Grundig GV 26, Руководство по обслуживанию, Страница: 32 / 82

Adjustment Procedures GV 26 …, GV 46 …, GV 6000 …, GV 6001 V+, GV 6066, GV 6300 …
k
3 - 4
GRUNDIG Service
3.2 Family Board – Frontend (FV)
Test equipment: Oscilloscope with 10:1 Test Probe, Voltmeter, Colour Generator
Service work after replacing the
… Tuner: Adjustments no. 2
… IC7720 (TDA9800T): Remove R3740
(Phase Offset)
. The new TDA9800T automatically sets a "Default" value.
Adjustment Preparation Adjustment Procedure
1. Demodulator Circuit
PAL, F5725
(AFC)
SECAM-L,
R3748
(Band I)
2. Delayed AGC
Voltage,
R3742
(AGC)
Voltmeter: ................................. IC7720-(15) or IC7721-(20)
EE-mode.
Colour generator 38.9MHz / 100mV
PP
(IC7720)
or 200mV
PP
(IC7721): ................................. Tuner 1701-(17).
IC7721-(7) and T7726 – connect the collector to GND (activates
SECAM – Band I).
Colour generator 33.9MHz / 200mV
PP
: ......... Tuner 1701-(17).
Feed in a PAL white test pattern with sound carrier (without
sound modulation, UHF-range, Ch27, 67dB
µ
V aerial signal)
into the warmed-up VCR.
Oscilloscope: .............................................. Tuner 1701-(17)
EE-mode.
Set the voltage with F5725
(AFC)
to 2.5V
±
0.2V.
Set the voltage with R3748
(Band I)
to 2.5V
±
0.2V.
Disconnect IC7721-(7) and T7726 – collector from GND.
Set the amplitude with R3742
(AGC)
to 550mV
PP
+0/-50mV.
3.3 Family Board – Video/Chroma (VS)
Test equipment: Oscilloscope with 10:1 Test Probe, Frequency Counter, Colour Generator
Adjustment Preparation Adjustment Procedure
Set frequency with R3057
(Sync. Frequ.)
to 3.8MHz
±
10kHz.
Set Chroma signal with R3038
(PAL-Curr.)
to 71mV
PP
(-12.5dB
of the FM-signal).
Set Chroma signal with R3042
(SECAM-Curr.)
to 42mV
PP
(-17dB
of the FM-signal).
Disconnect IC7051-(2) from +5V.
AV recording (do not feed in a signal).
Frequency counter: ......................................... 9013 (FMRV)
Connect IC7051-(2) to +5V (pin 13).
Oscilloscope: .................................................. 9013 (FMRV)
Feed in a PAL red raster test pattern with 75% saturation (ratio
burst: chroma = 1 : 2.2) into the AV socket and record it.
Feed in a SECAM-L red raster test pattern with 75% saturation
(ratio burst: chroma = 1 : 2.2) into the AV socket and record
it.
1. Sync Frequency
R3057
(Sync. Frequ.)
2. Chroma Recording
Current
PAL (only with
R3038 fitted),
R3038
(PAL-Curr.)
SECAM-L,
R3042
(SECAM-Curr.)
3.4 Family 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: Adjustment no. 1.1, 2
Adjustment Preparation Adjustment Procedure
With F5603
(BIAS R)
set the reading on the frequency counter
to 70kHz
±
10kHz.
Set the voltage drop across R3600 with R3618
(BIAS)
to
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".
Remove the 270
Ω
resistor between IC7601-(10) and ground.
Set output voltage with R3606
(PB-Lev.)
to 0.5V
rms
±
50mV.
Frequency counter: ............................................. IC7601-(1)
Record
AF millivoltmeter: ........................................................ R3600
Record.
– Connect IC7601-(10) via 270
Ω
resistor to ground.
– Feed in a CCVS signal via EURO-AV socket, contact 20.
– Feed an audio signal of 200mV
rms
(480mV
PP
) from the AF
generator to the EURO-AV socket, contact 2 or 6.
– Make a recording of 400Hz and 8kHz each of 1 min at least.
Afterwards play back these recordings.
– Connect an AF millivoltmeter (oscilloscope) to EURO-AV
socket, contact 1 or 3.
AF generator (1kHz / 0.7V
rms
):
.......................................... EURO-AV socket, contact 2 or 6
AF millivoltmeter: .............. EURO-AV socket, contact 1 or 3
Record (Normal Play).
Play back this recording.
1. Erase Frequency,
F5603
(BIAS R)
1.1 Bias, R3618
(BIAS)
1.2 Frequency
Response Test
2. Playback Level,
R3606
(PB-Lev.)
3.5 Family Board – OSD (OS)
Test equipment / aids: Frequency counter, Colour Generator
Adjustment Preparation Adjustment Procedure
1. OSD, C2820
(only with C2820
fitted)
Connect IC7800-(23) to ground (pin 22).
Feed in a PAL white test pattern (UHF-range, Ch27, 67dB
µ
V
aerial signal). EE mode.
Frequency counter: ............................................ IC7800-(5)
Set the frequency with C2820 to 17,734.475kHz
±
100Hz.
Disconnect IC7800-(23) from ground.