Hi all, I am new here and am looking for a bit of advice.

A friend of mine connected the wrong power supply to their external hard drive and it stopped working. Upon removing the drive it had 2 burnt out chips, one is the voltage regulator which I can remove but the other chip concerns me...

Seagate 320GB IDE
st3320620a
P/N 9BJ04G-305
Firmware: 3.AAE
Date code: 07272
Site code: SU



Just in case it would work I bought as similar drive as I could find and tried a PCB swap but as expected the drive span up but was not recognised by my PC. The PCB on the new drive was very slightly different but the FW matched.

Am I beyond a DIY fix? There is a lot of music on there which I am keen to recover as ripping his CDs again to iTunes would take months as he is a DJ.

Any help greatly appreciated

I forgot to say, the other burnt chip is the 8 pin above the voltage regulator.

The safest way for you is to stop there, Sean (pcimage) in Peterborough can help you out with this.
And at this stage the cost should be fairly low.
memberlist.php?mode=viewprofile&u=5866


Regards
Bosse

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Your subject title doesn't match your problem description. Which diode(s) were shorted?

Which 8-pin chip are you referring to? Is it the one below the SMOOTH chip, to the right of the 1R2 coil?

In what way are the PCBs "slightly different"?

BTW, AIUI, a straight PCB swap should have worked. Perhaps the preamp has been damaged.

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Sometimes a straight PCB swap doesn't work, even if the fw version is the same on the device label.

If the OP wants to make a serial connector and post the startup log, then we can see more clearly what the problem is.

Or, as Bosse says I can take a look and hopefully fix it for a reasonable charge.

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I'm sorry if my title was incorrect, I am not an electrician so just called the chips/components diodes. Yes you are correct, the small 8-pin is burnt, it is risen on the top and has scorch marks.

I will send a PM to pcimage to see what he thinks

I will dig out the replacement board and post the differences but basically the printing on the chips looked different even though all the chips I could compare had the same model on them. The board number as slightly different (the number was 2 higher than my board).

That burnt chip looks like it might be part of the negative preamp supply. If the 5V TVS diode is shorted, then this would support the idea that the preamp may be dead.

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i guess smooth chip also damages

if you swapped the old PCB with a new one, you will need to change over the ROM chip for the drive to work properly. There are two 8 pin chips, one of them might be the ROM chip that will need swapping to the new board and it might work.

The "ROM" appears to be the 8-pin IC above the jumper block, at the bottom left corner of the Agere MCU.

Each of the other 8-pin ICs appear to be associated with their adjacent coils, so that would suggest that they constitute the onboard power supplies.

In fact here is a better photo:
http://malthus.zapto.org/viewtopic.php? ... =111&p=129

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A backup a day keeps DR away.

Hello everyone.

I figured I would bump this thread since it isn't too old. I have the exact same drive as OP does (although it has a slightly different revision PCB), both TVS IC's seem to be fried as well as another one that I'm not sure what it goes to. I already have a new PCB and the drive does start fine with only power plugged in.


In red are the items that are clearly blown, blue should be the ROM chip which is what I wanted to verify. I've identified it as an Atmel 25F512AN EEPROM, so it seems to be the right guy. If I swap this to the new PCB will the data on the drive be accessible? I will be taking it to work tomorrow where I have a reflow station to get it swapped out, just making sure this isn't in vain.

Here is a pic:

@Protocol, you have correctly identified the "ROM".

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A backup a day keeps DR away.

These seagate boards are annoying me, I have one that I am working on at the moment, messing around and its annoying, made it worse but nevermind, its a 0.99 group of drives I wanted to play with anyway...

Now, to this problem, Yes, I believe that is the ROM chip, Find a matching board and replace the chips and you should be good to go.

But be warned, judging by the damage, it looks like your pre-amp chip inside the drives housing might be blown too, so you will need to have the heads swapped. I am sorry to say that this is a job for a Professional who has the tools and skill to do it.

But check to see if the damage is localized to the board itself first.

Shane

@fzabkar thanks for the confirmation.



We'll see tomorrow if it works or not, the guy this belongs to was quoted some huge amount of money ($1200-$1500) to fix it without them even looking at the drive in the first place. Is there any way to tell if there is internal damage before I get after it with the chip? The power board that belonged in the external enclosure took the brunt of the damage, it looks BAD. I'm wondering what kind of power brick he hooked it up to in order to get that much damage.

Could we see the damage?

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A backup a day keeps DR away.

Sorry for the cell phone pic but it will do in a pinch. This one was definitely on fire.

The large chip is an AP1506 switchmode DC-DC converter. It steps down the incoming 12V supply to produce the +5V supply for the HDD. It is specified to operate up at up to 22V, so provided that the rogue adapter was of the correct polarity, then this chip should probably have survived.

AP1506-50, Anachip, 150kHz, 3A, fixed 5V, PWM Buck DC-DC converter, TO263-5L, 22V input:
http://web.archive.org/web/200502080902 ... AP1506.pdf

The smaller 8-pin chip could be a dual MOSFET that switches +5V and +12V to the HDD. Can you discern any markings on the package?

You stated that both TVS diodes were damaged. Did you actually measure their resistances? Based on the visual damage to the bridge board, I would have expected that the HDD's 12V diode would have been shorted, but the 5V diode may have survived.

As for the component adjacent to the motor controller chip, my own PCB doesn't have anything at this location.

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The 12V is destroyed totally, the 5V blew out the bottom of the package. The small one on the bottom has the marking MLE on it, but it is quite burnt as well around the edges.

The small component is a 12V TVS diode.

1PMT12AT3, ON Semiconductor, Zener Transient Voltage Suppressor POWERMITE, 12V, 175W, marking MLE:
http://datasheet.octopart.com/1PMT12AT1 ... -30310.pdf

If the 5V diode measures open circuit, then the overvoltage may have destroyed the preamp inside the HDA, but that's something for the professionals to determine.

_________________
A backup a day keeps DR away.

Thanks very much for the help, I moved the chip over this morning and the HDD runs up like a champ. Got all the files copied to a brand new drive just to be safe, but it seems to run like new.