Koss KSC75 Driver Replacement

Introduction

If your Koss KSC75 headphones are producing no sound, distorted audio, or intermittent sound, this guide will help you replace the driver. This guide will walk you through the process of accessing, cutting, and resoldering the headphone wires to restore proper audio function.

This repair involves soldering, which is the process of joining metal components using melted solder. If you have never soldered before, check out this How to Solder and Desolder Connections guide for a basic understanding. Additionally, since you’ll need to strip wires, you may find this Wire Stripping Guide useful before starting.

Before starting, confirm that the issue is not caused by a faulty audio source by testing your headphones with another device. If the problem persists across different devices, follow this guide to repair the wiring inside your headphones.

Important Warning: Soldering irons are extremely hot and can burn skin or damage components. Work in a ventilated area, handle wires carefully, and avoid crossed connections to prevent short circuits and permanent damage.

What you need

Step 1 Koss KSC75 Driver Replacement

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Remove the ear clip by gently pulling it away from the headphone.
Peel off the ear cushion by gripping the edges and slowly pulling it away from the earpiece.

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Step 2

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Locate the wire plate at the bottom of the earphone where the wire enters the earpiece.
Grip the earphone firmly by the sides and use your fingers to gently pry off the plate.
Potential for driver damage; do not use excessive force when removing the plate. Hold the earphone by the sides.

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Step 3

Use a wire cutter to carefully cut the wire close to where it is soldered on the board to detach the wire from the driver.
If you are unsure which wire is soldered to the board: Follow the wire from the headphone cable entry point to where it connects inside the earpiece. Look for two or more thin wires attached to small metal dots (solder joints) inside the casing.

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Step 4

If the wire is frayed, broken, or discolored, use wire cutters to cut at least ½ inch (1–2 cm) beyond the visibly damaged area. Cut straight across the wire to ensure even ends.
Cutting too short can make it harder to reconnect the wire to the circuit board. Leave enough slack for soldering.
If you are using a razor, put the wire on a flat surface and carefully slice with little pressure to avoid pressing the blade into your finger.

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Step 5

Insert the wire into the hole of the wire stripper about ¼ inch (5 mm) from the end.
Gently squeeze the handles and rotate the stripper around the wire once.
Pull off the cut insulation while keeping the wire steady.
You should end up with about ¼ inch (5 mm) of exposed copper strands.
Separate the two tiny wires inside the headphone cable.

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Step 6

Plug in and preheat your soldering iron according to the solder you're using:
Leaded solder: 315–350°C (600–660°F)
Lead-free solder: 370–400°C (700–750°F)
The soldering iron tip is extremely hot. Avoid touching it directly and keep flammable materials away. Always solder in a well-ventilated area or with a fume extractor running.
Dip the exposed wire ends into flux to help the solder bond better.
Apply a small amount of soldering wire onto the tip of the iron to "tin" it, which helps with heat transfer.
If you notice smoke coming from the flux, this is normal and helps clean the metal surface.

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Step 7

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Do not overheat the terminals, as too much heat can damage the driver.
Identify the soldering terminals inside the earpiece, then secure the wire in place by positioning the exposed end over the correct terminal. There are usually two per side:
One for the signal wire (red or green).
One for the ground wire (bare copper or gold)
With one hand, hold the soldering iron against the wire and terminal for 1–2 seconds to heat the connection.
With your other hand, feed solder to the joint so it melts and flows around the wire.
Remove the soldering iron and let the solder cool for a few seconds before moving the wire.
Repeat for the second wire, ensuring both connections are secure and not touching each other before proceeding.

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Step 8

Inspect all soldered connections to make sure the wires are firmly attached and not touching other components.
Gently tug the wire to test its strength. If it comes loose, re-solder it.
A good solder joint should be smooth and secure. If rough or cracked, reheat and add solder. Lead-free solder may appear dull instead of shiny—this is normal. Focus on a strong connection.