Grundig TVR 3735 FR/TOP Servicehandbuch Seite 64

Drive Mechanism
4.3 Height and Azimuth of the A/C Head
– Connect the oscilloscope to connector PY01-(1).
– Play the test cassette with the 6kHz Standard Sound audio signal
recording.
– Set the height adjustment screw (Pos. A1400, Fig. 24) for maximum
output voltage.
– Set the azimuth adjustment screw
voltage.
4.4 X-Value
– Connect the 10:1 test probes of the dual-channel oscilloscope
(triggering channel A) as follows:
• Channel A: head switching pulse "SW" – connector contact PY04-(6)
• Channel B: FM envelope "PB ENV"– connector contact PY04-(4)
– Play the test cassette
– Activating the Service Mode:
• Press button h and confirm with the G button.
• With the buttons CD select "SPECIAL FUNCTIONS" and confirm
with the G button.
• With the buttons CD select "SERVICE" and confirm with the G
button.
• With the buttons CD select "SERVICE CODE" and enter the code
number 8 5 0 0.
• With the buttons CD select "ATK off".
– The following tracking functions can be selected successively by
pressing the G button: "ATK off – off", "ATK off – center",
"ATK off – max", "ATK off – min".
With the X-value adjustment screw
position adjust the X-value in mechanical mid-position in the tracking
functions "ATK off – max" and "ATK off – min" to obtain FM packages
of the same amplitude.
– Check the reverse rollers of the threading roller units (point 4.1).
– Check the height and azimuth of the A/C head (point 4.3).
– Terminating the Service Mode:
• With the buttons CD select "END".
• With the buttons F E select "with mem.", confirm with the G
button and finally press button "TXT".
4.5 Adjusting the Tape Path
4.5.1 Coarse adjustment
– Connect the 10:1 test probes of the dual-channel oscilloscope
(triggering channel A) as follows:
• Channel A: head switching pulse "SW" – connector contact
PY04-(6)
• Channel B: FM envelope "PB ENV"– connector contact PY04-(4)
– Play the test cassette.
– Adjust the reverse rollers /
1 2
at the tape lead-in and lead-out side do not exceed the limit value
b / a ≤ 0.75 (Fig. 25).
5 - 10
(Fig. 24) for maximum output
5
(Fig. 24) in mechanical mid-
6
(Fig. 22) so that the FM packages
a
Fig. 25
4.5.2 Fine adjustment
– Set the X-value (point 4.4).
– Connect the 10:1 test probes of the dual-channel oscilloscope
(triggering channel A) as follows:
• Channel A: head switching pulse "SW" – connector contact PY04-(6)
• Channel B: FM envelope "PB ENV"– connector contact PY04-(4)
– Play the test cassette.
– Set the tracking position manually so that noise just starts to appear
in the picture.
– Set the reverse rollers /
1 2
FM packages is as flat as possible.
– Tape riding over the upper edge:
turn the left reverse roller
wise
turn the right reverse roller
wise
– Tape riding over the lower edge:
turn the left reverse roller
terclockwise
turn the right reverse roller
terclockwise
4.5.3 Check
– Connect the 10:1 test probes of the dual-channel oscilloscope
(triggering channel A) as follows:
• Channel A: head switching pulse "SW" – connector contact PY04-(6)
• Channel B: FM envelope "PB ENV"– connector contact PY04-(4)
– Play the test cassette
– Press the "picture search reverse" button followed by the "play"
button after 15 seconds. After another 3 seconds the FM packages
must recover their maximum amplitude and flat envelope. If neces-
sary, re-adjust the reverse rollers
– Check the tilt of the A/C head (point 4.2).
– Check the height and azimuth of the A/C head (point 4.3).
– Check the X-value (point 4.4).
– Check the setting of the head position indicator (see Adjustment,
page 2-4)
TVR 3735..., TVR 3740..., TVR 5540...
b
b/a ≤ 0.75
(Fig. 22) so that the amplitude of the
(Fig. 22) clock-
1
(Fig. 22) clock-
2
(Fig. 22) coun-
1
(Fig. 22) coun-
2
/ (Fig. 22).
1 2
GRUNDIG Service