Hitachi PCB Swap- Same HD P/N, MLB, PCB P/N but BA# Mismatch

[Magnus_CA]

Hi Folks,

I have this working 250GB Hitachi Deskstar:

Model: HDT722525DLA380
P/N: 0A31636
MLC: BA1487
PCB P/N: 0A29223 BA1438

I have a non-spinning equivalent 250GB Hitachi with these specs:

Model: HDT722525DLA380
P/N: 0A31636
MLC: BA1487
PCB P/N: 0A29223 BA1292

As I pointed out in bold, everything matches but the second half of the PCB p/n.

What are my chances of the pcb swap (assuming I swap U7) being successful on the non-spinning drive?

Thanks in advance for the replies,

Magnus

[Magnus_CA]

It may help to include pictures...

Here's the PCB from the dead drive (it won't spin up):


Here's the PCB from the working drive:

[loki]

http://www.hddzone.com/conditions.html confirms that you need the first two lines on the sticker to match.

[fzabkar]

You need to swap U5. That's the "NVRAM".

If you are handy with a multimeter, measure the voltages at Q3, Q1, D2118 (Q2 ?).

Also measure the voltages at the two 100uH coils (L1 and L3). That will be the negative supply for the preamp.

[Magnus_CA]

You need to swap U5. That's the "NVRAM".

If you are handy with a multimeter, measure the voltages at Q3, Q1, D2118 (Q2 ?).

Also measure the voltages at the two 100uH coils (L1 and L3). That will be the negative supply for the preamp.

Thank you for the reply. I have a multimeter sitting in front of me and yes, D2118 is Q2. I wouldn't call myself handy with it unless I need to check continuity or resistance but I'm a quick study. Sorry for the newb question but what point do I use for ground? Can I use one of the mounting screws?

[Touchclarity]

Although these 2 boards look the same, they are in fact different, hence the different number on the second line. As far as I can see the motor controller chip is different on the donor to the patient, and this may make all the difference to the success of the recovery. I usually try to match both main chips (MPU and MC) just to be sure.

[fzabkar]

I would use the ground pins at the Molex power connector, below the L1 coil.

Set your meter on the DC voltages ranges, either 2VDC or 10VDC or whatever is appropriate. Be very careful not to short adjacent pins, otherwise major damage will result.

If you're not comfortable making these measurements, then practice by measuring the voltage of a 1.5V alkaline battery or a 3V lithium coin cell, or something similar.

[Magnus_CA]

fzabkar,

I got the voltages. I got 3 different readings at 3 points for Q1, Q2, and Q3 so I added a reference to the contacts I measured on the picture below.

Voltage of Q1 @ position 1, 2, 3 = 3.28, 1.52, 2.59
Voltage of Q2 @ position 1, 2, 3 = 3.28, 5.03, 3.92
Voltage of Q3 @ position 1, 2, 3 = 2.61, 1.56, 3.28

Voltage of L1 = 0.02
Voltage of L3 = 5.06



I don't know where the numbers should be but I would love for the repair to be as easy as exchanging a discrete component rather than sourcing a PCB.

Thanks again for the help!

[fzabkar]

I've been through this exercise for a similar board:
hitachi-deskstar-hdt722525dlat80-spin-t18986.html

It appears that Q2 is an NPN pass transistor in a +3.3V regulator that supplies the Vio voltage for the MCU, SDRAM, U5 and U7. It is working properly.

Q1 and Q3 appear to be PNP pass transistors that supply 1.6V and 1.5V for the MCU core and some other logic. They appear to be OK, if the other thread is any guide.

However, your measurement for L1 doesn't look right. It is suggesting that the negative supply voltage for the preamp is missing. I would confirm this voltage measurement, once with the board attached to the drive, and then with the board removed. Instead of the coil, you could use the group of 3 plated through-holes between L1 and L3, as in the following photo clip:
http://www.users.on.net/~fzabkar/HDD/HD ... eg-reg.jpg

[Magnus_CA]

I will re-test with drive attached and removed and post my results. BTW, my measurements above were taken with the ribbon cable detached. Thank you so much for your help.

[Magnus_CA]

fzabkar,

I retested the voltages with the ribbon cable attached. I used a different power supply this time so I rechecked all the transistors using the transistor contacts again (not the thru holes)

(Note: the red wire to the molex power connector was outputting 4.93V)

Voltage of Q1 @ position 1, 2, 3 = 3.27, 1.52, 2.58
Voltage of Q2 @ position 1, 2, 3 = 3.27, 4.90, 3.93
Voltage of Q3 @ position 1, 2, 3 = 2.60, 1.56, 3.27

Voltage of L1 = -3.03
Voltage of L3 = 4.93



Thank you.

[fzabkar]

Your voltages look OK now, assuming the other thread is any guide.

I don't know what is wrong with the drive, but it appears that the power supplies and the motor controller are functional, at least to some extent. You could try measuring the voltages at the motor terminals while the drive is powering up to see if the motor controller is trying to spin the motor. If there is no activity, then any further electronic troubleshooting will require a scope or logic analyser. If the Infineon MCU is not brain-dead, then it should be able to communicate any error condition to a diagnostic tool, but that's something that I can't help you with.

I think your only DIY option now is to find a matching PCB and move the NVRAM chip. Hopefully this IC is OK.