Category Archives: Repair Resources

Repair Workshop Lesson Plans and Materials

In 2024, we hosted two two-week workshops. One was for ~50 students in grades 5-7, and the other for ~50 students in grades 7-9. Here we include example lesson plans for both sessions, as well as age appropriate slides.

 Materials / Space Requirements

  • Large well ventilated room with long worktables
  • Around 6 supervised soldering stations with:
    • Fan or ventilation
    • Soldering iron
    • Solder
    • Desoldering Iron
    • Third hand
    • Wire cutters
    • One adult instructor
  • Screwdrivers: We distributed screwdrivers from a number of different kits (around 15 different sized kits of screwdrivers) at the front, depending on what students needed. We found its important to have as much variety as possible, including many different tips, and long-handled screwdrivers.
  • Devices to disassemble / repair: We had around 10 toasters and ten hairdriers. These can be found for ~5 each at thrift stores, or at the recycling depot. We also asked students to bring in their own broken devices if possible.
  • Cleaning materials: Some fans were dusty etc. We had damp cloths, wet wipes, and hand sanitizer on hand
  • Safety equipment: First aid kits, fire extinguisher etc.
  • Snacks

Electronic Design and Repair Workshop: Session 1 Outline

Slides: Repair Workshop Week 1 (Grades 9-12) Repair Workshop Week 1 (Grades 9-12).pptx
9:00 – General Introductions:
Lets start with a quick introduction to the workshop, what everyone can expect and what our goals are.
  • Introduce the instructors
  • Go over the plans for the workshop
  • Brief motivation for the workshop (an introduction to electrical and computer engineering, hands-on experience with electronic repair, and a discussion of how engineering can relate to sustainability and waste)
  • Ask students why they are there and what they would like to learn
  • Activity: Give tables/groups a chance to introduce themselves to each other and come up with a team name.
9:15 – Introduction to safety and equipment:
We’ll go over basic safety when working with electronics. We’ll avoid ever having to plug in the devices without close supervision, but can still talk about dangers of electronic repair and how they can be mitigated. We can also go over the equipment at their stations.
  • Avoiding electric shocks: The difference between AC/DC power, identifying and being careful with capacitors, avoiding plugging anything in etc.
  • Safe soldering: What is soldering and how can it be dangerous? Discuss fumes, burns and ventilation
  • General safety: keeping a clear workstation, tying back hair, being careful during disassembly
    and asking for help when required.
  • Activity (for younger age-group): Spot the safety-related problems in a picture of students
    working at a lab station.
9:30 – Introduction to Ewaste – Motivating Repair
Why is repair important? We can start with a discussion of ewaste, and how it is harmful to the environment.
  • Ewaste: How much ewaste is there? Where is it sent? What are the environmental and social dangers associated with electronic recycling and disposal.
  • Embodied carbon: Discuss the carbon produced during the production / recycling of electronics,
    compared with operational carbon. Life cycle analysis
  • Solutions: Why repair is important, but why it is difficult. Planned obsolescence.
  • Activity: Think back to the last time they threw out an appliance or device. Why? Why was repair hard? What could have been done to deal with the situation more sustainably?
9:45 – Disassembly of a device
Lets have them disassemble their group’s device early on so they have a real life circuit to look at during discussions of circuit components, circuit diagrams. We can provide each group with either a toaster or hairdryer
  • Activity: Take apart their group’s device. Doing this carefully can take some time.
  • Discussion of how this went. Was it easy? What made it hard/easy?
10:00 – Circuit Components
Now that they have a real-life circuit in front of them, we can go through different electrical components, what they are used for, what they typically look like and how to identify them.
    • Resistors
    • Capacitors
    • Integrated circuits and chips
    • Motors
    • Switches
  • Activity: Identify the main components on their disassembled circuit and draw them / describe them on a worksheet.
10:15 – Drawing a Circuit Diagram
To understand how a circuit works, we need to look at how the components are connected and how electricity flows between them. A clear way to do this is to make a circuit diagram that maps out the electrical components and how they are connected.
  •  What is a circuit diagram?
  • How does electricity pass through a circuit? (things connected in parallel versus in sequence)
  • Activity: Draw a circuit diagram of their circuit and how the components are connected.
10:30 – Break
15 minute break
10:45 – Voltage, Current, Resistance
The younger and older age groups might have different amounts of experience and different ability levels here. In both cases though, we can give a brief review / introduction / overview of the ideas of resistance, current, voltage and power through the analogy of pipes and water
  • Current – the amount of water passing through a pipe
  • Voltage – water pressure
  • Resistance – pipe size
  • Short circuits and open circuits – blocked pipes and leaks
  • Basic circuit equations (for older students)
  • Activity (for older students): Solve for voltage / current / resistance in a few simple example circuits.
11:00 – Using a Multimeter
Analyzing, debugging and repairing a circuit typically involves using a multimeter. We can go through and practice a few different types of measurements done using multimeters.
  • Testing connectivity
  • Measuring resistance
  • Measuring capacitance
  • Activity: Measure the resistance of a resistor, and investigate the switches in their circuit. Label measured values (resistance, capacitance etc) on the circuit diagram.
11:15 – Electronic failure and repair
Now that we understand a working circuit, what could cause this circuit to break?
  • Discuss common causes of failure: burnt out / disconnected wires, damaged components, blown
    fuses
  • Brainstorm how this could happen for their devices, and other possible causes for failure –
    crumbs stuck in the toaster electromagnet, fuses from hot hairdryers.
  • Activity: Given a scenario where, for example, the toaster lever doesn’t stay down. As a group we can go through the process of debugging this. Eg. When the lever is pressed down, does the toaster get hot? Check the connectivity of all the components? Does the switch still work? Are there crumbs in the electromagnet?
11:30 – Designing for robustness and repairability
We can wrap up things by talking about how to design electronics that are better – that are easier to repair and that are less likely to break.
  •  Design practices for robustness and design tradeoffs
  • Design practices for repairability and design tradeoffs
  • Activity: In groups, come up with an improvement to your device, and present the new and improved device.
11:50 – Conclusions
We’ll finish up by reviewing what we went over during the workshop, talking about what to expect in the next workshop, and asking for feedback and questions.
  • Review of what we did and learned
  • Explaining the plans for the next lesson and what to expect and bring
  • Question time

Electronic Design and Repair Workshop: Session 2 Outline

Slides: Repair Workshop Week 2 (Grades 9-12) Repair Workshop Week 2 (Grades 9-12).pptx
9:00 – General Introductions:
Lets start with a quick introduction to the workshop, what everyone can expect and what our goals are.
  •  Introduce the instructors
  • Go over the plans for the workshop
  • Review the motivation for the workshop and what topics we covered during Session 1.
  • Activity: Give tables/groups a chance to introduce themselves to each other (likely the groups
    will be different)
9:15 – Review of safety and equipment:
We talked about this during the first session, but its important, so lets review it again.
  • What safety issues and precautions do they remember from the last week? What have they forgotten?
  • Activity (for younger age-group): Spot the safety-related problems in a picture of students working at a lab station.
9:30 – The repair process – how to approach a repair.
We will have them bring broken devices from home. They can choose one to try and repair. We can first go through the basic steps of repair though:
  • Approaching a repair: What works/ doesn’t work? When did it stop working?
  • Activity: Take a look at the device they brought. What works and what doesn’t? What is the history of the problem?
9:45 – The repair process – Disassembly of the device
Lets have them disassemble their group’s device early on so they have a real life circuit to look at during discussions of circuit components, circuit diagrams.
  • Activity: Take apart their group’s device. Doing this carefully can take some time.
  • Discussion of how this went. Was it easy? What made it hard/easy?
10:00 – The repair process – understanding the circuit
Now that they have a real-life circuit in front of them, we can review different electrical components, and drawing a circuit diagram.
  • Resistors, Capacitors, Integrated circuits and chips, Motors, Switches
  • Activity: Identify the main components on their disassembled circuit and draw a circuit diagram
    to the best of their ability.
10:30 – Break
15 minute break
10:45 – The repair process – what could have broken?
Its not always easy to figure out, or visible what the problem with a circuit is, but there are some common problems that we can go over to start with.
  • Common problems and why they happen: Blown fuses, burnt out capacitors, resistors,
    disconnected wires.
  • Review how to use a multimeter to check connectivity, resistance etc.
  • Activity: Take a look at the circuit and look for obvious problems, like disconnected wires. Try to go through each component checking that it is connected and working.
11:15 – The repair process – fixing a problem
Hopefully we found the problem in the circuit. Here we can talk about how to fix basic problems, and what to do if that isn’t possible.
  • Soldering – how to fix disconnected wires and replace components
  • Finding and ordering new parts. Discuss right to repair legislation.
  • Activity: Can the circuit be repaired? We can have soldering stations set up to repair things where possible.
11:30 – Presenting to the group
Every repair is different, and the same thing (eg. A toaster) can be designed in many different ways. We can have each group briefly present their device, the process they used to disassemble and attempt to repair it, and how it could be improved to make it more repairable or durable.
  • Activity: In groups, with flip-charts, prepare a brief presentation of the broken device, the
    circuit diagram, what broke (or a guess as to what broke), how it could be fixed, and what could
    be done by designers to prevent or improve the problem.
11:50 – Conclusions
We’ll finish up by reviewing what we went over during the workshop and asking for feedback and questions
  • Review of what we did and learned
  • Question time

Staying safe during repair

In the eKitchen, we will mostly be working with small low-power household appliances and consumer electronics. Repairing larger appliances is outside the scope of this post. Nonetheless, it is important to consider safety even when working with relatively low power devices.

Individual Safety

Before starting to do any work, check that you are prepared:

  • Clothing: Don’t wear loose clothing that might fall into the circuit, or get in the way.
  • Jewelry: Remove rings or dangling metallic jewelry.
  • Hair: Tie back long hair.
  • It is a good idea to wear protective gloves and glasses if in doubt.

Setting up your station safety

Check also that you have set up your station and equipment safely:

  • Check for tripping hazards – extensions cords, or overcrowded outlets can be unsafe.
  • Keep your work area well lit
  • Work on a stable, dry surface

Before working on a new device

  • Check for safety warnings on stickers, and understand these tips.
  • Generally, turn off and unplug the device, and remove the battery. It might be necessary to measure voltage or current, in which case only power on the device only when performing these measurements.
  • Understand how the device works – don’t be connecting things blindly for example. Be careful during disassembly – you never know when something might be spring loaded.
  • Capacitors can store charge, which can be dangerous in some circuits. Always discharge large capacitors, as discussed below.

After repairs

Older electronics may contain toxic chemicals like lead and mercury. Wash your hands when you are done, and don’t eat or touch food when handling electronics.

Safe Soldering

When soldering, there are some additional safety tips:

  • Work in a well ventilated area: Solder fumes can be toxic. Ideally set up a fan and work near a window.
  • Be mindful of lead: Solder can contain lead. We will try to provide only lead free solder, but the solder in older electronics would likely not be lead free. Wash your hands when you are done.
  • Be very cafeful with the iron: Soldering irons get extremely hot and its easy to burn your fingers. Always be mindful of this. Also, only set the soldering iron down on the iron stand, and don’t leave it unattended.
  • Keep your workspace clear, and make sure that you have enough space. Also make sure that there is no chance of someone tripping on the soldering iron power cable.

Discharging Capacitors

Large capacitors can be quite dangerous, as they can store a lor of charge. Capacitors are typically cylindrical and may look a bit like battery cells. In the eKitchen we are going to be avoiding working with high power electronics with large capacitors, but it is very important to discharge all capacitors nonetheless. You can check the charge on a capacitor using the voltage setting of a multimeter.

To discharge a capacitor, connect a resistor across the capacitor. We will have one available for this purpose. Alternatively, in some cases you can use a screwdriver or a multimeter.

Avoid / exercise special caution …

Certain types of appliances and electronics can be particularly dangerous:

  • PC power supplies, camera flashes and TVs and monitors contain high-voltage capacitors. Ensure they are discharged before doing anything else.
  • Batteries: Never puncture or bend a battery, and be cautious with batteries that appear damaged. If you notice a battery smoking or swelling, step away.
  • Microwaves: We won’t be working with microwaves in this course as they can be especially dangerous in terms of high voltage capacitors, radiation etc.
  • Cathode ray tube displays: We probably won’t come across any CRT displays these days, and won’t be working with them. These have very high voltage capacitors and dangerous vacuum tubes.

Multimeters for Repair

Maybe you haven’t used a multimeter in a long time. Maybe you’ve never used one! Lets go through the basic multimeter functions that you will need to understand to debug and repair most consumer electronics and household appliances.

Introduction

Typical multimeters can measure a number of different properties, including at a minumum voltage, current and resistance. Depending on the multimeter you have and its features you might also be able to measure temperature, capacitance, inductance, frequency and more.

Analog multimeters exist, but these days you are much more likely to come across digital multimeters.

Using a Multimeter

In general, to use a multimeter, you will set the dial depending on measurement type, and connect the probes to the multimeter ports and to your circuit.

The black probe always connected to the multimeter port labelled COM (common), while the red probe connects to either the VΩmA port or the 10ADC port (labels might be slightly different depending on the multimeter). For our purposes, we will almost always be using the VΩmA port, which is used for measuring voltage, resistance, and currents below 200mA, while the 10ADC port is only used for measuring higher currents.

For autoranging multimeters, each measurement type only has one setting on the dial. Many multimeters are non-autoranging though, meaning the measurement range is selected manually. The value on the dial is the maximum value that can be measured in that setting. For example, if the expected current is 25mA, then in the case below the dial should be set to 200mA.

Testing Continuity

One of the most useful functions of a multimeter when it comes to electronic repair is performing continuity checks. Continuity checks can test whether two components are electrically connected, which can help you to find shorts, loose wires, blown fuses, bad solder joins and more. Essentially, in a continuity check the multimeter measures resistance (see more below) and checks whether the resistance is below some threshhold (often ten ohms), in which case it will beep. Performing a continuity check:

  1. Switch the device off, unplug, remove batteries. (This check won’t work if there is current running through the circuit)
  2. Turn the dial to continuity mode
  3. Touch the multimeter probes to the circuit, in parallel with the suspected short / loose connection / blown fuse.
  4. The multimeter reading reports whether the probes are electrically connected (displays 0 and beeps) or disconnected (displays 1 or OL)

Note: To check continuity the multimeter passes a small amount of current through the circuit, which might damage very sensitive circuits. If in doubt, try using a different approach. 

Measuring DC Voltage

Measuring voltage can be useful to check the voltage of batteries and more. To measure voltage:

  1. Turn the dial to DC Voltage
  2. Touch the multimeter probes to the circuit – eg. to the two battery terminals.
  3. The multimeter reading reports the measured voltage.
Measuring Resistance

Measuring resistance is useful in a few different scenarios. If a solder join is cracked or wire is loose then a continuity check might pass, but the multimeter could measure some resistance. This would also be useful to check that resistance is within expected specifications, or to check that a diode is working properly (as discussed below).

To measure resistance:

  1. Turn the dial to resistance:
  2. Touch the multimeter probes to the circuit, in parallel with the resistor, or the section of the circuit to be measured.
  3.  The multimeter reports the measured resistance.

Note: To check continuity the multimeter passes a small amount of current through the circuit, which might damage very sensitive circuits. If in doubt, try using a different approach. 

Checking Capacitors

A common problem in broken electronics and appliances is burnt out capacitors. Capacitors store charges, so before you do anything else, ensure that the capacitor is discharged, or discharge it (see this safety post on how to discharge capacitors).

Then, to check capacitance:

  1. Turn the dial to Capacitance
  2. Touch multimeter probes across the capacitor
  3. The multimeter reports the measured capacitance

Some multimeters don’t have a capacitance setting. Not to worry, in that case, use the resistance setting to check whether the capacitor is behaving as expected:

  1. Turn the dial to Resistance
  2. Touch multimeter probes across the capacitor
  3. The multimeter will pass some current through the capacitor, which should gradually charge it. This means the multimeter reading should start at some low value and gradually increase, if the capacitor is working correctly. If there is a constant low value, that could indicate a short, while a constant high value, or OL, indicates an open capacitor. In both cases it would need to be replaced.
Checking Diodes

A multimeter can be used to check for a faulty diode (or LED) as follows:

  1. Turn the dial to diode mode.
  2. Touch the multimeter probes across the diode.
  3. The multimeter should display a voltage between 0.2 to 0.7 depending on the diode type.
  4. Switch the multimeter probes.
  5. The multimeter should read OL or 1.

This can also be done by setting the multimeter to check resistance and ensuring that it shows infinite resistance (open loop) in one direction, and a low resistance in the other direction.

Measuring DC Current

Measuring current using a multimeter is slightly more difficult, and often less useful than measuring resistance, voltage or continuity. These measurements are complicated by the fact that the multimeter needs to be connected to the circuit in series, so that the measured current passes through the multimeter. To measure current:

  1. Turn the dial to DC current
  2. Connect the multimeter to the circuit in series. This might be difficult if measuring an existing circuit, and might require some desoldering! If possible, use a different debugging strategy instead.
  3. The multimeter reading reports the measured current
AC Measurements

Household appliances and consumer electronics run on DC power. There should be no reason to use the AC measurement features of the multimeter! Things can also get more dangerous when it comes to measuring the AC power from wall outlets – there is no need to do this.

 

Mechanical Assembly – a quick introduction

We have several different kits of screwdrivers and Allan keys in our eKitchen equipment bags, but what are they all for?

> Emily’s mechanical assembly slides to be transcribed here!