The service manual is a good quality scan of the Panasonic NV-850, which is electrically identical to the Philips VR 6920, but mecanically just nearly.
The service manual is a good quality scan of the Blaupunkt RTV-404, which is electrically and mecanically identical to the Panasonic NV-830.
Text excerpt from page 52 (click to view)
Attachment A
Page 1 of 5
Procedure to fix the Screen VR on FBT of CM771
1.Preparation (1) Solder tool with flat head.(Refer to Photo 1 and 2) 2.Operation (1) Chassis adjustment should be completed. (2) Attach the head of solder tool softly on the right side of Screen VR knob together with FBT body for approximately 5 seconds to melt them. (Refer to Photo 3 and 4) (3) Attach the head of solder tool softly on the left side of Screen VR knob together with FBT body for approximately 5 seconds to melt them. (Refer to Photo 5 and 6) (4) Attach the head of solder tool on the top of Screen VR knob for approximately 7 seconds to melt it. (Refer to Photo 7 and 8) (5) Check Screen VR can not be turned and the G2 voltage is within 600+/-10V.