Repairing
Electronics repairing is a hobby I started when I was approximately 14 years old for three primary reasons: the ability to obtain functioning hardware for well under resale value, the ability to return a profit off of used devices due to the aforementioned, and the ability to restore already-owned hardware to perfect functionality without having to return it to an OEM, risking data loss/a different model in return/high fees/long wait times/outright rejection.
This page will list some techniques that I find useful. A dictionary of terms I use are at the bottom of the page.
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Dictionary
| "Known good" | In troubleshooting, this refers to using a control variable -- a component which is known to be fully functional, used alongside a device that is
exhibiting issues. This determines if a given issue is caused by a faulty external component, or the device itself. |
| "Trace" | An trace on a circuit board is another name for an electrical path. They will also be referred to as lines, lanes, and paths.
Circuit boards may have multiple layers of traces on a single plane, so a manual repair isn't always possible. |
| "Joint" | This is a completed solder area, with an attached component between two solder points. |
| "PCB" | This can also be referred to as a motherboard, mainboard, main PBA, or printed circuit board. This is the primary board that consists of fiberglass that the primary components of the device, such as the CPU, GPU, RAM, antennas, etc, all connect to. Some PCBs are comprised of many layers, where circuits may be hidden. |
| "IC" | Integrated circuit. This is actually the same concept as a "chip". Chips are self-contained devices that perform their own functions and can be connected to a PCB. An IC is simply a less colloquial name for a "chip". |
| "Solder mask" | A PCB houses traces, which are intended electrical paths to complete a circuit. These traces are usually copper, gold, or sometimes dark green. The rest of the board will be covered in a green layer, which gives motherboards their stereotypical color. That is solder mask, and it helps electricity to complete its intended path without interfering with other circuits. |
| "Flux" | Magic bonding liquid. That's you need to know.
Applying this to a trace will help the solder stick only to the intended target and not the solder mask or other unintended components. It can also assist in heating up the entirety of a joint as flux is a very good heat conductor. This means that touching recently heated flux can harm your skin. Flux should be cleaned after use as it often leaves a residue which can become conductive after use. |
| "Solder" | Magic bonding metal. They can come in different alloy percentages of lead and tin. Lead-free solder tends to have a higher melting point. If you aren't consuming the solder, the presence of lead won't be an issue. Metal does not travel in vapors. |
| "Ground" | Necessary to complete a circuit, or else unneeded voltage would travel into the component which would force it to suffer an overvoltage.
Essentially, sparks go boom without a ground. |
| "Ribbon cable" | Also known as a flex cable or FPC (flexible printed circuit), this is the same concept of a PCB, except using a plastic-like material to house traces, instead of rigid fiberglass. |
| "ZIF" | Zero-insertion force connectors. Most FPCs connect to these. |
| "FPCB" | Flexible printed circuit board. This is a small board where the ends of a FPC terminate. This plugs into a PCB in the same manner as a LEGO. |
| "Microcontroller
unit (MCU)" |
A multi-purpose unit that monitors and controls numerous components of a circuit, usually including power management and clock. |
| "RTC" | Real-time clock. This is not to be confused with the device clock, which is also known as cycle speed. A real-time clock keeps track of the time as a stored integer, usually a raw value from an epoch (usually the Unix epoch). The OS derives time by converting the raw value into a human-readable time format and then applying an offset for the user's applicable time zone. |
Troubleshooting
Before delving into a repair, it is necessary to determine the primary defects of the device. It is very helpful to understand the how the device works internally beforehand, and how each component interacts with each other in order to make the best judgement on whether a job is suitable to fix. Many software issues may have many physical catalysts, and so can hardware errors. In many cases, a device that appears cosmetically functional yet presents with many assorted issues is very likely to suffer liquid damage in some form. This is because a short circuit can either damage many individual components, or a specific component that controls many others, like a microcontroller.
Physical
Physical repairs comprise of primarily cosmetic damage, and can be corrected by replacing a number of components.
ZIF Components
ZIF latches, also known as zero-insertion-force connections, come in a variety of sizes, shapes, and mechanisms. Within most phones, tablets, laptops, and handheld gaming consoles, there are three primary types, and they generally have standardised names. For example, the P6 connector is a four-pin latch-style ZIF that is used for DS and 3DS touch screen receptables.
Electrical
Electrical repairs usually involve some form of direct damage to a PCB and may require soldering, trace repair, and/or use of a multimeter.
Soldering
Soldering involves joining two electronic components using a metal with a low-melt-point called solder.
Desoldering
Most desoldering is achieved using a hot air rework station. The method depends on the type of component, and if it's surrounded or contains any plastic pieces, like most ZIFs.
Standards and symbols
From a manufacturer, a red wires typically contain live voltage, while black wires serve as grounds. This, alongside most standard practices, isn't reliable for devices that have already undergone amateur repair.
Liquid
Liquid damage is inherently unpredictable and should be avoided for all purposes aside from data recovery.
Don't.
While many liquids, including pure water, are not conductive on their own, the impurities that the liquid will inevitably transport from component to component are. A thorough wash in isopropyl alcohol might remove many of these contaminants, but there may still be shorted components which aren't immediately causing errors, and can cause issues at an indeterminate point in the future. A device that has suffered liquid damage may appear to work, but cannot be guaranteed to be reliable and should not be resold as a refurbished device on principle. Metallic components may now be vulnerable to corrosion.
A very good tool to clean a PCB with is an ultrasonic cleaner, assuming the board doesn't have loose surface-mount components. A screen with liquid damage is a lost cause due to the extremely thin layering.