Einstellvorschriften / Adjustment Procedures
CF 21
2 - 4
GRUNDIG Service
With adjustment control R535 (Logic board) set the
frequency to 3150Hz
±
0.1%.
On START, the torque should be 25 to 70 x 10
-4
Nm
≈
40g-cm.
Deviation < 0.13% (IEC wtd.).
Playback measuring time
≥
30 seconds.
Set the level control (RECORD LEVEL) during Record-
Pause so that at 315Hz the voltage measured at the test
points
D1 and
D2 is V
o
= 388mV (= 0dB).
At 19kHz = V
o
≤
12mV (
≤
–30dB).
Adjust with F101 (left channel) and F102 (right channel)
respectively.
The oscillator frequency should be 85kHz
±
10kHz.
Adjust with L103.
Erase current: 100mA
±
10%
measured at R253 = 100mV
±
10%.
Adjust for minimum DC voltage with L104 at pin13 IC105
(right channel) and with L105 at pin6 IC105 (left channel).
Adjust for minimum RF with F106 at test point
D3 (left
channel) and F105 at test point
D4 (right channel).
Set the playback level with the adjustment control R156
(left channel) and R157 (right channel) respectively to
490mV
±
0.5dB (LINE OUT
≈
950mV).
When using a test cassette with 200nWb/m set the playback
level to 388mV
±
0.5dB (LINE OUT
≈
750mV).
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
Preparations
Adjustment Procedure
Frequency counter to LINE OUT.
Insert the test cassette 448 A,
play 3150Hz.
Load the torque test cassette 456.
Function: Start
Wow and flutter meter to LINE OUT.
Load test cassette 448 A.
Play back 3150Hz.
Connect the AF-generator (f
1
= 315Hz, f
2
= 19kHz, ca.
115 mV) to the LINE IN sockets.
Connect the AF-voltmeter to the
test points
D1 (left channel)
and
D2 (right channel) respectively.
Function: Record-Pause, Dolby off,
balance control to "mid-position"
Connect the frequency counter to
L1 (R253).
Insert a recordable cassette, Cr tape (IEC II).
Function: Record-Start
Connect the AF-voltmeter to
L1 (in parallel with R253)
Insert a recordable cassette with Cr tape (IEC II).
Function: Record-Start
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
Connect the AF-voltmeter to test point
D3 (left channel)
and to test point
D4 (right channel) respectively.
Insert a recordable cassette with Cr tape (IEC II).
Function: Record-Start, Level pot. minimum
Connect the AF-voltmeter to test point
D1 (left channel)
and test point
D2 (right channel) respectively.
Load the test cassette 448 A.
Playback 315Hz (250nWb/m).
Dolby off
Connect AF-voltmeter to LINE OUT L (left channel) and to
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).
k
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
refers to a point in the circuit diagram.
1. Tape speed
2. Take-up torque
on Start
3. Wow and flutter
4. MPX-filter
(19kHz stereo pilot
tone)
5. Erase frequency
6. Erase current
7. HX-PRO
8. Record blocking
circuits
(bias filter)
9. Playback level
Reference tape
scanning
(Dolby level)
10.Head gap angle
(Azimuth)
≈
10 k
10 k
LINE IN
1
ro Cho
HIFI SINGLE CASSETTE DECK
CF21
2
2
