Zachary Madin

Zachary Madin

he/him

Robotics PhD Student investigating collective dynamics with Bayesian inference in graph networks. I also work on embedded software, open source hardware projects and science communication.

Open to opportunities in robotics, software, and electronics.

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Pages

Posts

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portfolio

UoB SAT SOM Camera Adapter

A KiCAD PCB adapter bridging MIPI-CSI camera interfaces on a Variscite DART-MX8M SOM to FPC connectors for Xenics LWIR thermal cameras. Passive signal routing with a TXS0104EPWR level translator for the 3.3 V / 1.8 V I2C domain crossing.

UoBSAT SoM Interface Board

Carrier board for the University of Bristol satellite — hosts a Variscite DART-MX8M-PLUS SoM (NXP i.MX 8M Plus, quad-core A53 + 2.3 TOPS NPU) with redundant power OR, eFuse protection, GigE camera interface, and telemetry, in the Nanopower P31U CubeSat form factor.

Analogue Chaos Generator PCB

A KiCad PCB implementing four chaotic dynamical systems — Lorenz, Chua, Rössler and Duffing — entirely in analogue electronics, producing strange attractor patterns on an oscilloscope in X-Y mode. No microcontroller: the ODEs run as continuous-time physics in op-amp integrators and AD633 multipliers.

PROVE Pathfinder Main PCB

A hat for the SanCloud BeagleBone Enhanced on the PROVE Pathfinder satellite, handling power switching, current sensing, boot sequencing, and camera interfacing for a Basler and Tau thermal camera pair.

Microscope Camera Software — CM5 Linux Stack

A production-grade Linux application stack for a custom CM5 carrier board — Flask/gunicorn web server, live MJPEG streaming via picamera2, USB storage auto-mount, GPIO button handling, and WiFi management. Designed to behave like a finished product, not a prototype.

publications

Collective Anomaly Perception During Multi-Robot Patrol: Constrained Interactions Can Promote Accurate Consensus

Published in ACM/SIGAPP - Avila, Spain, 2024

We find that generally, MRP algorithms that promote physical mixing of robots, as measured by a higher connectivity of their emergent communication network, reach consensus more quickly.

Recommended citation: Madin, Zachary R and Lawry, Jonathan and Hunt, Edmund R, . (2024). "Collective Anomaly Perception During Multi-Robot Patrol." SAC 2024 1. 1(1). Paper link here.

Swift Trust in Mobile Ad Hoc Human-Robot Teams

Published in TAS - Austin, Texas, 2024

In designing robot systems with swift trust in mind, given the reliance on surface level cues such as robot appearance, it is also important to be aware of how different robot forms can influence expectations of capability.

Recommended citation: Sanja Milivojevic, Mehdi Sobhani, Nicola Webb, Zachary Madin, James Ward, Sagir Yusuf, Chris Baber, and Edmund R Hunt. 2024. Swift Trust in Mobile Ad Hoc Human-Robot Teams. In Proceedings of the Second International Symposium on Trustworthy Autonomous Systems (TAS '24). Association for Computing Machinery, New York, NY, USA, Article 16, 1–10. https://doi.org/10.1145/3686038.3686057 Paper link here.

Co-movement and trust development in human-robot teams

Published in ICSR - Odense, Denmark, 2024

Qualitative interviews with participants confirmed that robot proximity was a decisive factor in which robot they preferred to call, and that a robot staying nearby over time made it “part of the team”.

Recommended citation: Webb, N., Milivojevic, S., Sobhani, M., Madin, Z. R., Ward, J. C., Yusuf, S., ... & Hunt, E. R. (2024, October). Co-movement and trust development in human-robot teams. In International Conference on Social Robotics (pp. 107-120). Singapore: Springer Nature Singapore. Paper link here.

repair

Audio Amplifier

Repair No. , 1900

Problem:    USB connector not connecting 
Solution:   Re-solder connector 
Brand:  Generic 
Cost new:   ??? 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

Bluetooth amplifier wouldn’t accept a charge from the USB cable, when looking closer the micro-usb connector had been bent off, and pulled a bunch of the traces with it off the PCB! Managed to re-heat the connector and push it down to make a connection again, and then plopped some epoxy over the back of the connector to take some of the strain out.

MacBook water ingress

Repair No. , 1900

Problem:    Water damage 
Solution:   Replace FPC connector 
Brand:  Apple 
Cost new:   £800 
Cost of fix:    £4 
Age:    TODO 
Success?:   Yes

Water got spilled on a friend’s laptop, and would turn on but the screen didn’t show anything. Taking it apart showed the connection from the mobo to the screen had a short and melted and damaged the screen connector. The whole connector would have to be replaced, which I’m going to do once I source the right component and reset the laptop.

Marshall Bluetooth Headphones

Repair No. , 1900

Problem:    No Bluetooth 
Solution:   Replace battery and NTC 
Brand:  Marshall 
Cost new:   ??? 
Cost of fix:    £12.00 
Age:    TODO 
Success?:   Yes

Pair of Marshall wireless headphones that would work if you plugged an audio source into the 3.5mm audio jack, but wouldn’t boot and accept a bluetooth connection. Opened them up, and the battery was entirely dead! Sourced a replacement that would fit inside the headphones, but they didn’t come with an NTC resistor like the original battery. Bought a replacement NTC and put that in a suitable position and it all works fine! The standard NTC for this battery was a 10kR, but it’s worth checking with the original as if you choose the wrong ranged resistor, the onboard micro might consider it as a fault!

PA Kit

Repair No. , 1900

Problem:    Went bang! 
Solution:   Replace drivers and board components 
Brand:  QTX Sound 
Cost new:   £600.00 
Cost of fix:    £118.28 
Age:    TODO 
Success?:   Yes

Guys came in with a PA set that had been plugged in when the bassist incorrectly wired up one of their pedals/amplifiers, then there was an awful sound and a disgusting smell, according to them. Had a cursory look at the PA deck, to make sure nothing was wrong there and didn’t see anything immediately broken. Open the speaker cabs and look at the pre-filters and the 20W resistor as part of the RLC filter had gotten so hot the legs had exploded out of both speakers! The thermal fuse on both boards inside the speakers had exploded and released their magic smoke. One of the cones sounded pretty damaged, my rubric for that being if you push in on one of the cones and hear a ‘crinkly’ sound, like a crisp packet being rustled, the driver is damaged. One speaker cone sounded exactly like that, and the other one sounded similar bit not as bad. I asked the people who brought them in, and they were happy to replace both of them at the same time so they’d sound close to similar. A colleague contacted the speaker manufacturer and suggested a replacement driver, so sourced that. Then purchased replacement components for the board and re-soldered the new ones on – sourced from https://willys-hifi.com which was a great site for this. Nice and easy fix, if a little expensive for the customers.

Portable Projector – Dead Battery

Repair No. , 1900

Problem:    Dead battery 
Solution:   No Fix 
Brand:  Harmon Kardon 
Cost new:   £300 
Cost of fix:    0p 
Age:    TODO 
Success?:   No

This projector came in that wouldn’t boot at all. It’s a portable mini projector, but no buttons would do anything and wouldn’t work. Started to disassemble, and checked the battery which was totally dead! You can’t get replacements for this battery because it’s got to be a specific size in order to fit inside the container. Unfortunate very expensive and sophisticated bit of kit all to end up as junk because you can’t get a replacement battery, and you can’t run it by having it plugged in!

Arcam_A38_Amplifier

Repair No. , 1900

Problem:    Current source failure, transformer failure caused by regulator
Solution:   Lots of work, replace transformer, regulator, transistors and passives
Brand: Arcam
Cost new:   £1450
Cost of fix: £30
Age: 15
Success?:   Yes

What a mammoth repair! This amplifier came into the repair cafe and was a piece of art in terms of the layout of the board!

Cat Electronic Feeder

Repair No. , 1900

Problem:    Dead microcontroller
Solution:   N/A
Brand:
Cost new:   £150
Cost of fix:0
Age:
Success?:   No

XBOX_hdmi_chip

Repair No. , 1900

Problem:    HDMI chip failure
Solution:   Replace HDMI chip
Brand:
Cost new:   £150
Cost of fix:£11
Age:
Success?:   Yes

Waterlogged weighing scale

Repair No. , 1900

Problem:    Water getting to the PCB and corroding wires
Solution:   Clean PCB and re-solder wires
Brand:
Cost new:   £20
Cost of fix:0
Age:
Success?:   Yes

Please descale espresso baskets!

Repair No. , 1900

Problem:    Clogged espresso machine
Solution:   De-scale espresso basekt & clean
Brand:
Cost new:   £240
Cost of fix:0
Age:
Success?:   Yes

Kettle Contacts

Repair No. , 1900

Problem:    Kettle contacts tarnished
Solution:   Brillo pad and contact cleaner on contacts
Brand:
Cost new:   £30
Cost of fix:0
Age:
Success?:   Yes

Rear bike light - dynamo

Repair No. , 1900

Problem:    Wire had snapped off
Solution:   Re-solder wire
Brand:
Cost new:   40
Cost of fix:0
Age:
Success?:   Yes

Bang-polar Junction Transistor

Repair No. , 1900

Problem:    Exploded BJT converted to dust 
Solution:   Replace BJT and board 
Brand:  Unknown 
Cost new:   £20.00 
Cost of fix:    10p 
Age:    TODO 
Success?:   Yes

A magnification and combined lamp wouldn’t turn on the lights found in the recycling bin. Taking it apart there’s a simple potentiometer that controls the current to the LEDs via a BJT that had exploded and taken the PCB with it. Jury-rigged a simple circuit on perfboard that connects to the potentiometer that achieves the same thing. It is now my desk magnification for when I need something extra!

Microwave

Repair No. , 1900

Problem:    Won’t produce heat 
Solution:   Scrap 
Brand:  Generic 
Cost new:   ??? 
Cost of fix:    0p 
Age:    TODO 
Success?:   No

Don’t usually look at microwaves, but thought it might be an easy fix of a dodgy connector, as the screen would turn on and you could change dials and settings, but didn’t actually ‘go’ and start powering the microwave. I thought it would be an issue from the push buttons not making a good connection, but they all worked properly. Unfortuantely probably something with the electronic portal to hell that heats the food. Into the scrap it went, but we kept the control board to salvage components as and when we need them.

Ultra 1968 Vinyl Player

Repair No. , 1900

Problem:    Terrible sound quality 
Solution:   New pre-amplifier transistor 
Brand:  Ultra 
Cost new:   ??? 
Cost of fix:    10p 
Age:    TODO 
Success?:   Yes

TODO

Blender blended bearings

Repair No. , 1900

Problem:    Blitzed bearings
Solution:   N/A
Brand:
Cost new:   £90
Cost of fix:0
Age:
Success?:   No

Disconnected supply grinder!

Repair No. , 1900

Problem:    A wire had snapped off!
Solution:   Re-solder wire
Brand:
Cost new:   £60
Cost of fix:0
Age:
Success?:   Yes

Mangled USB port

Repair No. , 1900

Problem:    Mangled USB port to be replaced
Solution:   Solder in new USB port
Brand:
Cost new:   £50
Cost of fix:50
Age:
Success?:   Yes

Exploded dishwasher triac

Repair No. , 1900

Problem:    Exploded triac
Solution:   Replace triac
Brand:
Cost new:   £280
Cost of fix:120
Age:
Success?:   Yes

KitchenAid mixer at full speed

Repair No. , 1900

Problem:    Mixer kept running at full speed
Solution:   Replace out startup capacitor (had shorted)
Brand:
Cost new:   £180
Cost of fix:0
Age:
Success?:   Yes

Explosive microcontroller??

Repair No. , 1900

Problem:    Microcontroller exploded somehow?
Solution:   No fix
Brand:
Cost new:   £70
Cost of fix:0
Age:
Success?:   No

PS5 vibration not working

Repair No. , 1900

Problem:    Rumble feature not working
Solution:   Re-solder motor to PCB
Brand:
Cost new:   £50
Cost of fix:0
Age:
Success?:   Yes

Magnifier Light

Repair No. , 1900

Problem:    Would not turn on (dead transistor) 
Solution:   Replace transistor and board 
Brand:  Unknown 
Cost new:   ??? 
Cost of fix:    80p 
Age:    20yrs+ 
Success?:   Yes

This was something found in the recycling bin that I thought we could use. A DC powered magnifier and light. Opening it up revealed an absolutely catastrophic death of some poor transistor that had turned to DUST!. I removed the board as it had cracked in half as well. Replaced the circuit with something on stripboard to have an adjustable current source to drive the LEDs. It is now used in our cafe to repair other things!

Microphone Screen dodgy

Repair No. , 1900

Problem:    Lines on screen 
Solution:   Clean connector 
Brand:  TODO 
Cost new:   ??? 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

Device works fine in terms of recording audio and turning on, but there are a series of lines on the screen that don’t disappear and never turn on. Open it up, and the ribbon cable connection from the screen to the mainboard was old and slightly corroded and making a bad connection. Used a bit of switch cleaner and a Q-Tip to clean up the connector and the issue disappeared!

Slow cooker

Repair No. , 1900

Problem:    Wouldn't turn on or heat up 
Solution:   Reset thermal fuse 
Brand:  Unknown 
Cost new:   £250 
Cost of fix:    0p 
Age:    2yrs 
Success?:   Yes

This was quite a fun one that I did, as it wasn't working and all and wouldn't turn on. Usually with these things it's a thermal fuse that dies, so checked those, and no issue there. After pondering, and other volunteers pondering I left it for a while. Then another volunteer who took over found that there's a dedicated resettable thermal fuse that you have to press down to reset! This was written nowhere in the manual though!!!!

Bike light - disconnected cables

Repair No. , 1900

Problem:    Internal cables disconnected
Solution:   Re-solder cables to PCB
Brand:
Cost new:   £30
Cost of fix:£0
Age:
Success?:   Yes

Please descale your appliances :(

Repair No. , 1900

Problem:    Exploded boiler unit due to scale
Solution:   De-scale boiler and re-apply sealant
Brand:
Cost new:   £150
Cost of fix:£11
Age:
Success?:   Yes

Exploded capacitor CD player

Repair No. , 1900

Problem:    Kerblammed capacitor
Solution:   No fix
Brand:
Cost new:   £80
Cost of fix:0
Age:
Success?:   No

Kettle temperature switch

Repair No. , 1900

Problem:    Snapped plastic in switch
Solution:   Superglue and activator on broken plastic
Brand:
Cost new:   £40
Cost of fix:0
Age:
Success?:   Yes

Dodgy Screen on Voice Recorder

Repair No. , 1900

Problem:    Screen connector was dirty
Solution:   Clean connector with contact cleaner and fibre brush
Brand:
Cost new:   £80
Cost of fix:£0
Age: 12 years
Success?:   Yes

Strimmer motor disconnected

Repair No. , 1900

Problem:    Motor wire disconnected
Solution:   Resolder motor wire
Brand:
Cost new:   £80
Cost of fix:0
Age:
Success?:   Yes

Lamp

Repair No. , 1900

Problem:    Not turning on 
Solution:   Re-solder connections 
Brand:  Generic 
Cost new:   £20 
Cost of fix:    0p 
Age:    1yr 
Success?:   Yes

Nice and easy fix, disassemble and re-solder wire that had snapped!

Mazzer Burrs

Repair No. , 1900

Problem:    Burrs hadn't been used for a while and collected moisture and started to rust 
Solution:   "Rust remover, scrubbing, washing, and coating in coffee oils" 
Brand:  Mazzer 
Cost new:   £50 
Cost of fix:    5p 
Age:    4yrs 
Success?:   Yes

I got a new Mazzer Super Jolly grinder and it's one of the projects I'm doing to refurbish it up in the way I want to. Part of that included doing up the burrs as they had accumulated a bunch of rust and were dirty. Because they will grind the beans I didn't want rust on them. Used some rust remover and plenty of scrubbing with a nylon brush and some wire wool cleaned it up after a bunch of passes. Washed off the remaining rust remover with water, then popped them in the oven at a very low temp to make sure there was no remaining moisture on them. Then I ground a whole bag of cheap beans to a very fine grind to get them covered in some bean oils to protect the surface.

Gunky bearing

Repair No. , 1900

Problem:    Wouldn't spin 
Solution:   Clean main bearing 
Brand:  Bosch 
Cost new:   £75 
Cost of fix:    0p 
Age:    3yrs 
Success?:   Yes

The main bearing for the rotor had siezed up from too much dust entering it! Tried to press off the bearing to see if we could replace it, but was not budging. Method instead was to flood the bearing and twist it by hand to crush the dust and muck inside the bearing, and keep flooding it with oil so that the detritus leaked out of the bearing. With enough spinning and oil it ended up clean enough and worked happily. Extended the life a bit more of this sander!

Bosch Athlet Battery Board

Repair No. , 1900

Problem:    Batteries fully drained, short on control board
Solution:   New batteries, replace diode on board
Brand:
Cost new:   £120
Cost of fix:£22
Age:
Success?:   Yes

Electronic toothbrush wires

Repair No. , 1900

Problem:    Charging wire had become disconnected
Solution:   Reconnect charging wire
Brand:
Cost new:   £80
Cost of fix:0
Age:
Success?:   Yes

Infernal Coffee machine

Repair No. , 1900

Problem:    MYSTERY 
Solution:   ALSO MYSTERY 
Brand:  Jura 
Cost new:   £1250 
Cost of fix:    0p 
Age:    0p 
Success?:   Yes

Coffee machine that came in from one of the stalls in sparks that would have an error during the boot up sequence. It would give some error code on the screen that didn’t describe much and Google searching came up with no information! I could hear a relay engaging before it switched off, so there must be some software deciding to turn itself off, so I figured that the code was successfully executing but some status during the bootup sequence was bad and engaged some safety process. I spent the end of many sessions trying to get into this thing, and then diagnosing it. Both of the control boards were fine, no visible issues that screamed error. Started unplugging cables that went to the control board to see which one triggered the fail state, and eventually found a 2-cable connector that would cause it to fail the boot process. When I unplugged it, it was able to get past that auto shut off, but then returned an error later in the boot process saying that something was disconnected. Followed that cable and it lead to a pressure sensor of sorts that wasn’t well connected, so I think it just wasn’t making electrical contact! Re-connected it and reassembled the machine, and then got to enjoy a cup of coffee from the machine. Very satisfying cup of coffee!

Mangled Cable – Scooter

Repair No. , 1900

Problem:    Exploded PCB from cable being crushed 
Solution:   No Fix 
Brand:  Halfords 
Cost new:   £90 
Cost of fix:    0p 
Age:    TODO 
Success?:   No

Scooter came in, it wouldn’t turn on at all and the electric motor wouldn’t spin. Taking it apart, when looking at the PCB there was a very obvious track that had gotten so hot it de-laminated itself and burnt the copper track such that it was an open circuit! When taking it further apart, what had happened was the control and power cables that go up to the control module, had been crushed in a pinch point in the scooter stem, causing a GPIO line to the microcontroller to get a whopping 24V! This was the GPIO line that measures the throttle, so once I’d sorted and fixed the cable, even though it would turn on, and the micro would do something (send signals to the gate drivers), the GPIO pin on the micro was toast, and the entire thing would have to be replaced. As the code to flash the micro is unavailable, it is essentially un-fixable. I looked online for suitable brushless motor controllers at 24V, but couldn’t find one that would fit the requirements for the scooter. Unfortunately, the whole electric portion of this scooter is now broken. It still functions as a scooter though!

Kobo Reader Leak

Repair No. , 1900

Problem:    Water damage 
Solution:   Scrap 
Brand:  Kobo 
Cost new:   ??? 
Cost of fix:    0p 
Age:    TODO 
Success?:   No

E-reader had a bit of moisture ingress from something being spilled on it. Opened it up and there was a bunch of backlight LEDs that had shorted and exploded, which meant that the LED power rail had been ruined. Removed the offending LEDs and followed the rail back to the source, but still wouldn’t generate the voltage required. Followed the connection from the LED to a chip that controls the screen matrix, and there’s some issue there, but there is no documentation available for that chip, so it’s basically a dead end at that point. The parts did not go to waste however! The battery has gone towards a project I’m working on that needed a nice flat battery!

Dodgy Strimmer Connection

Repair No. , 1900

Problem:    Snapped connection on motor 
Solution:   Re-solder power cable 
Brand:  Generic 
Cost new:   ??? 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

Electric strimmer wouldn’t turn on and move, but all the connections from the plug to the cables seemed fine. Turns out inside the little choke before the motor connection, under the heatshrink, the spool of wire had been twisted too much and needed re-soldering. Nice and simple fix once the issue had been found!

CD Player Tray

Repair No. , 1900

Problem:    CD player would not play 
Solution:   Replace belt and lubricate mechanism 
Brand:  Denon 
Cost new:   £150 
Cost of fix:    0p 
Age:    5yrs 
Success?:   Yes

"Customer brought in a CD player that wouldn't play a CD and would just keep sticking. It would open and receive a CD, but then would get stuck on track 1 and never play. Turns out running the mechanism with the shell off revealed that the tilt mechanism to engage the motor wasn't being activated properly. The belt that had the job to activate the mechanism to tilt was just spinning in place and never being activated. Replaced the belt with a suitable one and added some drops of oil on the plastic parts that wipe together and it loads and plays CDs correctly!"

Coffee Grinder Not Grinding

Repair No. , 1900

Problem:    Grinder would not turn on 
Solution:   Re-solder connection 
Brand:  Generic 
Cost new:   £60 
Cost of fix:    0p 
Age:    2yrs 
Success?:   Yes

"Coffee grinder came in that just suddenly stopped working one day. Opening it up didn't make much sense as all the components looked fine. Trying to follow the connections to the motor revealed that one of the terminals of the motor wasn't connected. Upon closer inspection the wire connection had somehow snapped!"

Dodgy Charger Port

Repair No. , 1900

Problem:    Won't charge unless held in position 
Solution:   Replace charging port 
Brand:  Lenovo 
Cost new:   £450 
Cost of fix:    £12 
Age:    4yrs 
Success?:   Yes

Customer brought this in who didn't have the funds to take it to a repair shop so we replaced the charging port for them if they paid for the parts. The issue was the connector in there relies on a piece of sprung metal to make a connection with the terminals. This over time had snapped and now only made a contact if you forced the charger into the socket, so less than ideal. Purchased a port component and soldered it at home where I had my high powered soldering iron as it required quite a bit of heat to flood the many layers in the motherboard! Often for a job like this if I don't care about the component I'm removing, I'll destroy/disassemble it in place so that less heat is being removed from my iron, so the remaining parts are smaller and require less heat to remove and I'm thus less likely to damage the board from heat. Soldered the new one in place and happily charges now.

Torpedo timer (Yes that cool)

Repair No. , 1900

Problem:    Wouldn't wind up 
Solution:   Forward to watch maker contact 
Brand:  Robert North and Sons 
Cost new:   N/A 
Cost of fix:    0p 
Age:    ~75 years 
Success?:   No

Well this was an incredible first. A torpedo clock timer from the second world war!! Somebody brought this is because they wanted help figuring out why it didn't work, and how to fix it. This was by far the coolest thing to come into the cafe! The issue in the end is that one of the gears for winding up the coil had been damaged and the teeth were stripped off the gearface. We have a volunteer that knows somebody who manufactures custom gears for precisely this kind of application so we passed on their number and wished them the best.

Holy Grail Reverb Dead EEPROM

Repair No. , 1900

Problem:    EEPROM is dead and won't boot
Solution:   No fix
Brand:
Cost new:   110
Cost of fix:0
Age:
Success?:   No

Strimmer Cables

Repair No. , 1900

Problem:    Wire disconnected
Solution:   Re-connect and crimp wire
Brand:
Cost new:   £60
Cost of fix:0
Age:
Success?:   Yes

Portable Coffee Grinder

Repair No. , 1900

Problem:    Motor wouldn’t move grinder 
Solution:   Insert missing circlip 
Brand:  UFIT 
Cost new:   £25.00 
Cost of fix:    1p 
Age:    TODO 
Success?:   Yes

Grinder was donated in the junk box, that would hold a charge and you could hear the motor spin, but the actual grinder mechanism wouldn’t engage. Open the device up and one of the circlips that holds the attachment in place had snapped or come loose, and now the thing was fixed for the cost of a 1p circlip! One of our volunteers is using it to grind up egg shells to make egg shell porcelain with!

Coffee Switch

Repair No. , 1900

Problem:    Button won't work 
Solution:   Glue flexible plastic 
Brand:  Generic 
Cost new:   £45 
Cost of fix:    0p 
Age:    3ys 
Success?:   Yes

We have had three of these into the cafe, all with the exact same problem. They use a piece of plastic to act as the spring for the on button, which over the lifetime snaps and breaks. Thus the button becomes stuck and does not activate. The solution we have found works well is to use some hard plastic that flexes a bit and glue or drill it into a support structure.

Hand(le) off my guitar!

Repair No. , 1900

Problem:    Handle came off 
Solution:   Braided steel wire with rivets 
Brand:  Generic 
Cost new:   £60 
Cost of fix:    20p 
Age:    15 yrs 
Success?:   Yes

Somebody brought in a guitar case that the handle came off, that they were having issues trying to reattach. We agreed that a good solution that would still allow the handle to 'swing' would be to thread braided steel wire and rivet the wire in place through the body. This involved peeling back the fabric lining to expose the mounting holes, then feeding the wire through and then riveting the pieces in place in the hole. Definitely not going anywhere, so a safe guitar!"

Kids Electric Car

Repair No. , 1900

Problem:    Dead battery, won't drive 
Solution:   "Replace battery, replace momentary switch" 
Brand:  Range Rover 
Cost new:   £160 
Cost of fix:    £2.50 
Age:    Unkown 
Success?:   Yes

Customer came in with a kids electric car that wouldn't drive due to a dead battery. They brought in a battery to replace which I inserted, but it still woudln't drive! Worked backwards from the motor, which worked, and found that the accelerator pedal is a momentary KCD4 switch that wasn't making the correct connection. After a bunch of attempts to fix the existing switch, I opted for buying a brand new one. Soldered in it and reassembled and had one happy small child!

PARTY

Repair No. , 1900

Problem:    Won't turn on 
Solution:   Replace transistor 
Brand:  Generic 
Cost new:   £40 
Cost of fix:    60p 
Age:    3yrs 
Success?:   Yes

Annoyingly I don't have a photo of the original transistor that met a grisly end. Neon party light that had the transistor that exploded dramatically. Was a nice and easy fix to get one from our generic parts drawer, and solder it in and works like new!

More Roberts Radios!

Repair No. , 1900

Problem:    "Won't boot; dead buck controller" 
Solution:   Replace buck with LDO with enable 
Brand:  Roberts 
Cost new:   £80 
Cost of fix:    £3.50 
Age:    5yrs	 
Success?:   Yes

At this point I have fixed three Roberts radios so I'm somewhat the expert. Customer brought this in and wouldn't boot or show anything on the screen. Found the schematics and the service manual that gives you a flow chart to diagnose and look for voltages. One of the main supply voltages after the power in wasn't being produced! There should be a 5.3V rail being generated, but it wasn't present at all. That rail is generated by a buck controller that was sending a constant voltage to a MOSFET, so the controller was obviously dead. I tried looking for replacement parts for that controller in the same package, but to no avail. They use bucks for efficiency as this radio is able to run from batteries, but I'm not fussed about efficiencies for repairs like this. I found a suitable 5.3V LDO that I had kicking around that also has an enable pin. Wired up my little abomination with enamalled wire and hey presto! Working radio!! I think there's still an issue with something on the LCD screen as the contrast isn't that high. It's getting the necessary power, but there are supposed to be some configuration resistors but I couldn't find a datasheet for the LCD so that's as far as I was willing to go for that.

Boom box new belts

Repair No. , 1900

Problem:    Belts on the tape player failed
Solution:   New tape player belts
Brand:
Cost new:   £80
Cost of fix:£0.1
Age:
Success?:   Yes

Bose Wave CD Player

Repair No. , 1900

Problem:    Failed IC
Solution:   N/A
Brand:
Cost new:   £90
Cost of fix:0
Age:
Success?:   No

Kinked Kable Kaused Kaput

Repair No. , 1900

Problem:    Wire getting twisted and shorting
Solution:   Re-attach wire
Brand:
Cost new:   £90
Cost of fix:0
Age:
Success?:   Yes

Ryobi Multi-Tool

Repair No. , 1900

Problem:    No longer spinning
Solution:   New trigger mechanism
Brand:
Cost new:   £80
Cost of fix:£22
Age:
Success?:   Yes

Squished wire in plug

Repair No. , 1900

Problem:    Squished wire causing resistance
Solution:   Re-fit plug head
Brand:
Cost new:   £5
Cost of fix:0
Age:
Success?:   Yes

Shredded gears with your ebike_motor sir?

Repair No. , 1900

Problem:    Shredded planetary gears 
Solution:   Replace gearbox and bearings  
Brand:  Unbranded 
Cost new:   £800 
Cost of fix:    £25.00 
Age:    TODO 
Success?:   Yes

Black Magic Smoke Machine

Repair No. , 1900

Problem:    Bang 
Solution:   Scrap 
Brand:  Generic 
Cost new:   £15.00 
Cost of fix:    0p 
Age:    TODO 
Success?:   No

Only including this because it was kind of funny. Somebody brought in this power adapter as it no longer worked, and when I handled it I could hear something rattling. Opened up the case and immediately saw the issue! Multiple components had exploded and were specks of dust in the case. Not worth repairing something this cheap and this destroyed, but fun to see what happens when the magic pixies don’t cooperate.

Roberts Radio Switch

Repair No. , 1900

Problem:    Won’t switch FM/DAB Mode 
Solution:   Replace tactile switch 
Brand:  Roberts 
Cost new:   £110.00 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

Somebody brought this radio in that would turn on, but the ability to switch between FM and DAB mode wouldn’t work. Taking it apart, it was just a small tactile switch that had maxed out the lifecycle. We had another sacrificial Roberts Radio that I could salvage the switch from, and worked very happily after that. Was a bit of a pain to get at the thing however!

Akai Turntable

Repair No. , 1900

Problem:    Can't sync direct drive  
Solution:   Switch cleaner on potentiometers 
Brand:  Akai 
Cost new:   £300+ 
Cost of fix:    0p + £20 
Age:    Unknown 
Success?:   Yes

This was a turntable that was found in the recycling bin, which we thought must be able to be fixed. Powers on, but as it's a direct drive turntable, you need to ensure the marks on the disc are synchronised with the pulsed light. These are controlled by the trimming potentiometers, which no matter how much you spinned them they didn't seem to synchronise. Opened the unit and squirted a bunch of switch cleaner into the potentiometers and there we go! When we put a record on however, we realised the stylus had been terribly abused and is missing the sharp diamond point. A new stylus is on order for £20 and we are seeing what we can do about the counterweight. This will go on to be sold at the cafe to keep our funds going.

Hair Straighteners

Repair No. , 1900

Problem:    Intermittently turning off 
Solution:   Re-solder wire connection 
Brand:  Unknown 
Cost new:   £160 
Cost of fix:    0p 
Age:    8 yrs 
Success?:   Yes

Customer brought this in, and she had the issue that when you would turn it on and use it, they would suddenly turn off! Opened them up and found that one of the main power connections to the heating element had snapped due to movement. Re-solder it and crimp it down and it works happily. One interesting note about these straighteners is that they do not have a sensor feedback to detect temperature that I could spot, so they must work on calibrated heat elements and some form of current control with a known power loss. Quite clever design inside too.

Kindle

Repair No. , 1900

Problem:    Stuck on screen 
Solution:   Send to Amazon for voucher off new kindle. Dead battery 
Brand:  Amazon Kindle 
Cost new:   £80 
Cost of fix:    0p 
Age:    5 yrs 
Success?:   No

Customer brought in this Kindle that was stuck on the last page she read, and wouldn't charge at all. Opened it and measured the battery voltage which should have been 4.2V, when charging it would tick up but the second you removed the charging port the voltage would instantly drop back down. It is possible to buy replacement batteries for Kindles, but Amazon also runs a scheme where you can trade in kindles for vouchers and money off a new kindle so that's what the customer did, as it was an old model anyway.

Koala Light

Repair No. , 1900

Problem:    Won't turn on 
Solution:   "Dead battery, re-wire to be plug powered only" 
Brand:  Generic 
Cost new:   £15 
Cost of fix:    0p 
Age:    Unknown 
Success?:   Yes

This was an item that had been chucked into recycling that looked far too cute to bin. The issue was the cheap lithium battery had died, and the lights required it to function at all. I removed the battery and bypassed the charging circuit so that the LEDs run purely on a USB power supply. Family member is now the happy owner of this cute night light.

Amplifier Connector Fuzz

Repair No. , 1900

Problem:    Lots of noise on left speaker channel
Solution:   Solder new photo jack
Brand:
Cost new:   £350
Cost of fix:90
Age:
Success?:   Yes

Failed Battery pack for Vacuum

Repair No. , 1900

Problem:    Dead batteries
Solution:   New batteries
Brand:
Cost new:   £90
Cost of fix:£16
Age:
Success?:   Yes

Canon camera lens

Repair No. , 1900

Problem:    Stuck lens mechanism
Solution:   Tiny dab of thin oil
Brand:
Cost new:   £50
Cost of fix:0
Age:
Success?:   Yes

Dehumidifier upside down board

Repair No. , 1900

Problem:    Sensor to detect sideways was disconnected
Solution:   Re-solder sensor wires
Brand:
Cost new:   £110
Cost of fix:0
Age:
Success?:   Yes

Pop goes the capacitor

Repair No. , 1900

Problem:    Exploded capacitor
Solution:   Junk it
Brand:
Cost new:   110
Cost of fix:0
Age:
Success?:   No

Violently exploded rotor

Repair No. , 1900

Problem:    BANG
Solution:   Junk
Brand:
Cost new:   £150
Cost of fix:0
Age:
Success?:   No

Sage toaster control board

Repair No. , 1900

Problem:    IC had blown on control board
Solution:   Can't replace IC!
Brand: Sage
Cost new:   £120
Cost of fix:0
Age: 9 years
Success?:   No

Sewing machine capacitor

Repair No. , 1900

Problem:    Shorted capacitor
Solution:   New capacitor
Brand:
Cost new:   £250
Cost of fix:0
Age:
Success?:   Yes

Air Fryer

Repair No. , 1900

Problem:    Dead thermal fuse 
Solution:   Replace thermal fuse 
Brand:  Generic 
Cost new:   £60.00 
Cost of fix:    20p 
Age:    TODO 
Success?:   Yes

Air fryer came in not working at all, 99 times out of 100 with things like this it’s going to be the thermal fuse. The issue is taking the sodding thing apart! Very much not designed to be serviced / fixed considering the fix is a 20p thermal fuse that needs to be replaced…

Roberts Radio Voltage

Repair No. , 1900

Problem:    Screen won’t turn on 
Solution:   "Removed the buck converter,  replace with an LDO" 
Brand:  Roberts 
Cost new:   £120.00 
Cost of fix:    ~15p 
Age:    TODO 
Success?:   Yes

This was a marathon! I don’t usually spend so long on repairs, but a customer came in with a radio that was very sentimental to them, as a family member had bought it for them and they loved it dearly. I spent a long time looking at what was wrong with it. For a lot of the Roberts Radio line they provide schematics, service manual and block diagram! I was very impressed with the amount of information they give. Unfortunately, this model didn’t give you any of that… So I had to analyse the circuit on the board and figure out what things should be doing, and then figure out whether what they are currently doing are as designed. I came to the conclusion eventually that one of the supply rails for the microcontroller and radio receiver, was only receiving 3.21V, which when I first spotted that assumed it would be ‘enough’ for the necessary components to use. The add-on board that manages the radio and audio processing was a black box, no documentation or datasheets anywhere to be found. I deduced that it needed a 1.2V rail, as well as a 3.3V rail. I isolated the device that was generating the 3.3V by removing a diode in the buck converter, and then added a 3.3V supply from my bench top directly into that pad to see if that was the issue, and lo and behold, it works!! Then I just had to figure out how best to do this inside the device so that I could reassemble it. As ugly as it ended up being, I replaced the buck converter with an LDO providing 3.3V, as I could find the corresponding SMD pads to match when I soldered the LDO in a specific pattern. They use buck converters for this as it’s more efficient and as you run these devices from batteries, you want them as efficient as possible, but I figured it wasn’t a huge loss by contributing to a net negative in effficiency for the device… Reassembled the radio and got a very happy customer.

Marantz Amplifier

Repair No. , 1900

Problem:    TODO 
Solution:   TODO 
Brand:  Marantz 
Cost new:   TODO 
Cost of fix:    TODO 
Age:    TODO 
Success?:   TODO

TODO

Dead Charger Shaver

Repair No. , 1900

Problem:    Dead charging circuit 
Solution:   Scrapped for parts 
Brand:  Phillips 
Cost new:   £60 
Cost of fix:    0p 
Age:    1yr 
Success?:   No

Somebody brought this shaver in as it wasn't charging or working at all. Taking it apart reveals a battery that is dead, but the charging circuit was also dead! No volts provided to the battery by the charging cirucit when plugged in. No schematics available so impossible to fix.

Xbox One HDMI

Repair No. , 1900

Problem:    No HDMI signal received 
Solution:   Replace HDMI chip on motherboard 
Brand:  XBOX 
Cost new:   £100 
Cost of fix:    £5.15 
Age:    UnknPAown 
Success?:   Yes

Another volunteer said that they had come across a similar issue with xbox ones at another repair cafe, so this was nice and easy to diagnose! No HDMI signal on the output, but it boots up and displays the necessary lights. Identified the required HDMI timing IC and bought one (SN75DP159RSBR). Removed the old chip with my rework station and soldered the new chip on. Jobs a goodun!

Sewing machine capacitor!

Repair No. , 1900

Problem:    Full speed sewing machine
Solution:   Replace capacitor
Brand:
Cost new:   £150
Cost of fix:0
Age:
Success?:   Yes

Bad IMU Production

Repair No. , 1900

Problem:    Shorted connection on IMU 
Solution:   Remove excess solder 
Brand:  DFRobot 
Cost new:   £75 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

This is an issue I had during PhD, where we’d purchased a few IMUs at once and one of them just wouldn’t boot and wouldn’t turn on. I couldn’t resist opening it up and having a look at what the issue was. Turns out the IMU chip itself had an issue during soldering, causing 3.3V to be shorted to ground, as you can see in the photos. This was quite surprising, as if 3.3V was shorted, it wouldn’t have been possible to flash the devices in the factory with the microcontroller code? The corresponding microcontroller is powered by 3.3V, so it needed that rail to be correct. The manufacturers obviously didn’t have a check to see if the micros were successfully flashed! We got a full refund once we showed these images

Camera Lens Stuck

Repair No. , 1900

Problem:    Lens stuck opening 
Solution:   Bit of oil on mechanism 
Brand:  Canon 
Cost new:   ~£50 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

Camera came in that had issue automatically opening the lens covers when booting. Disassemble and very precisely add a tiny dab of oil on the mechanism that releases/retracts the covers. Cycle the camera a few times and now the mechanism opens happily. Pretty sure a collection of dust and nasty stuff gunked up the mechanism

Til’ the wheels come off

Repair No. , 1900

Problem:    Wheel kept slipping off a trolley 
Solution:   Widen diameter of axle 
Brand:  Generic 
Cost new:   ??? 
Cost of fix:    2p 
Age:    TODO 
Success?:   Yes

The wheel of a pull trolley kept falling off. Disassembling the mount, the plastic that holds the wheel on had lost the bend that it needs to hold the wheel on. I wrapped a load of teflon plumber’s tape around the axle to thicken it, and then forced the wheel over the bump so that it won’t come off again. Happy quick fix

Sony Walkman

Repair No. , 1900

Problem:    Intermittent audio connection 
Solution:   Get a replacement 3.5mm  
Brand:  Sony 
Cost new:   ??? 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

The audio jack would only work if you pressed the audio jack in at a certain angle, so this was an obvious fix. Re-solder the connector and make sure it is making a good connection and not likely to pry off again.

Water Fountain Leakage

Repair No. , 1900

Problem:    Water leaked into PCB
Solution:   Replace components
Brand: N/A
Cost new:   £45
Cost of fix:£4
Age:
Success?:   Yes

Curse upon Krups engineer!

Repair No. , 1900

Problem:    Broken switch plastic!!!
Solution:   New plastic
Brand:
Cost new:   £50
Cost of fix:0
Age:
Success?:   Yes

Beautiful headphone design

Repair No. , 1900

Problem:    Attach new cable
Solution:   Solder in new cable
Brand:
Cost new:   £110
Cost of fix:£12
Age:
Success?:   Yes

Broken Blinds

Repair No. , 1900

Problem:    Trapped mechanism 
Solution:   Re-attach string and fasten 
Brand:  Ikea 
Cost new:   £80.00 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

Blinds came in that weren’t able to retract properly, the issue was that the string had come loose in the mechanism,and needed to be re-fed through the spindle and fixed in place.

Vacuum

Repair No. , 1900

Problem:    Belt had burnt through 
Solution:   Replace belt and clean head 
Brand:  Unkown 
Cost new:   ??? 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

The vacuum would create suction, but the head of the vacuum wouldn’t spin to pull up hair and dust. Having a look inside, the mechanism had gotten gunged up and was impossible to spin, and the belt to attach from the motor to the head had melted through. Thankfully the customers brought in a spare belt that came with the vacuum cleaner! Nice and easy fix to clean out the mechanism so that it could spin freely, and attach the new belt.

Portable Speaker Batteries

Repair No. , 1900

Problem:    Failed batteries
Solution:   New batteries
Brand:
Cost new:   £110
Cost of fix:£0
Age:
Success?:   Yes

Bosch Cute Drill

Repair No. , 1900

Problem:    Drill filled with sawdust, misaligning gearbox
Solution:   Clean out internals and reassemble
Brand:
Cost new:   £170
Cost of fix:0
Age:
Success?:   Yes

Headphones cable issue

Repair No. , 1900

Problem:    Intermittent connection 
Solution:   New audio cable 
Brand:  Generic 
Cost new:   £80.00 
Cost of fix:    0p 
Age:    TODO 
Success?:   Yes

Headphones came in that had an intermittent connection and would crackle on one of the speakers. Electrical test between them showed a bad connection in the 3.5mm jack end, and they’d already brought in a 3.5mm jack to replace it with. The quality of the existing cables wasn’t great so I thought it better and easier to swap it out for a moulded 3.5mm jack. Went through the junk collection we have and found a perfectly suitable one to replace it with, that saved the wire getting junked for scrap.

Bose Cinemate

Repair No. , 1900

Problem:    IR Receiver failed
Solution:   Replace IR Receiver
Brand:
Cost new:   £400
Cost of fix:60
Age:
Success?:   Yes

Headphone plastic fix

Repair No. , 1900

Problem:    Snapped plastic
Solution:   Insert copper rod
Brand:
Cost new:   £90
Cost of fix:0
Age:
Success?:   Yes

Multi-cooker resettable fuse

Repair No. , 1900

Problem:    Fuse blown - RESETTABLE
Solution:   Push button
Brand:
Cost new:   £220
Cost of fix:0
Age:
Success?:   Yes

Amplifier failed IC

Repair No. , 1900

Problem:    Main power IC failed
Solution:   Replace main amplifier IC
Brand:
Cost new:   £80
Cost of fix:£4
Age:
Success?:   Yes

Desk lamp disconnection

Repair No. , 1900

Problem:    Wires snapped off from lamp
Solution:   Re-solder wires to lamp
Brand:
Cost new:   £20
Cost of fix:0
Age:
Success?:   Yes

Audio Mixer USB Connector

Repair No. , 1900

Problem:    Broken USB Connector
Solution:   New USB connector
Brand:
Cost new:   £120
Cost of fix:£0.8
Age:
Success?:   Yes

Hidden thermal fuses

Repair No. , 1900

Problem:    Thermal fuse failure
Solution:   Replace thermal fuse
Brand:
Cost new:   £120
Cost of fix:50
Age:
Success?:   Yes

talks

Collective Anomaly Perception During Multi-Robot Patrol: Constrained Interactions Can Promote Accurate Consensus

This was my presentation to present the paper that I had accepted in the ACM Symposium on Applied Computing, which is a large conference with around 1000 attendees. The paper was on the topic of multi-robot patrol and how to detect anomalies in the environment that the robots are patrolling. The paper was accepted in the Robotics (IRMAS) track of the conference, and I presented it in a session with other robotics papers. The paper is available here