Grundig GV 900 SV/1 Manuel De Service page 41

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