Panasonic PV-L452 Service Manual page 62

If the envelope is output poorly, much noise will appear in the
picture. Then the tracking will lose precision and the playback
picture will be distorted by any slight variation of the tracking
control circuit.
1. Put the unit into the service mode "I. Tracking Fix" to defeat Auto
Tracking. Refer to "SERVICE MODE SPECIFICATION (SELF-
DIAGNOSTIC SYSTEM)" in "SERVICE NOTES."
2. Connect the oscilloscope to Pin 32 (Envelope signal) on the TP
Adjustment P.C.B. Use Pin 33 (Head Switch signal) as a trigger.
3. Play back the VHS-C Alignment Tape (VFMS0004H6C).
4. Confirm that the RF envelope is flat enough. If not, with Flat
Headed (—) Screwdriver, adjust S and T post height so that the
envelope waveform becomes as flat as possible (No envelope
drop). If the envelope drop appears on the left-half of the
waveform, adjust S post height. If the envelope drop appears on
the right-half of the waveform, adjust T post height.
CAUTION: Do not apply excessive pressure onto the S and T Posts
when adjusting S and T post height.
Fig. M3-1
Fig. M3-2
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