GRUNDIG Service
2 - 2
M 100-CF
Einstellvorschriften / Adjustment Procedures
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. Adjustment of the tape transport see page 1 - 9.
2 - 4
1. Tape speed
2. Take-up torque
on Start
3. Wow and flutter
4. Head gap angle
(Azimuth)
5. Playback level
Reference tape
scanning
(Dolby level)
6. Erase frequency
7. Erase current
8. HX-PRO
9. Record blocking
circuits
(bias filter)
10. MPX-filter
(19kHz stereo
pilot tone)
With adjustment control R482 (Logic board) set the
frequency to 3150Hz
±
1.0%.
On START, the torque should be 30 to 60 x 10
-4
Nm
≈
40g-cm.
Deviation
≤
0.1% (IEC wtd).
Playback measuring time
≥
30 seconds.
Tape direction: "Normal"
With the head adjustment screw
E
set the left or right
channel to maximum level.
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 direction: "Reverse"
Adjustment with head adjustment screw
F
is the same as
in the "Normal" tape direction.
Set the playback level with the adjustment controls R135
(left) or R136 (right) to 490mV
±
0.5dB.
(LINE OUT
≈
950mV).
When using a test cassette with 200nWb/m set the play-
back level to 388mV
±
0.5dB.
(LINE OUT
≈
750mV).
The oscillator frequency should be 85kHz
±
10kHz.
Adjust with L111.
Erase current: 175mA
±
20% measured at R263
= 175mV
±
20%.
Adjust for minimum DC voltage with L113 at pin13 IC111
(left channel) and with L114 at pin6 IC111 (right channel).
Adjust for minimum RF with F111 at test point TP3 (left
channel) and F112 at test point TP4 (right channel).
Set the level control (RECORD LEVEL) during Record 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) or F102 (right channel).
Adjustment
Preparations
Adjustment Procedure
Frequency counter to LINE OUT.
Insert test cassette 448 A.
Play back 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 AF-voltmeter to LINE OUT L (left channel) or to
LINE OUT R (right channel).
Load test cassette 448 A, play back 10kHz.
AF-voltmeter to test point D1 (left channel) or D2
(right channel).
Insert test cassette 448 A.
Play back 315Hz (250nWb/m).
Dolby off.
Frequency counter to test point L1 (R263).
Insert a recordable cassette with ME tape (IEC IV).
Function: Record-Start.
AF-voltmeter to test point L1 (in parallel with R263).
Insert a recordable cassette with ME tape (IEC IV).
Function: Record-Start.
Connect the DC-voltmeter to Pin13 IC111 (left channel) or
to Pin6 IC111 (right channel).
Insert a recordable cassette with ME tape (IEC IV).
Function: Record-Start, Dolby off.
Connect the 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 ME tape (IEC IV).
Function: Record-Start, Level pot. minimum.
Connect the AF-generator (f
1
= 315Hz, f
2
= 19kHz, 500mV)
to the LINE IN sockets.
Connect the AF-voltmeter to the
test points
D1 (left channel)
or
D2 (right channel).
Insert a recordable cassette with ME tape (IEC IV).
Function: Record-Start, Dolby off.
Dolby off.
F
E
Tape run
"Reverse"
Tape run
"Normal"
≈
10 k
10 k
LINE IN
