GRUNDIG Service
3 - 9
k
GV 900…, GV 940…
Troubleshooting
englisch • English • anglais
Fuse F901 ok?
Power supply AT 5V ok?
Power supplies
AT45V, AT21V, AT12.6V,
AT-25V and fi/– ok?
High level at IC701-(1)?
IC701?
No Power
Primary side:
Check D910, D911, D912 und D913.
Replace F901, Q901, IC902 and R904.
Secondary side:
Check D9612, D9601, D9602, D9603,
D9604, D9607 and peripheral circuit
of secondary side.
Rectifier circuits?
Short-circuit on secondary side?
Peripheral circuit of Q9603?
Signal path POWER_FAIL_L?
Troubleshooting Diagram 1 – Power Supply
YES
YES
YES
NO
YES
NO
NO
NO
IC901 and peripheral circuit (IC9601,
C9613, R9608, R9609,
R9610, R9611)?
IC902 and peripheral circuit IC902-(9)?
Transfo T901?
Primary side and peripheral circuit
of Q901?
Troubleshooting Diagram 2 – Fluorescent Display
NO
NO
NO
YES
YES
YES
YES
NO
5V at IC801-(18)?
-25V at IC801-(16)?
Power supply STBY5V?
Power supply STBY-25V?
4MHz oscillator frequency at
IC801-(19, 20)?
Quartz FL801?
Filament voltage applied between
Pins (1/2) and (31/32) of the
fluorescent display tube?
Is there also negative voltage applied
between these pins and GND?
Power supply
F / Filament-?
D9910?
Cracks on fluorescent display tube?
IC801?
Fluorescent display fails to light up.
GB
Troubleshooting Diagrams
Troubleshooting Diagram 4 – Remote Control
No operation via remote control
Does remote control handset work?
Does "VCR" flash in the display?
Change remote control level.
5V at RMC801-(3)?
Low pulses at RMC801-(1)
when pressing a remote control button?
Low pulses at IC701-(5)?
IC701?
NO
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
Troubleshooting Diagram 3 – System Control
VCR cannot be switched on
from Standby.
Data signal applied to IC701-(15)?
Check all the paths between
IC801 and IC701.
NO
IC701-(13,94) High?
Voltage applied to IC701-(1, 36, 73)
Data, clock and control signals at IC801-(22…25)?
When pressing button
Å
is High
level at IC701-(94)?
IC701, Q9905, Q9906?
AT5V
Q703, Q704
IC701?
10V at Q9905-(B)?
Signal path from IC701-(94) via
Q9906 to Q9905?
9V at Q9905-(E)?
Power supply AT 12.6V?
Peripheral circuit of Q9905?
YES
YES
YES
NO
NO
6V at Q9908-(B)?
Signal path Q9905-(E) and Q9908-(B)?
5V at Q9908-(E)?
Power supply AT5V?
Peripheral circuit of Q9908?
Dry joints on the
Chassis Board?
S. / P.
IC201
4-26
IC202
4-26
IC651
4-25
IC701
4-22
IC702
4-21
IC703
4-22
IC704
4-22
IC705
4-22
IC801
4-21
IC901
4-28
IC902
4-28
IC1601
4-33
IC1602
4-29
IC1701
4-36
IC1801
4-22
IC1901
4-35
IC1951
4-35
IC2501
4-24
IC5301
4-31
IC6301
4-24
RMC801 4-21
Tuner
4-30
