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  • PCB Swap Guide


Every day we receive multiple questions about how to swap hard drive circuit board. Some are seeking help with finding a match, many aren't sure if PCB swap will help, and a lot of people are troubling with getting a failed hard drive to work with new circuit board. We have done a significant research, and found out that limited information about hard drive circuit board replacement that there is, it is often outdated, incorrect, or entirely misguiding. Hard drive PCB retailers claim that it is 1-2-3 to find and replace a defective circuit board, on the other hand - data recovery companies say that nowadays, it isn't even possible to perform a successful swap. Bottom line is, it often is a nightmare to get your hard drive back up and running, when electronic board went bad.

There are few things to know, before you proceed. 

1. Not every hard drive failure is due to circuit board. In fact, we counted about 25-30% data loss scenarious to occure due to failed electronics. Even what often seems to be an obvious sign of a PCB failure, could be a completely different, often mechanical issue. If time is an essense - go to data recovery professional, or contact us for advise.

2. When a circuit board has fried for sure, with modern hard drives, you might need to take a few additional steps in order to make your failed hard drive working again with the new PCB. Do not expect this to be as easy as just a "simple PCB swap".

Hard Drive Diagnostics

So before you go ahead and start looking for a replacement PCB, think about the failure itself. Make sure that sympthoms you are getting are at least a possibility of a failed circuit board.

1. Check your computer cables. We always encourage using an external enclosure for testing purposes, as it is much easier to work with and understand your failed hard drive behaviour.

2. Does your hard drive spin? Try to listen, touch it, or slowly lift it.  If it makes a buzzing sound or a sound like it is "trying" to spin, the failure is most likely a spindle seizure and has nothing to do with the circuit board. If you hear 1 tick, or do not hear or feel anything at all, likely the PCB has fried.

3. If hard drive spins up, try and hear if it makes even quiet ticking or clicking sound. A clicking sound is often indication of a head failure, and rarely a PCB. If you want to give a shot to PCB swap, you have about 10% chance that it will help, so 90% you will end up losing additional money and time. More you play with a clicking drive, more damage it will do to it's surface, possibly resulting in data loss. Seriously consider contacting a data recovery company instead of toying around with failed drive.

4. In case hard drive seem to function normally, but is "not recognized in your computer", issue with the hard drive could be anything. Including, but not limited to - circuit board failure, bad sectors, firmware, mechanical, etc. First, check if hard drive is recognized in BIOS with correct parameters. If it is, then most likely you are dealing with a firmware or logical hard drive failure. Try data recovery software, or contact a data recovery company. Often, they won't charge much for a logical recovery. Replacing a circuit board, when hard drive is properly displayed in BIOS will not likely change anything.

Finding a Suitable Donor Circuit Board

Finding a matching PCB for your hard drive can be difficuit if the failed hard drive happens to be rare, however, most of our customers can find a good match by following our Donor PCB Matching Article here.

Soldering ROM U12 PCB Chip

Getting Hard Drive to Work

So the symthoms are indicating that hard drive circuit board is faulty. You found and purchased an exact PCB match. So now, after swapping the circuit boards, things seem to get better, but hard drive is still not recognized? No worries, that is common, and we will try and help you with this. Many older, and most of the modern hard drives circuit boards contain unique adaptive data in ROM chip. That adaptive data can hold information about accessing your drives system area, amount of activated and total heads there are in a hard drive, head resistance, and much more. Again, that information is often unique! No matter how "close" the match is, even if it is identical in all specs but serial number or came from same assembly batch. Without that unique adaptive info in original PCB - your drive will not properly function and you won't be able to retrieve your data from it.

First, see if this is nessesary for your hard drive by looking at donor matching guide, then see if ROM chip does exist. Usually, the ROM is 8-pin (4-pins on 2 sides) chip, often marked as U12 on Western Digital or U6, U5 on Hitachi. There aren't many 8-pin chips on hard drive circuit boards, often only 1. On the chip, you will likely find a number starting with "25". If you aren't sure which chip to swap, go to hddguru forums. Search around, and if no one discussed your HDD circuit board architecture, then post a question with a detailed picture. Prompt responce is guaranteed. If you cannot find a ROM chip, and are working with a Western Digital hard drive, then it is likely imbedded in a main controller Marvell chip. That chip is extremely difficult to solder, and most of the time experts do not have success with it. Our company offers Free PCB Adoptation Service to customer who have made a purchase from our store. The new PCB will be reprogrammed to work with hard drive, with no soldering including in the process, whatsoever.

Once the chip has been found, next step is to swap it onto the new board. If you do not feel comfortable doing it yourself, send it to us for free service or contact a local computer repair shop. Most of the time, they are able to perform this simple chip swap with no problems. Do not trust it just to anybody, this chip is vital for getting your hard drive back up and running. Overheating and burning it will likely result in data lost forever.

If you have soldering experience, and required tools, then you can try this at your own risk. Tools required are: a hot air station or heatgun, metal tweezers, grip tool, and optionally soldering flux. Begin by gripping the new board to a table, while part of PCB with to-be-soldered chip is not laying on the table and is loosen in the air, so you do not burn table. Apply just tiny bits of soldering flux on all 8-pins of the chip. Turn heatgun or air station to high setting, and with one hand hold the air-generating end half inch away from the chip for about 10-15 seconds, while the other hand has metal tweezers ready to remove chip at any second. Move heat just a bit away from the chip, and try to lift it with tweezers. Do not tear chip from PCB, it should come off with no force at all. Repeat same thing with original board. Make sure to remember which side chip went on the board, as it is important. Next, align ROM chip from old board on new board. Apply heat for 10-12 seconds, remove heat and cool off the board a little bit. Make sure that ROM chip is now tightened in place. Try new board with the hard drive and see if you have any luck this time. If hard drive is not spinning at all, apply some heat to the chip again for a few seconds, and circuit board on hard drive while it is still fairly hot. If it is still not spinning, perhaps you put chip on wrong way. Try turning it 180 degrees and soldering it in again. If still no luck, you might have overburned the chip. At this point, contact us for assistance.


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