Table des Matières
Publicité
Adjustment Procedures
1.4 Chassis Board – Frontend (FV)
Test equipment: Oscilloscope with 10:1 Test Probe, Voltmeter, AF Millivoltmeter, Colour Generator
Service work after replacing the
... Tuner, IC7720, IC7721: Adjustments no. 2
... IC7720 (TDA9800T): Remove R3748
... IC7780: Adjustments no. 4, 5
Adjustment
1. Demodulator Circuit
Voltmeter: ................................. IC7720-(15) or IC7721-(20)
EE-mode.
PAL, F5725
Colour generator 38.9MHz - 500mV
(AFC)
SECAM-L,
Colour generator 33.9MHz / 500mV
R3748
Press button "SYSTEM" repeatedly until "SEC" is displayed.
(Band I)
2. Delayed AGC
Feed in a PAL white test pattern with sound carrier (without sound
Voltage,
modulation, Ch27, 74dBµV aerial signal) into the warmed-up VCR.
R3742
Oscilloscope: .............................................. Tuner 1701-(17)
(AGC)
EE-mode.
3. Residual Carrier
Colour generator 40.4MHz - 300mV
Band I,
Oscilloscope: ........................................................ F1720-(1)
F5721
EE-mode.
(40.4MHz)
4. Stereo Level
Call up the Service Test Programme (see page 2-4).
Call up Level 60 (see page 2-4).
5. Cross Talk
Call up the Service Test Programme (see page 2-4).
Call up Level 61 (see page 2-4).
1.5 Chassis Board – Video/Chroma (VS, VS-S)
Test equipment: Oscilloscope with 10:1 Test Probe, Colour Generator
Service work after replacing the IC7007 or 7110: Adjustment no. 1
Adjustment
1. Chroma Recording
Remove the drive mechanism (see page 1-9)
Current
Call up the Service Test Programme – Level 10 (see page 2-4)
Feed in a PAL red raster test pattern with 75% saturation (ratio
burst: chroma = 1 : 2.2) into the AV1 socket and record it.
Oscilloscope: ................................ R3031 (T7006 – Emitter)
Connect R3031 (T7006 – Emitter) to L5001 (5VASW).
PAL,
Oscilloscope: ................................................ R3007 – wiper
R3007
Feed in a PAL red raster test pattern with 75% saturation (ratio
(PAL-Curr.)
burst: chroma = 1 : 2.2) into the AV1 socket and record it.
SECAM-L,
Oscilloscope: ................................................ R3159 – wiper
R3159
Feed in a SECAM-L red raster test pattern with 75% saturation
(SECAM-Curr.)
(ratio burst: chroma = 1 : 2.2) into the AV1 socket and record
it.
1.6 Chassis Board – Standard Sound (AL)
Test equipment / aids: Frequency Counter, AF Millivoltmeter, AF Generator, Colour Generator, branded Video Cassette.
Service work after replacing the RP-Head, L5603 or IC7007: Adjustment no. 1, 2
Adjustment
1. Erase Frequency,
Frequency counter: ....................... wire bridge 9034 (Head)
F5603
Record
(BIAS R)
1.1 Bias, R3618
AF millivoltmeter: .......................... BIAS1 or BIAS2 (R3606)
(BIAS)
Record.
1.2 Frequency
– Feed in a CCVS signal via EURO-AV1 socket, contact 20.
Response Test
– Feed an audio signal of 200mV
generator to the EURO-AV1 socket, contact 2 or 6.
– Make a recording of 400Hz and 8kHz each of 1 min at least.
Afterwards play back these recordings (MONO).
– Connect an AF millivoltmeter (oscilloscope) to EURO-AV1
socket, contact 1 or 3.
2. Playback Level for
AF millivoltmeter: ............ EURO-AV1 socket, contact 1 or 3
Mono VCR,
AF generator (1kHz / 0.7V
R3160
........................................ EURO-AV1 socket, contact 2 or 6
(PB-Lev.)
Feed in a CCVS signal via EURO-AV1 socket, contact 20.
Play back the self made recording (Normal Play).
for Stereo VCR
Call up the Service Test Programme (see page 2-4).
Call up Level 62 (see page 2-4).
3 - 4
. The new TDA9800T automatically sets a "Default" value.
(PLL)
Preparation
: ...... Tuner 1701-(17)
PP
: ...... Tuner 1701-(17)
PP
: ...... Tuner 1701-(17)
PP
Preparation
Preparation
(480mV
) from the AF
rms
PP
):
rms
Adjustment Procedure
Set the voltage with F5725
(AFC)
Set the voltage with R3748
(Band I)
Set the amplitude with R3742
(AGC)
Set the amplitude with F5721
(40.4MHz)
lower at least than the input signal).
Observe the instructions for Level 60 (see page 2-6).
Terminate the Service Test Programme (see page 2-4).
Observe the instructions for Level 61 (see page 2-6).
Terminate the Service Test Programme (see page 2-4).
Adjustment Procedure
The FMF signal must have an amplitude of 420mV
value deviates by more than ±40mV
defect (e.g. IC7007).
Set Chroma signal with R3007
(PAL-Curr.)
±
(for 2-Head-VCR) or 130mV
20mV
PP
Set Chroma signal with R3159
(SECAM-Curr.)
Terminate the Service Test Programme, disconnect R3031
from L5001 and reassemble the drive mechanism.
Adjustment Procedure
With F5603
set the frequency to 70kHz
(BIAS R)
Set the voltage drop across R3600 with R3618
15mV
.
rms
Check the frequency response.
The voltage ratio of 400Hz to 8kHz must not be higher than
1:0.7 or 0.7:1 (±3dB). If the voltage ratio exceeds these limits,
the bias must be altered:
To increase the playback voltage at 8kHz: Reduce "BIAS".
To reduce the playback voltage at 8kHz: Increase "BIAS".
Set output voltage with R3160
(PB-Lev.)
Observe the instructions for Level 62 (see page 2-6).
Terminate the Service Test Programme (see page 2-4).
GV 27 EURO, GV 7... EURO
±
to 2.5V
0.2V.
±
to 2.5V
0.2V.
to 550mV
+0/-50mV.
PP
to minimum (5dB
. If the
pp
there is a technical
pp
±
to 160mV
20mV
PP
PP
(for 4-Head-VCR).
PP
±
to 210mV
30mV
.
PP
PP
±
10kHz.
to
(BIAS)
±
to 0.5V
50mV.
rms
GRUNDIG Service
Publicité
Table des Matières
