Complete manual with clear schematic diagrams and printed circuit board layouts of two variants of the headset and the transmitter an old and a new version.
Also shows how the headset and the transmitter is opened and how transmitter and receivers can be adjusted and where to measure.
I had no problems to repair the headset using this service manual.
Text excerpt from page 7 (click to view)
Note: We recommend a 30 to 40 Watt soldering iron. An expert may be able to use a 60 to 80 Watt iron where someone with less experience could overheat and damage the PCB foil. - Flux Recommended Flux: Specific Gravity 0.82. Type RMA (lower residue, non-cleaning type)
Note: See ABOUT LEAD FREE SOLDER (PbF: Pb free) ().
7.2. PROCEDURE 1. Tack the flat pack IC to the PCB by temporarily soldering two diagonally opposite pins in the correct positions on the PCB.
Be certain each pin is located over the correct pad on the PCB.
2. Apply flux to all of the pins on the IC.
3. Being careful to not unsolder the tack points, slide the soldering iron along the tips of the pins while feeding enough solder to the tip so that it flows under the pins as they are heated.