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 8 (click to view)
KRC-765/691/691Y
ADJUSTMENT
BALANCE/FADER/BASS/MID/TREBLE : CENTER T.ADV/METAL/DOLBY NR : OFF No. ITEM INPUT SETTINGS TCC-153 10kHz OUTPUT SETTINGS SP OUT Connect an AC voltmeter to CN5 (X14-). ALIGNMENT POINTS Head azimuth screw (FWD/REV) VR1 (L) VR2 (R) ALIGN FOR Adjust so that output level in playing FWD and REV becomes maximum each. 388mV FIG.