Teletext "Dos" (Vt) - Grundig GV 640 NIC Betriebsanleitung

Adjustment Procedures
5. IO Board – Audio (AU)
5.1 IO Board – FM Sound
Test equipment / aids: Oscilloscope with 10:1 Test Probe, AF Generator, Digital Voltmeter, Test Cassette (HiFi).
Service work after changing the IO Board, the Tape Drum / Headwheel or the IC7400: Adjustment no. 1, 2
Adjustment
1. FM Envelope Oscilloscope: ............................................................. MP
R3485 Play back the test cassette (HiFi).
(FME)
2. Audio Envelope
Audio generator, 1kHz, 400mV
Call up the Service Function with the remote control:
– Press button "CODE" repeatedly until "CODE ----" appears on the
display.
– Enter 4 9 3 4 in this order and confirm with button G.
– Press button "CODE". Enter the figures 6 1 in this order and
confirm with "CODE". The message "ADJUST" appears on the
display.
Digital Voltmeter: ....................................................... MP
Left Channel,
R3408
(AEL)
Right Channel, Digital Voltmeter: ....................................................... MP
R3410
(AER)
5.2 IO Board – Standard Sound
Test equipment / aids: Oscilloscope with 10:1 Test Probe, AF Generator, AF Millivoltmeter, Branded Cassette.
Service work after changing the Family Board or the RP-Head: Adjustment no. 1, 2
Adjustment
1. Bias, Oscilloscope: ............................................................. MP
R3645 Record
(BIAS)
1.1 Frequency – Feed in a 5mV
Response generator at the audio inputs
– Record a 400Hz and 8kHz audio signal for approx. 1 minute
each, then replay this recording.
– AF millivoltmeter (oscilloscope) to EURO-AV socket contact
1/3 or Audio
2. Playback Level Audio generator 333Hz / 0.4V
HiFi recording (approx 1 min.).
Rewind to the start of this recording.
Call up the Service Function with the remote control:
– Press button "CODE" repeatedly until "CODE ----" appears on the
display.
– Enter 4 9 3 4 in this order and confirm with button G.

6. Teletext "DOS" (VT)

Test equipment / aids: Two-channel Oscilloscope with 1:1 Test Probes.
Service work after changing the components F1001/C2011: Adjustment no. 1
Adjustment
1. H/2-Sync Oscilloscope, channel 1: ..................... IC7080-(10), MP
Adjustment, F1001 Channel 2: ............................................. IC7080-(7), MP
Trigger: .......................................... channel 2, negative edge
Feed in a HF-signal (PAL) / Record or EE-mode without
Teletext.
3 - 6
Preparation
: ................ Audio
rms
Preparation
(14mV ) audio signal from the audio
rms pp
L / R.
L / R.
: .................. Audio
rms
Preparation
GV 64 ..., GV 65 ..., GV 66 ..., SE 6106 HiFi
Adjustment Procedure
22
With R3485 adjust the voltage according to the oscillogram
(FME)
below.
5ms/cm
L / R
23
With R3408 set the dc voltage to 1.4V.
(AEL)
24 With R3410 set the dc voltage to 1.4V.
(AER)
Terminate the Service Function by pressing button A or by
disconnecting the VCR from the mains.
Adjustment Procedure
25
With R3645 change the voltage between 22V
(BIAS)
62V to obtain a linear frequency response.
pp
The voltage ratio of 400Hz to 8kHz must not be higher than
1:0.7 and 0.7:1 respectively (±3dB). If the ratio exceeds these
limits, the bias must be altered as follows:
to increase the playback level at 8kHz: reduce "BIAS".
to reduce the playback level at 8kHz: increase"BIAS".
Press button "CODE". Enter the figures 5 8 in this order and confirm
L / R
with "CODE". The message "ADJUST" appears on the display.
On successful completion of this adjustment the display shows
"READY".
If the voltage difference between HiFi and Standard Sound is
more than ±1dB after this adjustment, the message "ERROR" is
indicated on the display. Cause: Preparation, video cassette or
technical defect in the Standard Sound section.
Terminate the Service Function by pressing button A or by
disconnecting the VCR from the mains.
Adjustment Procedure
12
With F1001 set the time interval between the middle of the
11
pulse H/2-SYNC (IC7080-(7)) and the trailing edge of SYNC
∆ µ
(IC7080-(10)) to t = 32 s
IC7080-(10)
IC7080-(7)
3.6V
and
pp
± µ
10 s.
∆t
64µs
GRUNDIG Service