TVR 3735…, TVR 3740…, TVR 5540…
Allgemeiner Teil / General Section
GRUNDIG Service
5
Service Instructions
1. Disassembly Instructions
1.1 Rear of the Cabinet
– Undo 4 screws
A
(Fig. 1, example TVR3740).
– Remove the rear of the cabinet.
1.2 Power Chassis
– Undo screw
B
and 2 screws
C
(Fig. 2).
– Slide the power chassis towards the rear of the TVR and lift it out.
– Unplug the connections if necessary.
Safety Note
– Always use an isolating transformer when carrying out repairs.
1.3 Plug-in Unit
– Unplug the connectors on the power chassis (P405, P406, P805)
and on the picture tube panel (P901) and untie the cables (Fig. 2).
– Disengage the catch
D
on the bottom of the TVR (Fig. 3).
– Slide the plug-in unit towards the back to gain access to 2 screws
E
(on the left and right, Fig. 4).
– Detach the connector (Fig. 7, PF03) on the keyboard control unit.
– Undo 2 screws
E
,
F
,
G
(on the left and right) each (Fig. 4).
– Lift the top of the plug-in unit (metal screening and power chassis)
and remove the plug-in unit (signal chassis and drive mechanism)
towards the back.
Service Position: see Fig. 5
– It is not possible to connect the loudspeaker in this service position.
Fitting Instruction:
– Before sliding in the plug-in unit from the rear side open the cassette
lid so that the cassette lid opener is correctly positioned in front of the
cassette lid.
1.3.1 Drive Mechanism
– Undo the screws
I
,
J
,
K
,
L
(Fig. 6).
– Remove the heat sink
M
(Fig. 6).
– Detach the connectors (Fig. 6, PAN01 / PAY01 / PAY02 / PAY03).
– Remove the drive mechanism carefully.
1.3.2 Signal Chassis
– Detach the connectors (Fig. 7, PF01 / PF02) on the keyboard control
unit.
– Undo screws
N
(Fig. 6).
– Disengage the catches
O
(Fig. 6).
– Take the signal chassis out of the mounting frame.
1.3.3 Keyboard Control Unit
– Detach the connectors (Fig. 7, PF01 / PF02 / PF03).
– Disengage the catches
P
(Fig. 7).
– Remove the keyboard control unit.
2. Important Mains Cable Strain Relief
When re-assembling the TVR, the mains cable has to be locked into
the bottom of the cabinet by means of the traction relief as shown in
Fig. 8 and laid out on the rear of the cabinet as shown in Fig. 9.
3. Important Chassis Connections!
When re-assembling the TVR take care of the chassis connections of
the individual components (for example Fig. 10/11).
4. Carrying out Measurements
When making measurements on semi-conductors with an oscillo-
scope, ensure that the test probe is set to 10:1 dividing factor. Further,
please note that if the previous measurement was made on an AC
input, the coupling capacitor in the oscilloscope will be charged.
Discharge via the item being checked can damage components.
5. Measured Values and Oscillograms
The measured values given in the circuit diagrams and oscillograms
are approximates!
Fig. 5
Fig. 6
Fig. 7
PAY03
PAN01
PAY02
PAY01
N
L
M
J
K
I
PF02
PF01
PF03
P
Fig. 8
O
O
Fig. 9
