[SOLVED] Help identifying components in Seagate Ironwolf 4TB ST4000VN008 ?

[mustava]

Hi All,

I have recently had a PSU die in my server, taking 6 brand new Seagate Iron wolf 4TB drives with it.
All the drives are/were in good mechanical condition.

I have been doing some research on the most appropriate route to revive these drives. Most of what I have found either points to replacing the 5v or 12v TVS Diodes or transplanting the 8-pin BIOS chip onto a new PCB.

Given my options, I figure re-soldering two pins (TVS) instead of 8(bios) is the easiest way - and if that doesn't work, then transplanting the BIOS onto a new PCB.

I am looking at using the following across the 5/12v diodes that read as shorted on the multi-meter.
5v
12v

In the drives I have tested thus far, the components in red test as 0/short on the mm.
The component in Blue seems to test OK, only providing a reading in 1 direction of 700ohms.

Have I correctly identified the bad diode? is there anyway i can find if its the 5v or 12v diode? Ive been unable to find any examples of my exact PCB (100788341-rev-c) but on other seagate boards it appears to be the 5v.
Also, the markings on the two chips
Red/top: AE-03E-M (I believe this is the 5v diode which is reading as short)
Blue-right: 68E-OC607 (I believe this is the 12v diode which is reading as 700ohms)

Images (im not sure why i cant attach these inline?)

https://ibb.co/zRS359d

https://ibb.co/nnYJ3sL

https://ibb.co/TgfHZSk

 

[fzabkar]

Remove the 5V TVS diode (AE) and flow a blob of solder over the two zero-ohm resistors ("000") nearby. These act like fuses and will probably measure open circuit.

If there is no other problem, then your PCB should work. However, you will have no protection if you overvolt it again.

 

[mustava]

Remove the 5V TVS diode (AE) and flow a blob of solder over the two zero-ohm resistors ("000") nearby. These act like fuses and will probably measure open circuit.

If there is no other problem, then your PCB should work. However, you will have no protection if you overvolt it again.

Hi fzabkar,

thank you for your advice! I was hoping you would drop by this post, thank you for materials, your posts have been most of the basis of my research
could i ask you a few more detailed questions? I am going to have to do this 6 times...so I want to make sure I cover my bases.

• Have I correctly identified the 5v & 12 v diodes?
• Where are the 0ohm resistors for the opposite diode?
• If I order 6 donor boards, am I better off transplanting the bios or trying to repair the individual components with the diodes linked above?

I checked the 0ohm resistors, they test as follows with the multi-meter
@200ohms setting: 52.4 - 70 in either direction
In continuity mode: beep/0hms which i think makes sense?
Does this mean they are in working order? my assumption is that they dont need to be flowed given they are passing current?

 

[fzabkar]

The zero-ohm resistors should measure 0.0 ohms on the 200 ohms setting. Compare the resistors on the 5V side with those on the 12V side. Continuity mode will beep when the resistance is below a certain value (dependent on your meter). It seems to me that your resistors are partially open. BTW, you should measure resistance in the absence of power (sorry if this is obvious).

"Have I correctly identified the 5v & 12 v diodes?" - Yes

"Where are the 0ohm resistors for the opposite diode?" - the horizontally mounted pair near the screw hole at the top right corner,.

"If I order 6 donor boards, am I better off transplanting the bios or trying to repair the individual components with the diodes linked above?"

If you damage the ROM ("BIOS") ICs, your data recovery cost will skyrocket, assuming you can find one of the few people who claim to be able to recover from such a situation. Therefore my advice would be to try a repair, as it would be less risky. If you want to do it properly, purchase the needed TVS diodes (SMAJ5.0A) and replace the open resistors with a single 2A smt fuse.

There are 4 octagonal shaped coils (inductors) on the PCB surrounding the SMOOTH IC. Measure the resistances between a screw hole and each of the 1R0 and 3R3 coils.

Just above and to the left of the 6R8 coil is a Schottky diode ("M4 + U4"). Measure the resistance between a screw hole and the anode (non-striped end) of the diode.

These measurements will tell us if any of the onboard supply voltages are shorted to ground.

If there are no shorts, and after you have removed or replaced the TVS diode, and bridged or replaced the zero-ohm resistors, then power up the board on its own and measure the voltages between a screw hole and each of the resistance test points. I'm guessing you will see 0.9V (Vcore), 1.8V (Vio), and -5V (preamp supply). Don't worry if -5V is not present, as the MCU will probably turn it off when it can't detect the preamp (which is on the headstack inside the drive).


Edit:

Just an unrelated observation. The thermal pad for the MCU is off-centre, and the square imprint would suggest that the casting doesn't line up with the MCU. Is that a sloppy design, or did you disturb the pad?

 

[mustava]

The zero-ohm resistors should measure 0.0 ohms on the 200 ohms setting. Compare the resistors on the 5V side with those on the 12V side. Continuity mode will beep when the resistance is below a certain value (dependent on your meter). It seems to me that your resistors are partially open. BTW, you should measure resistance in the absence of power (sorry if this is obvious).

"Have I correctly identified the 5v & 12 v diodes?" - Yes

"Where are the 0ohm resistors for the opposite diode?" - the horizontally mounted pair near the screw hole at the top right corner,.

"If I order 6 donor boards, am I better off transplanting the bios or trying to repair the individual components with the diodes linked above?"

If you damage the ROM ("BIOS") ICs, your data recovery cost will skyrocket, assuming you can find one of the few people who claim to be able to recover from such a situation. Therefore my advice would be to try a repair, as it would be less risky. If you want to do it properly, purchase the needed TVS diodes (SMAJ5.0A) and replace the open resistors with a single 2A smt fuse.

There are 4 octagonal shaped coils (inductors) on the PCB surrounding the SMOOTH IC. Measure the resistances between a screw hole and each of the 1R0 and 3R3 coils.

Just above and to the left of the 6R8 coil is a Schottky diode ("M4 + U4"). Measure the resistance between a screw hole and the anode (non-striped end) of the diode.

These measurements will tell us if any of the onboard supply voltages are shorted to ground.

If there are no shorts, and after you have removed or replaced the TVS diode, and bridged or replaced the zero-ohm resistors, then power up the board on its own and measure the voltages between a screw hole and each of the resistance test points. I'm guessing you will see 0.9V (Vcore), 1.8V (Vio), and -5V (preamp supply). Don't worry if -5V is not present, as the MCU will probably turn it off when it can't detect the preamp (which is on the headstack inside the drive).


Edit:

Just an unrelated observation. The thermal pad for the MCU is off-centre, and the square imprint would suggest that the casting doesn't line up with the MCU. Is that a sloppy design, or did you disturb the pad?

5v 0hm resistors measure at 53.5 @ 200ohms setting
12v 0hm resistors measure at 00.2 which i guess is as close to 0 as it can be?
3r3 coil = 110
1r0 = 120 on the first , 140 on the second
I couldn't get a reading from the 6R8 or Schottyky.

I'm not sure collectively what the above means ? does it mean where i get a reading is shorted to ground? that sounds bad .

In regards to the thermal pad...i thought the same thing, but i havent touched it. sloppy design it looks the same on all of the drives.

 

[fzabkar]

The 5V zero-ohm resistors are open.

All the other measurements are OK. It means there are no other shorts or obvious problems on the PCB.

As for the sloppy design, it could be that there is an earlier version of the PCB with a different layout. Seagate's engineers then thought, oh well, close enough.

 

[fzabkar]

Here are two more measurements that you can do.:

http://www.users.on.net/~fzabkar/HDD/ST4000VN008/HDA_pads.jpg

These are the supply voltage test points for the preamp IC inside the drive (on the headstack).

Firstly measure the resistance between a screw hole and each pad. Do this with the PCB off the drive. There should be no short.

Now locate the same test points on the other side of the PCB by following the thruholes for each pad. Then, with the PCB mounted on the drive, measure these same resistances. If there is now a short, then this means that the preamp is damaged.

 

[mustava]

Here are two more measurements that you can do.:

http://www.users.on.net/~fzabkar/HDD/ST4000VN008/HDA_pads.jpg

These are the supply voltage test points for the preamp IC inside the drive (on the headstack).

Firstly measure the resistance between a screw hole and each pad. Do this with the PCB off the drive. There should be no short.

Now locate the same test points on the other side of the PCB by following the thruholes for each pad. Then, with the PCB mounted on the drive, measure these same resistances. If there is now a short, then this means that the preamp is damaged.

I get a reading of 0.03 from the second pin with the PCB off.
On the rear of the PCB it doesn't look like the pads are exposed? the only exposed through-holes. I tried to trace to the closes attached fused but there is no obvious testing point.

Remove the 5V TVS diode (AE) and flow a blob of solder over the two zero-ohm resistors ("000") nearby. These act like fuses and will probably measure open circuit.

If there is no other problem, then your PCB should work. However, you will have no protection if you overvolt it again.

The 5V zero-ohm resistors are open.

All the other measurements are OK. It means there are no other shorts or obvious problems on the PCB.

so if these are shorted, I replace these with a 2AM SMT fuse like this one? if there is a more appropriate part let me know...fast blow? slow blow?
and i assume i install it across all 4 pads (2 each side) and polarity doesn't matter?

Thank you! I am learning a lot !

 

[fzabkar]

I'm working from photos, so I often get it wrong. Maybe the second pin is ground and the third pin is one of the supplies? You can verify this for yourself if you measure the resistance between the -5V test point at the diode and each of the 3 pads. Also measure the resistance between the 5V zero-ohm resistors and each of the 3 pads.

Then you will know whether the pinout is -5V, Ground, +5V, or something else.

I think the fuses can be fast blow, although I haven't been able to confirm this (the smt markings aren't very useful).

I can help you to find the corresponding test points on the other side of the PCB if you can upload an equally good photo.


Edit:

Have you removed the 5V TVS diode? If not, then you will be measuring the resistance of the diode, which is 0.0 ohms. You need to cut out this shorted diode with flush cutters, or desolder it.

 

[mustava]

I'm working from photos, so I often get it wrong. Maybe the second pin is ground and the third pin is one of the supplies? You can verify this for yourself if you measure the resistance between the -5V test point at the diode and each of the 3 pads. Also measure the resistance between the 5V zero-ohm resistors and each of the 3 pads.

Then you will know whether the pinout is -5V, Ground, +5V, or something else.

I think the fuses can be fast blow, although I haven't been able to confirm this (the smt markings aren't very useful).

I can help you to find the corresponding test points on the other side of the PCB if you can upload an equally good photo.


Edit:

Have you removed the 5V TVS diode? If not, then you will be measuring the resistance of the diode, which is 0.0 ohms. You need to cut out this shorted diode with flush cutters, or desolder it.

I haven't de-soldered it yet, I was planning to order the replacements first.
Here are some additional photos of the back and front of the board.

20220330-124841

Image 20220330-124841 hosted in ImgBB

ibb.co

20220330-1214856

Image 20220330-1214856 hosted in ImgBB

ibb.co

 

[fzabkar]

These are the corresponding test points on the other side of the PCB:

http://www.users.on.net/~fzabkar/HDD/ST4000VN008/HDA_pads_bottom.jpg

My initial guess was correct. The pinout appears to be -5V, +5V, Ground.

Edit:

Just one more thing. Can you measure the resistance between 5V and ground at the SATA power connector?

https://pinoutguide.com/Power/sata-power_pinout.shtml

It bothers me that you are measuring 50 ohms as the resistance for the 5V zero-ohm resistors on all your boards. Is there a cable attached to the SATA power connector?

 

[mustava]

These are the corresponding test points on the other side of the PCB:

http://www.users.on.net/~fzabkar/HDD/ST4000VN008/HDA_pads_bottom.jpg

My initial guess was correct. The pinout appears to be -5V, +5V, Ground.

Edit:

Just one more thing. Can you measure the resistance between 5V and ground at the SATA power connector?

https://pinoutguide.com/Power/sata-power_pinout.shtml

It bothers me that you are measuring 50 ohms as the resistance for the 5V zero-ohm resistors on all your boards. Is there a cable attached to the SATA power connector?

I get 52.5ohms on pins 4 and 8 on the connector. does that sound right?

I just double checked two of the other boards... the 5v resistors seem to be closed (no readings- that's good right? the 5v diodes seem to be dead though) and only the first boardreads 50ohms.

 

[fzabkar]

It seems that all but one pair of zero-ohm resistors are good, so you might get away with 6 diodes and 1 fuse.

Good luck.

The 52.5 ohm reading is probably a partially open resistor. You can recheck the reading after removing them. It just looks unusual to me. All the ones I've encountered over the years in various storage forums have been either open or closed.

 

[mustava]

I will order enough to cover my bases I will keep you posted with progress!
To clarify with the fuse, I solder 1 fuse to the 4 pads where the 0ohm resistors were right?

Thank you so much for your help, I'm learning a lot

 

[fzabkar]

I will order enough to cover my bases I will keep you posted with progress!
To clarify with the fuse, I solder 1 fuse to the 4 pads where the 0ohm resistors were right?

Thank you so much for your help, I'm learning a lot

Yes, just one fuse. Good luck.

 

[mustava]

Yes, just one fuse. Good luck.

@fzabkar

So good news and bad news...
I finally got all the components shipped and was able to replace the 5v diode.

I tried to replace the 000 resistors with a a fuse as directed, however the fuse is far too long for the space of the 4 pads.
I could not for the life of me get the fuse to stick to the pads given it was extending past them on both sides.

In the end, all 4 pads ended up bridged (given they are all 5v i assume this is the same as the resistors).
Plugging in the drive, everything spins up and the drive appears in device manager and partitions show- everything looks good so far.

Any advice on how the handle the fuse or what the risk is of leaving the 4 pads bridged? I havent attempted other drives yet..

 

[fzabkar]

In the early days there were no fuses, only TVS diodes. The drives relied on the computer's PSU to shut down in the presence of an external short.

 

[mustava]

In the early days there were no fuses, only TVS diodes. The drives relied on the computer's PSU to shut down in the presence of an external short.

Update:
It appears all 5 Seagate drives now work with the 0hm jumpers bridged & replace diode. I will aim to recover the data and then address the lack of a fuse.


I have one drive left to recover which I'm not sure where to start.
Its a WD Red 4T (WD40EFRX). The components all look very different and seem to test differently.

Any suggestions where to start?

https://ibb.co/8gPnqD0

https://ibb.co/DkRhnLM

 

[fzabkar]

"U2" and "SU6" are the 5V and 12V TVS diodes.

The tiny components with a white "S" on a black background are fuses.

 

[mustava]

"U2" and "SU6" are the 5V and 12V TVS diodes.

The tiny components with a white "S" on a black background are fuses.

Thanks!
Both U2 & SU6 do not give me a short in either direction, reading 179ohms in one direction.
Sounds like these both might be ok?

For the fuses, the 5v Fuse give me no reading (so i guess i replace this?) and the 12v fuse reads open.

Does that sounds correct?

 

[fzabkar]

A fuse should read 0.0 ohms. This is the same reading that you see when you touch the two probes together.

 

[mustava]

A fuse should read 0.0 ohms. This is the same reading that you see when you touch the two probes together.

Its official, all drives are currently online. backed up and working back in their raid setup - unbelievable! 6/6 drives restored, I cant believe it. I am completely blown away. Stressful experience.

Thank you so much for your patience and wisdom @fzabkar !