This is the most referenced part of the manual. The RD3 01 uses two main ISO blocks (A and B) plus an antenna diversity connector.
Typically provides more than 10W x 4 channels . siemens vdo rd3 01 service manual full
Usually caused by a dirty laser lens. You can often fix this with a laser cleaning disc or by carefully opening the top casing and using an isopropyl alcohol-dipped swab. This is the most referenced part of the manual