Posts Tagged ‘water damage’

Why Wet Cell Phones Cannot be Repaired (Part 2)

Wednesday, February 10th, 2010

We have already outlined in a previous blog post that water / liquid damaged cell phones are beyond economic repair, if repairable at all.  In this follow up we have decided to outline WHY.  Quite simply, the proper procedure is tedious, time consuming and requires replacement of a significant number of parts.  Keep in mind, that while you may only be experiencing a minor issue (a few keys not working), there can be significant additional latent damage that will lead to additional failures over time.  And if this potential for further damage is not taken into account then it shouldn’t be difficult to realize that the phone cannot be truly repaired as any ‘fix’ likely will be only temporary, until the unforeseen damage materializes.  So, we find it unacceptable to consider a liquid damaged cell phone repaired unless it is done correctly by making sure we address not only the obvious but the not-so-obvious damage as well.  To simply ‘fix’ the issue at hand will result in your spending money on a non guaranteed ‘repair’ with a high probability of future failures.  And repair shops that offer or claim to be able repair liquid damaged phones very obviously lack the knowledge and/or don’t understand why the repairs are not economically feasible.  So, let’s examine the process in some detail.

The first step is up to the user: The battery should be removed IMMEDIATELY.  This will minimize the chance for further shorts by removing the primary electrical source.  (It will not eliminate the threat of damage since there will be an internal battery and stored electrical capacity within the circuitry of the phone.)  Users are smart to rely on internet advice about removing the phone’s battery.  However, there are way too many pointless suggestions offered on the internet about how to deal with wet phones, such as heating the phone with a hair dryer to dry it or “Old Wives”  tale  remedies like using rice to absorb the moisture.  It is important for the owner of a water/liquid damaged cell phone to realize that no ‘internet remedy’ will address the core issue of electrical damage to the phone.   The best advice to follow when you have a water/liquid damaged phone is to get it to a qualified repair shop as soon as possible.

Once a damaged cell phone arrives at the shop it needs to be completely disassembled.  The main PCB needs to be inspected for any visible, catastrophic damage such as de-lamination of the PCB layers or burnt areas.  Any damage of this sort is deemed un-repairable.  Once the unit passes initial inspection, the cleaning / repair / testing procedure can begin.

  • The internal battery will be removed and capacitors need to be discharged and / or removed
  • Most vibe motors, speakers, cameras, microphones, shields will be removed.
  • The PCB will be ultrasonically cleaned for several hours in a specialized cleaning solution.
  • The PCB will be rinsed, dried and inspected.
  • Any residue remaining will be hand cleaned.
  • Removed components are re-installed (using new parts for electro mechanical parts – batteries, capacitors, microphones, speakers, cameras, etc to avoid latent failure and reduce the time needed to test each component individually)
  • Each path / circuit (charging, audio, display, etc) on the PCB must be tested for electrical continuity.
  • Breaks in continuity will need to be isolated by testing the path at  various points to isolate the damaged component.
  • The affected component is replaced and the circuit re-tested.
  • The procedure is repeated until all paths are verified.

Then the process is repeated for secondary PCBs.  In many cases, those secondary boards will simply be replaced.  For any clam shell or ‘flip’ phone, the flexible PCBs will also need to be replaced.

As part of the re-assembly procedure, the Liquid Crystal Displays (LCDs) will be replaced.  Most LCDs are now part of an integrated PCB that does not allow for cleaning and testing.  Since there is a high potential failure rate for LCDs once exposed to moisture, failure to replace them will compromise the repair.

When the foregoing has been completed the unit is re-assembled with a new battery.  This is important because batteries are sealed units, with high probability that they short internally once wet. Since a defective battery can damage the newly repaired cell phone it would be pointless to repair the phone and not replace a potentially damaged battery. With a new battery installed the repaired cell phone is put through a series of final tests to ensure correct operation.

Most phones that we have encountered that were exposed to moisture had NOT been submerged, instead coming in contact with a minimal amount of liquid.   This may lead one to believe that it may be possible to forgo a number of the repair steps previously noted, including replacing flex PCBs, LCDs and batteries.  However, liquid is very pervasive and its affects on electronic circuits is very damaging.  Since any portion / component of a phone that comes into contact with liquid needs to be cleaned or replaced to properly repair the cell phone,  even minimal exposure to liquid will require 2 to 3 hours to evaluate, clean and test the phone.  At shop rates of $50 to $75 per hour, very few phones are even worth repairing, fewer still once the cost for parts is added.

Consequently, based on accepting the work that should be done to properly repair a water/liquid damaged cell phone (assuming it can be repaired), it is not economically logical to perform such repairs, and it would be most prudent to be extremely skeptical of any repair shop that offers or claims to be able to do so because it just can’t be justified.

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Wet cell phones CANNOT be (economically) repaired…

Monday, January 4th, 2010

The number of cell phone ‘repair centers’ that claim they can fix liquid damaged cell phones, then claim a 70% or better success rate is truly incredible.  I say this because, in virtually every case, the proper repair of a wet cell phone will almost certainly cost more than the phone’s replacement value. AND, even if it would be cost-efficient (which is not very likely) it is doubtful there are many (if any!!) places that have the capability to even perform the proper repair.

The typical repair service offered by most shops generally starts with a warning to remove your battery immediately and ship in your phone ASAP.  The actual repair consists of dis-assembly, cleaning the printed circuit board (PCB) by hand scrubbing with a brush, using an ultrasonic cleaning filled with isopropyl alcohol as needed, and possibly replacing parts (like displays), and finishing with reassembly.  These phones are then quickly tested, deemed repaired and returned with no warranty.  At best, this is a quick, temporary fix, but no way does it mean the phone has been truly repaired.  How can this be, you may ask.

Your cell phone is a small computer designed around a densely populated central printed circuit board with an integrated LCD display and keyboard.  There may be secondary PCBs as well as flexible PCBs (the flex cables that connect the two halves).  The PCB is, by definition, designed to mechanically support and electrically connect electronic components (resistors, capacitors, radio chips, etc) using conductive pathways, tracks, or traces, etched from copper sheets laminated onto a non-conductive substrate.  (http://en.wikipedia.org/wiki/Printed_circuit_board).

As expected, liquid creates a significant number of issues with the electrical connections throughout the PCB.  The severity of these issues is higher when the liquid involved contains electrically conductive materials, and the greater the quantity of these materials, the more likely, and more / significant, the damage.  Water, soda pop, milk and most other liquids commonly involved in cell phone damage are electrically conductive to some degree.  The conductive nature of these liquids, combined with the moisture, lowers resistance between the electronic components and the underlying circuit paths.  Lower resistance results in high current within the circuit causing a large amount of energy output within a short time frame leading to damaged components.  Additionally, open or short circuits can occur when deposits left on the board result in bridges or unwanted connections between the leads of board components.  In the most extreme cases, this can lead to arcing and fires. (We have quite a few boards displaying such damage.)

So can water damaged cell phones be repaired?  Depending on the liquid, the amount of time the cell phone was in contact with the liquid, and the actions taken immediately following the liquid damage, it is possible.  Is it likely?  No.  Is it cost effective?  Definitely not.

We will continue this discussion in our next post (http://bit.ly/acsmIN), detailing the proper repair procedure and illustrating what is involved, to better be able to understand why it is not cost effective to repair water damaged phones.

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