Probably it never existed a 1081 official service manual from Commodore, it's look more like a NAPCEC service manual & diagrams compilation of the 1084 series and his variants, like the nap6523, 8cm505, 1084S, 1084P and obviously the 1081. It's more complete than other scans and the quality of the scans also are far superior. It has two circuit diagrams variants of the 1081, mono and stereo versions. It doesn't include a diagram for the Philips CM8500 or CM8501, they look like the 1081 but they are slightly different.
Text excerpt from page 16 (click to view)
Pin No. 73 74 75 76 77
Pin Name VDD5V VSS CONT6 CONT7 V/*P
I/O � � I/O I/O O
Description Microprocessor interface power supply. (2000pF or more path controller to be inserted at a point nearer to the pin between this pin and GND) Digital ground pin. Must be connected to 0V. General-purpose input/output pin 6. General-pirpose input/output pin 7. Rough servo/phase control automatic switching monitor output pin. �H� for rough servo and �L� for phase servo. Synchronization signal detection output pin. Outputs a high level when the
78
FSEQ
O
synchronization signal detected from the EFM signal and the internally generated synchronization signal agree.
79 80
DEFECT EFMO
I/O O
Defect pin. Which becomes an input pin after reset and can be controlled externally. This becomes the defect monitor pin under control by command. EFM signal output pin.