Grundig CF 11 Serviceanleitung Seite 14

Einstellvorschriften / Adjustment Procedures CF 11
Adjustments
Measuring instruments/equipment:
Frequency counter, AF voltmeter, DC voltmeter, AF generator, distortion analyzer, wow and flutter meter,
Cr test cassette 448 A, torque test cassette 456.
1. Tape speed Frequency counter to LINE OUT. With adjustment control R482 (Logic board) set the
Insert test cassette 448 A. frequency to 3150 Hz+0.1%.
Play back 3150 Hz.
On START, the torque should be 30 to 60 x 10 Nm
= 40 g-cm.
2. Take-up torque
on Start
Load the torque test cassette 456.
Function: Start.
Wow and flutter meter to LINE OUT.
Load test cassette 448 A.
Play back 3150 Hz.
Deviation < 0.1% (IEC wid).
Playback measuring time > 30 seconds.
3. Wow and flutter
Connect AF-voltmeter to LINE OUT L (left channel) or to
LINE OUT R (right channel).
Load test cassette 448 A, play back 10 kHz.
Tape direction: "Normal"
With the head adjustment screw [E] set the left or right
channel to maximum level.
4. Head gap angle
(Azimuth)
Then connect the left channel in parallel with the right
channel (LINE OUT). By minimum re-adjustment of the
head adjustment screw/E]set the output level to maximum.
Turn around the test cassette.
Tape run Tape run
"Normal" "Reverse"
——_—_—_—> +—_—
Tape direction: "Reverse"
Adjustment with head adjustment screw [F] is the same as
in the "Normal" tape direction.
= F [=
Set the playback level with the adjustment controls R135
(/eft) or R136 (right) to 490 mV +0.5 dB.
(LINE OUT = 950 mV).
When using a test cassette with 200 nWb/m set the
playback level to 388 mV +0.5 dB.
(LINE OUT = 750 mV).
AF-voltmeter to test point O D1 (left channel) or O D2
(right channel).
Insert test cassette 448 A.
Play back 315 Hz (250 nWb/m).
Dolby off.
5. Playback level
Reference tape
scanning
(Dolby level)
The oscillator frequency should be 85 kHz + 10 kHz.
Adjust with L111.
6. Erase frequency | Frequency counter to test point O L1 (R263).
Insert a recordable cassette, Cr tape (IEC Il).
Function: Record-Start.
Erase current: 150 mA + 10% measured at R263
= 150 mV + 10%.
7. Erase current AF-voltmeter to test point © L1 (in parallel with R263).
Insert a recordable cassette with Cr tape (IEC II).
Function: Record-Start.
Adjust for minimum DC voltage with L113 at pin13 1C111
(left channel) and with L114 at pin6 1C111 (right channel).
8. HX-PRO Connect the DC-voltmeter to Pin13 1C111 (left channel)
or to Pin6 1C105 (right channel).
Insert a recordable cassette with Cr tape (IEC Il).
Function: Record-Start, Dolby off.
Adjust for minimum RF with F111 at test point O TP3 (left
channel) and F112 at test point O TP4 (right channel).
Connectthe AF-voltmeter to test point © TP3 (left channel)
or to test point © TP4 (right channel) on the audio circuit
board.
Insert a recordable cassette with Cr tape (IEC Il).
Function: Record-Start, Level pot. closed.
9. Record blocking
circuits
(bias filter)
10. MPX-filter
(19 kHz stereo
pilot tone)
Connect the AF-generator (f; = 315 Hz, fo = 19 kHz, ca. | Set the level control (RECORD LEVEL) during Record so
115 mV) to the LINE IN sockets. that at 315 Hz the voltage measured at the test points
© D1 and © D2 is V, = 388 mV (= 0 GB).
At 19 kHz = V, <12 mV (<—30 dB). Connect the AF-voltmeter to the
test points © D1 (left channel)
or © D2 (right channel).
Function: Record-Start,
balance control to "mid-position",
Dolby off.
Adjust with F101 (left channel) or F 102 (right channel).
2-4 GRUNDIG Service