Philips MCM720, Service Manual

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LAYOUT DIAGRAM - TUNER BOARD
98MHz
Waverange Input frequency Input Tuned to Adjust Output Scope/Voltmeter
VARICAP ALIGNMENT
FM - VCO
FM RF (channel separation)
AM IF
AM RF 3)
108MHz
87.5MHz
check
check
8V 1.2V
1.6V 0.5V
8V 0.2V
6.9V 0.2V
1.1V 0.4V
152kHz 1kHz
1) 98MHz 3142
198kHz 3 0 1 5 z H k 8 9 1
5111
FM
87.5 - 108MHz
(50kHz grid)
1602kHz
531kHz
5123
check
MW
531 - 1602kHz
(9kHz grid)
8V 0.2V
1.1V 0.4V
279kHz
153kHz
5122
check
LW
153 - 279kHz
(3kHz grid)
FM
FM
LW
558kHz 558kHz
1494kHz
5102
6 0 1 2 z H k 4 9 4 1
MW
MW
98MHz, 1mV
continuous wave
98MHz, 1mV
90% Left + 9% pilot
mod=1kHz
IF coil
inside
FM frontend
1110
1
3
5
5
A
FM - IF
0mV 3mV 5119
FM
10.7MHz, 45mV
continuous wave
2 D
right channel min.
4 A
0mV 2mV 5114 2
C
Repeat
C
5112
1) If sensitivity of frequency counter is too low adjust to max. channel separation
(input signal: stereo left 90% + 9%, adjust output on right channel to minimum)
2) RC network serves for damping the IF-filter while adjusting the other one.
3) For AM RF adjustments the original frame antenna has to be used!
TUNER ADJUSTMENT TABLE
( ECO6 Cenelec FM/MW - and FM/MW/LW - versions with AM-frame aerial )
max.
symmetric
fo
max.
symmetric
fo
ECO6 Sys Cenelec, 190599
B
f = 30kHz
V
RF
as low as
possible
MW has to be aligned before LW.
3-band
2-band
Note: The FM-frontend unit has already been adjusted by the factory
and needs therefore no further adjustments for service purposes.
2141
shortcircuit
to block AFC
21
IC 7101
see
remark 2)
220R
100nF
36
IC 7101
220R
100nF
40
IC 7101
450kHz
connect pin 6 of
IC 7101 (AM Osc.)
with 3.3k to Vcc
AM AFC
MW
continuous wave
V
RF
= 2mV
f = 10kHz
V
RF
= 0.5mV
(as low as
possible)
Use Service Testprogram. By selecting the TUNER TEST test frequencies will be stored as preset frequencies automatically.
AM FRAME AERIAL
FM 75
FM F
R
ONTEND
Birdy Filter
ECO6 Sys-Cenelec, layout stage .8, 200803
1101 B5
1102 B5
1103 C5
1110 B4
1120 A4
1130 A5
1131 C5
1132 A4
2106 B4
2107 B3
2128 A3
2129 B3
2133 C1
2138 B1
2144 B1
2162 A4
2191 B4
3142 C2
5102 C4
5103 C4
5109 B3
5110 A2
5111 A3
5112 A2
5114 A2
5115 C2
5119 B2
5121 B2
5122 C3
5123 C3
7104 C4
7105 C5
7112 B1
9101 A2
9102 B2
9103 A1
9104 B1
9105 B1
9106 B1
9107 B4
9108 B3
9109 C2
9110 A4
9111 A3
TUNER BOARD ECO6 Systems - Cenelec /
componentside view
B
A