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 6 (click to view)
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3. SCHEMATIC DIAGRAM
A
3.1 CS Assy (Front, Surround)
Network Assy (SWN6020)
Red Red
INPUT
Black Black Blue
Woofer
B
Woofer
White
Red Short Leg Long Leg C 1.8µF/63V White
Tweeter
C
3.2 CS Assy (Center)
Connecting Cord (SDD1345)
Red