Phone maintenance guide

From Legacy Portable Computing Wiki

WIP. More images will be included eventually!

This page intends to be an all-encompassing resource about how to keep older mobile phones (and any other portable device, for that matter) in good shape.

The issues described in this page seems to happen to some phone brands worse than others, and storing conditions certainly plays a major role in speeding up or slowing down when they happen.

"Rubber rot"

"Rubber rot" or "rubber reversion" refers to deteriorating rubber products and coatings found in many different portable devices. This can be seen most often on the rubber stops of flip phones and rubber-coated back covers of other kinds of mobile phones. Mobile phone manufacturers such as Motorola made heavy use of rubberized coatings, of which can become a chore very quickly.

Several factors are thought to cause rubber reversion, such as temperature, UV exposure, and simple age.

No matter how little or how much reverting rubber is present, interacting with a mobile phone that has the problem can be downright infuriating, as it will smear on plastic parts of the phone, attracts dust and fibers from cleaning wipes, and seems impossible to remove.

Fortunately, with the right materials, removal of rotting / reverting rubber does not take too terribly long.

Removal

Prerequisites

  • 90% or higher isopropyl alcohol (while 70% alcohol wipes do work with moderate success for this purpose, 90%+ isopropyl alcohol works far quicker)
  • Cotton swabs or other dry wipe
  • Gloves

Steps

Dip cotton swab in the isopropyl alcohol, and then rub the wet cotton swab onto the affected rubber. It will appear to 'melt' and stick to the cotton swab.

You'll most likely need to go through multiple cotton swabs to fully remove the affected rubber spots.

For larger areas, such as rubber-coated back covers, you'll want to use a paper towel or other wipe with isopropyl alcohol applied.

Once the melting rubber starts to adhere to the wipe, either apply more isopropyl alcohol or use another wipe.

When all of the melted rubber is removed, you should be left with the smooth metal or plastic that was behind it.

Gallery

Batteries

As batteries of any kind age, how long they last and how reliable they are is bound to change.

This is especially true for devices from the early 2000s and below, and in the 2020s it is close to a miracle if a device from that age has a working battery.

Lithium-ion batteries

The vast majority of li-ion and li-po batteries found in mobile phones run at 3.7 volts, and have a charging voltage of 4.2 volts.

This page won't go into the specific chemistries and the science behind them, but in short, applying 4.2 volts to a 3.7 volt li-ion battery will charge it.

Other charging voltages

Although li-ion batteries will charge at other voltages, it is strongly recommended that you do not exceed it.

It is possible to charge 3.7 volt batteries using the +5 volts from a USB interface, but this generally is not a good idea. Very cheap li-ion cells without adequate protection circuitry can explode due to overvoltage.

At best, charging 3.7 volt li-ion cells with USB power can be done to "jump start" batteries that appear to be entirely empty (e.g. reads 0.00V on a multimeter), but there are safer ways to go about doing this.

"Reviving" Lithium-ion batteries

Using a bench power supply set to 4.2 volts and constant voltage (C.V) or an external 4.2 volt li-ion battery charger, a seemingly flat phone battery can be 'revived' to charge once again.

This method has been used to get a seemingly flat HTC Wizard battery to fully charge again, and should work on other phones too!

  • Prepare power supply or external 4.2 volt charger
  • Connect the battery to the power supply / external charger. If possible, leave it in the phone.
  • If the power supply reads a current of ~100 to 200 mA (likely displayed as 0.100 to 0.200 A), or the external charger detects a battery, leave it charging for half an hour
  • Now attempt to charge the battery using the phone itself. If the battery was 'revived' successfully, the phone will power on enough to charge.

Nickel-cadmium batteries

Ni-cd batteries were only used in very early 2000s mobile phones and below, and by this point they are very likely unusable.

"Reviving" methods for these batteries are not currently known. (applying 4.2v to a dead 3.7v Ni-Cd battery resulted in zero current being drawn from the power supply)

Unlike li-ion batteries, Ni-cd batteries have a tendency to leak corrosive material in long-term storage. If you have any phones with non-working Ni-cd batteries, discard of them immediately!

Batteries of any type should not be thrown into the landfill. Dispose of batteries (especially leaking ones) at your local electronic recycler(s).

Screen lens adhesive

This issue seems to be primarily caused by storing conditions, but under certain circumstances, the adhesive that holds the screen lens onto the phone may start seeping onto the phone's actual display.

Similar to rubber reversion removal, the issue can be dealt with by using 90%+ isopropyl alcohol. You'll want to have some replacement adhesive on hand, as removing the old, liquifying adhesive will result in the screen lens no longer sticking to the phone.

Removal

Prerequisites

  • 90% or higher isopropyl alcohol
  • Cotton swabs or other dry wipe
  • Gloves
  • Suction cup to remove screen lens
  • Flat plastic spudger
  • Replacement adhesive strips (e.g. Tesa 61395)

Steps

  1. Apply suction cup to screen lens, and then gently pull upwards to loosen the lens from the adhesive
  2. When a large enough gap is present, insert a flat plastic spudger in the space. Move the spudger around the edges of the lens while gently pulling up on the suction cup. (depending on what state the adhesive is, the screen lens may come off from the suction cup pulling alone)
  3. The screen lens should detach from the phone. Set it aside on a dry wipe or other surface that you are okay getting decade-old adhesive on.
  4. Wet cotton swab(s) with the isopropyl alcohol. Rub areas covered by the adhesive with the wet cotton swab. Repeat until no adhesive is left.
  5. Repeat step 4, except on the back side of the screen lens where the adhesive was stuck to. (alternatively, you could submerge the screen lens in isopropyl alcohol and wipe it off that way)
  6. Apply the replacement adhesive strips of your choice where the adhesive was previously located on the phone.
  7. Press the screen lens into the place it was before you removed it from the phone.

After the old adhesive is removed, any previous residue should no longer be present on the actual screen.

Gallery