by fzabkar
What's wrong with the original PCB?
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 30th, 2020, 15:32
by stefax2001
fzabkar wrote:What's wrong with the original PCB?
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 30th, 2020, 15:53
by fzabkar
That's the 5V TVS diode. It appears that your drive sustained an overvoltage on the 5V input. Hitachi drives aren't very well protected, so there is a risk that the preamp is damaged.
Do you have a multimeter? Can you measure the resistance of the diode, D4, and the adjacent resistor, R5?
TVS Diode FAQ:
http://www.hddoracle.com/viewtopic.php?f=100&t=86
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 30th, 2020, 16:31
by stefax2001
fzabkar wrote:That's the 5V TVS diode. It appears that your drive sustained an overvoltage on the 5V input. Hitachi drives aren't very well protected, so there is a risk that the preamp is damaged.
Do you have a multimeter? Can you measure the resistance of the diode, D4, and the adjacent resistor, R5?
TVS Diode FAQ:
http://www.hddoracle.com/viewtopic.php?f=100&t=86
D4:
0ΩR5:
0Ω
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 31st, 2020, 14:33
by fzabkar
Am I right in assuming that the drive now causes your PSU to shut down? If so, then remove D4 and your PCB will probably work again, albeit without protection on the 5V input.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 31st, 2020, 19:16
by stefax2001
fzabkar wrote:Am I right in assuming that the drive now causes your PSU to shut down? If so, then remove D4 and your PCB will probably work again, albeit without protection on the 5V input.
Yes PSU shuts down when i connect contacts of broken diode.
I checked resistance of diode D4 and resistor R5 again (with different multimer) and got
-1018Ω for D4 and -1658Ω for R5???A bit dumb question,but did i make some mistake or what?
Should i still remove D4?
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: May 31st, 2020, 20:42
by fzabkar
stefax2001 wrote:Yes PSU shuts down when i connect contacts of broken diode.
What do you mean by this?
I wanted to know whether the PSU shut down when the broken HDD was originally connected to it. You didn't say how the drive came to be damaged.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 1st, 2020, 4:31
by stefax2001
fzabkar wrote:What do you mean by this?
I wanted to know whether the PSU shut down when the broken HDD was originally connected to it. You didn't say how the drive came to be damaged.
What i meant when i said:
stefax2001 wrote:Yes PSU shuts down when i connect contacts of broken diode.
Was this:
- Top plastic part of D4 is melted.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 1st, 2020, 19:53
by fzabkar
Your statement implies that you connected a PSU to the diode rather than to the HDD, in which case it makes no sense. Or do you mean that you "reassembled" the broken diode and then reconnected the HDD to the PSU???
Whatever you did, your latest measurements indicate that the diode has gone open circuit, and resistor R5 is now also open. IIUC, this resistor is in series with the 5V supply to the preamp, so there is a real possibility that your preamp is shorted. You can test for this possibility by measuring the resistance between ground and R5, and then comparing the result with the PCB on and off the drive.
It goes without saying that you should check the 5V and 12V outputs of your PSU. Obviously there was an overvoltage on the 5V output, so either the PSU is faulty, or you have used the wrong modular cable.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 2nd, 2020, 10:43
by stefax2001
fzabkar wrote:Your statement implies that you connected a PSU to the diode rather than to the HDD, in which case it makes no sense. Or do you mean that you "reassembled" the broken diode and then reconnected the HDD to the PSU???
I normally connected PSU to HDD with molex and then "reassembled" diode.
fzabkar wrote:Whatever you did, your latest measurements indicate that the diode has gone open circuit, and resistor R5 is now also open. IIUC, this resistor is in series with the 5V supply to the preamp, so there is a real possibility that your preamp is shorted. You can test for this possibility by measuring the resistance between ground and R5, and then comparing the result with the PCB on and off the drive.
When you said "PCB on and off the drive" you mean literally disassembling PCB from HDD?
Anyway i got -1003Ω for both measurements on and off.
fzabkar wrote:It goes without saying that you should check the 5V and 12V outputs of your PSU. Obviously there was an overvoltage on the 5V output, so either the PSU is faulty, or you have used the wrong modular cable.
I already checked PSU and got: 5.27v and 11.70v
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 2nd, 2020, 15:33
by fzabkar
The resistor should have a value of 0.47 ohms.
I would measure the resistance to ground at the preamp end, if you haven't done so already.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 2nd, 2020, 18:59
by stefax2001
fzabkar wrote:The resistor should have a value of 0.47 ohms.
I would measure the resistance to ground at the preamp end, if you haven't done so already.
I got this.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 2nd, 2020, 19:44
by fzabkar
You can try a donor PCB, but be prepared for a bad preamp, in which case you may be wasting your money.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 2nd, 2020, 20:53
by stefax2001
So donor PCB should be compatible?
stefax2001 wrote:This HDD (with bad PCB):
Hitachi Model:
HDT725025VLA380P/N:
0A33423MLC:
BA2367Main controller IC:
0A29626PCB Label:
Board number:
F 0A29531 01Donor HDD:
Hitachi Model:
HDS721616PLA380P/N:
0A33932MLC:
BA2357Main controller IC:
0A29625PCB Label:
Board number:
F 0A29531 01
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 2nd, 2020, 21:08
by fzabkar
They have different MCUs (0A29625 vs 0A29626). I'm not a DR pro, but I would think that the PCBs would be incompatible.
Re: Replacing PCB on Hitachi HDT725025VLA380
Posted: June 3rd, 2020, 8:23
by stefax2001
Ok,thank you.