500SL Repairs

Our 1985 Mercedes 500SL has been undergoing some pretty extensive electrical work to address various issues and improve functionality:

• Dash Light Dimmer (Rheostat):
  The dimmer had failed, causing the dash lights to remain overly bright and reflect off the screen glass. Upon inspection, the rheostat was found to have no resistance across its rotation and was in poor condition. As this rare part is a sealed factory unit, replacement was not a viable option. Instead, the unit was carefully drilled open, disassembled, cleaned thoroughly, and reassembled. A broken wire connection was resoldered, and the original rivets were replaced with screws, converting it into a serviceable part. The rheostat now functions perfectly, dimming and switching off the dash lights as intended.
• Stereo and Speaker Installation:
  A new DAB stereo, speakers, and antenna were provided by the customer for installation. The old stereo and speakers were removed, but the new 180W speakers, with their larger magnets, required modifications to fit. Steelwork behind the mounts was adjusted, and the fascia fixing positions were modified to create sufficient clearance. New screw holes were drilled, and the fascia springs and brackets were adapted to ensure a factory-like fit. Although an antenna adapter is pending, the system was tested via Bluetooth, delivering excellent audio quality.
• Battery Clamp Replacement:
  The under-bonnet battery was previously secured with a makeshift softwood clamp. This was replaced with a custom-fabricated clamp made from 2mm sheet steel, which was drilled, shaped, and painted for durability. The new clamp provides a secure and professional solution.
• Heated Screen Issue:
  The heated screen for the hardtop was reported as non-functional. Testing revealed the switched 12V feed to be operational, but further investigation is not possible without the hardtop present.