How to Repair Marshall Major I Headphone

Over time, under lights exposure and subject to diverse environmental factors, paint, coating and plastics degrade. This happened for my now almost 7+ years old Marshall Major I headphone.

Even though the electronics seems to be as good as the first day the audio cord and the ear pads cushions are tearing apart and the coating on the plastics is becoming sticky. Instead of buying a brand new one, I decided to take it apart and see how repairable it would be. A 3.5 mm female stereo jack will be added to allow the easy removal of the audio cable.

Tools:

• PH1 screw driver
• PH00 screw driver
• cutter blade
• all purposes glue
• soldering iron
• solder wire
• some gasoline to remove the coil

Spare parts:

• 3.5 mm double-ended stereo coil cord with mic and remote control (~13€); here we will have the headphone side as TRS (Tip-Ring-Sleeve, supporting stereo sound but no microphone) and the other end (e.g. smartphone) as TRRS (Tip-Ring-Ring-Sleeve, supporting stereo and microphone).
• 3.5 mm female stereo headphone socket TRS, with soldering pads visible or with accessible wires (~1€); got mine from an old USB stick music player. It has to be as small as possible so as to fit in the earpiece.
• 61cm double strand braided cable (e.g. 2x 0.14mm² for audio) - chose the color wisely as it will partially be visible
• 2x new ear pads cushions (~13€)

The following steps are identical for both headphone sides:

1. Remove the first screw you see when you follow the cable coming from the earpiece to the headband.
2. Fold back the headset to reveal two screws, unscrew them.
3. Disassemble both plastic parts that are now loose, releasing the metal guide.
4. Remove the ear pad by softly pinching and pulling on corner of the cushion.
5. Remove the four screws to free the loudspeaker.
6. Unsolder all wires.
7. Take apart the seal and cover with the Marshall brand.

Make sure to put the screws in a small box to find them back when you will assemble the whole headphone again.

That is the trickiest part of the disassembly.

For both headphone sides:

1. Use the thin cutter blade to dislocate the goldy and shiny Marshall metal plate.
2. Loosen the no fewer than five screws that are now visible.
3. Disassemble both parts to release the cable.

The headband now has the cable that brings the audio from one hear to the other one, hardened by a metal bow. The metal bow can be removed, then to remove the audio cable:

1. Cut a 61cm chunk from the double stranded cable.
2. Make a knot with the new cable and the old one, then pull through.

The coil on the plastic that became sticky, can be removed with some gasoline and by rubbing for some time.

The paint on the metalic guides also falling apart, I decided to completely remove it and let the metallic gray come out. Simply used the non sharp edge of the cutter blade to scratch off the paint.

The headband thin protective layer that come on your hairs has been removed completely and the tissue let free. The above leather could be changed or a new material can be put on top if necessary.

Adding the new 3.5mm connector means soldering three pins: left, right and common.

Original cable colors:

• Red: left
• Green: right
• Gold: common

Refer to the scheme and solder the 3.5mm socket accordingly. I did reuse the colored wires from the old cord for the wiring.

The connected can then be glued to the earpiece and/or attached to the inner plastic pins with some threads/wires. It has to withstand the cord (un)plugging constraints.

Re-assembling the headphone is simply a matter of gluing (Marshall metal plates) and screwing things back together.

• Earpads cushions replacement - https://www.youtube.com/watch?v=aFcfqf1igFs
• Adding a 3.5mm jack - https://www.youtube.com/watch?v=7GvsHBUk1uo
• Make your headphone wireless - https://www.youtube.com/watch?v=E_Ofzj1hnIs

• 3.5mm Audio Jack (Male) - https://components101.com/connectors/35mm-audio-jack