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Einstellvorschriften / Adjustment Procedures
Adjustment Procedures
Measuring instruments/equipment:
Frequency counter, AF-voltmeter, DC-voltmeter, AF-generator, distortion analyzer, wow and flutter meter,
Cr test cassette 448 A (part no. 35079-023.00), torque test cassette 456 (part no. 35079-014.00).
Layout of adjustment controls see page 2 - 3. The symbol
Adjustment
1. Tape speed
Frequency counter to LINE OUT.
Insert the test cassette 448 A,
play 3150Hz.
2. Take-up torque
Load the torque test cassette 456.
on Start
Function: Start
3. Wow and flutter
Wow and flutter meter to LINE OUT.
Load test cassette 448 A.
Play back 3150Hz.
4. MPX-filter
Connect the AF-generator (f
(19kHz stereo pilot
115 mV) to the LINE IN sockets.
tone)
Connect the AF-voltmeter to the
test points
and
Function: Record-Pause, Dolby off,
balance control to "mid-position"
5. Erase frequency
Connect the frequency counter to
Insert a recordable cassette, Cr tape (IEC II).
Function: Record-Start
6. Erase current
Connect the AF-voltmeter to
Insert a recordable cassette with Cr tape (IEC II).
Function: Record-Start
7. HX-PRO
Connect the DC-voltmeter to Pin13 IC105 (right channel)
and to Pin6 IC105 (left channel) respectively.
Insert a recordable cassette with Cr tape (IEC II).
Function: Record-Start, Dolby off
8. Record blocking
Connect the AF-voltmeter to test point
circuits
and to test point
(bias filter)
Insert a recordable cassette with Cr tape (IEC II).
Function: Record-Start, Level pot. minimum
9. Playback level
Connect the AF-voltmeter to test point
Reference tape
and test point
scanning
Load the test cassette 448 A.
(Dolby level)
Playback 315Hz (250nWb/m).
Dolby off
10.Head gap angle
Connect AF-voltmeter to LINE OUT L (left channel) and to
(Azimuth)
LINE OUT R (right channel) respectively.
Load the test cassette 448 A.
Playback 10kHz.
The head adjustment screw 1 is accessible by removing
the cassette compartment lid cover (with open cassette
compartment disengage 2 the cover at the bottom and
push it upwards to remove it).
2 - 4
refers to a point in the circuit diagram.
Preparations
= 315Hz, f
1
D1 (left channel)
D2 (right channel) respectively.
L1 (in parallel with R253)
D4 (right channel) respectively.
D2 (right channel) respectively.
HIFI SINGLE CASSETTE DECK CF21
ro Cho
2
2
With adjustment control R535 (Logic board) set the
frequency to 3150Hz
On START, the torque should be 25 to 70 x 10
≈ 40g-cm.
Deviation < 0.13% (IEC wtd.).
Playback measuring time ≥ 30 seconds.
= 19kHz, ca.
Set the level control (RECORD LEVEL) during Record-
2
Pause so that at 315Hz the voltage measured at the test
10 k
points
D1 and
≈
10 k
LINE IN
At 19kHz = V
Adjust with F101 (left channel) and F102 (right channel)
respectively.
L1 (R253).
The oscillator frequency should be 85kHz
Adjust with L103.
Erase current: 100mA
measured at R253 = 100mV
Adjust for minimum DC voltage with L104 at pin13 IC105
(right channel) and with L105 at pin6 IC105 (left channel).
D3 (left channel)
Adjust for minimum RF with F106 at test point
channel) and F105 at test point
D1 (left channel)
Set the playback level with the adjustment control R156
(left channel) and R157 (right channel) respectively to
±
0.5dB (LINE OUT ≈ 950mV).
490mV
When using a test cassette with 200nWb/m set the playback
level to 388mV
With the head adjustment screw 1 set the left or right
channel to maximum level.
Then connect the left channel in parallel with the right
channel. By minimum re-adjustment of the head adjustment
screw 1 set the output level to maximum.
Adjustment Procedure
±
0.1%.
D2 is V
= 388mV (= 0dB).
o
≤
12mV (≤ –30dB).
o
±
10kHz.
±
10%
±
10%.
D4 (right channel).
±
0.5dB (LINE OUT ≈ 750mV).
1
GRUNDIG Service
CF 21
-4
Nm
D3 (left
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