Fisher FM-891 User manual

SERVICE
MANUAL
P|
FISHER
LW/MW/FM
STEREO
EM-801
SYNTHESIZER TUNER
(EUROPE)
125 962 42
This
service
manual
is
prepared
for
Model
FM-891.
As
only
the
components
in
the
chart
below
differ,
refer
to
the
service
manual
FM-890
(WM-17160)
for
other
components.
L
m8
ae
1
3-9415-10300
Bag
Polyethylene
ae
131-6-1169-16823
131-6-1169-16837
Box
Corrugate-Exp.
et
1
142-6-4119-32890
142-6-4119-33425
Explanatory
Booklet
CABINET
131-2-1601-85203
131-2-1601-85209
Knob
(Power)
5
141-0-1129-17901
141-0-1129-17902
Cabinet
Front
Assy
141-2-1129-39701
141-2-1449-61246
141-2-1129-39702
=
141-2-1449-61 298 Plate Front
141-2-1449-70701
1
1
1
141-2-1449-70702 Plate Decorate 1
Cabinet Front
Add
this
sheet
to
the
Model
FM-890
Service
Manual
(WM-17160).
REFERENCE No. WM-19685
FISHER Hi-Fi Europa Vertriebs GmbH
Stahigruberring 4 Tel: [phone]
8000
Munchen
82
Tlx:
524033
February/'87/2,000/K
Printed
inJapan

Bees
125 962 40
soe

CONTENTS
FUnCUONAal BIOCK DIAGlaM: ¢ssicvadeesiccenntatiosecueeiieteddesasctacsaseteaeniaies Seas 2
SDSCHICALIONS 42 hctreese caret pusen teresa epee tian ndees nepeeimenaandeouscuswssansea bess 3
Cabinet & Chassis Exploded View ........ ccc ccc ccc cece cece e eter eet een eeeeeneeenenaes 4
Cabinet &-Chassis Pats LiSt scocicsncrk dca bennce Chamtiandsuetaieeaeueiseosareew ieee 5
Tuner P.C.Board Layout Alignment Points (Top View) ................c cece cence eens 6
AM FUNC AUQNMONt asi tucconteliceadietieseon ides deena see el or ecar epsdanaacitweeagues 7
HEM TUNer AlIQAMONt otteissnnscuasesdetsacnvedacawertuehs Goudocansiaeadesmmnciuniananks 8
IC Equivalent Circuit & Block Diagram ...............c. cece eee ees eee 9,10,11,12,13
P.C.Board Parts List ...... be eich casas astec evens Seep anis nee emasaesoecee Tue oae 14,15,16,17,18
Preset Switch P.C.Board (Bottom VieW) ...........:ecceceecneeneeee teen eeeeeeeenenes 19
‘Antenna P.C.Board (Bottom View) ..........c.ccccseceeceeeeeeeeeeeeeeeeeeeeneeaeeneaees 19
Remote Control Input P.C.Board (Bottom View) ..............ccecceeceeeseeteeneeeeeees 19
Band Switch P.C.Board (Bottom VieW) ...........00cceecceecccecceeececevaceeeeneeeennes 20
Meter LED P.C.Board (Bottom View) .............seeecee eee eeee ee te eee e eee e teen nena: 20
Power Switch P.C.Board (Bottom View) ............ccecccceeeeseeee eens Sg ae eae 20
Schematic: Diagram orcacsuasncrcaun.ns acs uncadave rues Sande weveea aoe ae ieee: 21,22
Tuner Printed Circuit Board (Bottom View) ............0cccceecceceeeeeeeeeeueeaeees 23,24
Front End Schematic Diagram ..............0ceceeneee eee ee eee tent eee se ee ea ease eee eee: 25
Semiconductor Lead Identification .............. 0. cee eee eee eee eee eee eee ee een een es 26,27
FUNCTIONAL BLOCK DIAGRAM
FM Front End
EM Four tuned alld
Varactor Diode Left
oe Ll me iL | FM-IF/DET MPX .
€B T We Ty LA1235 LA3400
Dual
Gate
,
;
.
MOS FET Differential Double IF Amp. Right
WD) rg
LA6458
AM
Loop Antenna
AM IF/DET
LA1245
Level Meter
LB1403
- Function
. Control
LW
Remote
Control
Terminal
TC9303AN 4 Key Matrix Z Remote Control ; :
-001 K—] Transistor K——) MicroProcessor K—————_—_—_——_ 0
Z Switch TMP4270
| | 15.6V 5.6V —24V
c &
~|1AMOSC Control LSI
PLL
resi7ip,
LA6458
7 coc
thet etal Lat Lt ht
: : Band/Preset
Digitron Display Control Constant Voltage
Regulator
Front Panel LA5666

SPECIFICATIONS
FM-890
FM SECTION
Usable Sensitivity
1uV
_ Stereo BuV
46 dB Quieting Sensitivity
Mono SuUV
30KV
Signal-to-Noise Ratio
70 dB
Stereo 67 dB
Capture Ratio 1.0 dB
Alt. Channel Selectivity (£300 kHz) 60 dB
Image Response Ratio 75 dB
Mono
| Spurious Response Ratio 80 dB
IF Response Ratio 110dB
AM Suppression Ratio 60 dB
Total Harmonic Distortion at 46 dB Quieting
Mono 0.3%
Stereo 0.4%
Total Harmonic Distortion at 65 dBf (IF Bandwidth Normal)
Mono (100 Hz/1 kHz/6 kHz) 0.05/0.05/0.1 %
Stereo (100 Hz/1 kHz/6 kHz) 0.1/0.1/0.1 %
Stereo Separation
(100 Hz/1 kHz/10 kHz) 45/45/35 dB
Sub-Carrier Rejection (19 kHz/38 kHz) 65/75 dB
Audio Frequency Response .
(20 Hz — 15 kHz) +1.0dB
AM SECTION MW LW
Usable Sensitivity 600 uV/m 1 mV/m
Signal-to-Noise Ratio 55 dB 55 dB
GENERAL
Power Requirements (50 Hz) 110/220 V AC
Power Consumption 12 Watts
Dimensions (W x H x D) | 440 x57 x 280 mm
Weight (approx.) 2.8kg
Because its products are subject to continuous improvement, Fisher Corporation reserves the right to modify
product designs and specifications without notice and without incurring any obligation.
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CABINET & CHASSIS EXPLODED VIEW
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Ref.
No. Part No.
CABINET & CHASSIS PARTS LIST
Description
PACKING PARTS LIST
3-9415-10300
131 -6-1169-16823
131 -6-3009-35610
131 -6-3009-35620
131 -6-3069-16350
131 -6-4559-11200
131-6-9459-00300
141-6-2519-11022
141 -6-2519-22290
Bag Polyethylene
Box Corrugate-Exp.
Pad (Right)
Pad (Left)
Patching Sheet
Serial No. Sheet
Rubber Band
Poly Cover 110 x 220
Sheet Polyethylene
ACCESSORIES PARTS LIST
131-0-4012-00180
131 -6-2719-10401
141-2-1729-00500
142-6-4119-32890
FM Antanna Assy
Bag Fan
Holder Antenna
Explanatory Booklet
CABINET & CHASSIS PARTS LIST
4-2379-21520
131 -6-4559-11200
1 131 -2-1601 -85203
2 141-0-1619-36600
141-2-1659-75200
141-2-2629-10100
3 131-2-4219-17100
4 131 -2-6308-23502
5 141-0-1129-17901
131 -2-1601 -94800
131 -2-4208-49700
141-0-1619-36100
141-2-1129-39701
141-2-1319-45800
141-2-1449-61246
141-2-1449-70701
6 141-0-1149-14700
141 -2-1149-48900
141-2-1439-16600
141-2-1439-16800
7 141-2-1119-93300
8 131 -2-4221 -00600
- 9 131 -2-1801-14100
10 131-2-7104-00500
11 131 -2-6111-14200
12 141-2-1219-36402
13 141-2-1259-09500
14 141 -2-2149-27200
15 141-2-3119-27100
16 141-2-3229-43100
17 141 -2-3849-05400
18 141-2-4359-40700
19 131 -2-361 4-22900
20 131 -2-5205-27401
21 131 -2-3614-18700
Terminal Lug
Serial No. Sheet
Knob (Power)
Knob Assy (Function)
Knob Cap
Holder Knob
Shaft
Filter (Clear)
Cabinet Front Assy
Knob (Touch Switch)
Spacer
Knob Assy (Tact)
Cabinet Front
Window
Plate Front
Plate Decorate
Mount Screen Assy
Mount Screen
Screen LED
Filter Digitron
Cover
Rivet
Leg
Plate Pad Switch
Bushing (4N-4)
Panel Rear
Bottom Cover
Panel Front
Chassis
Plate Shield
Holder Antenna
Plate Sever
Mount P.C.B.
Cushion
Mount P.C.B.
Q’ty tae Part No. Description
ELECTRICAL PARTS LIST
1 25 141-0-1939-17690 Tuner P.C.B. Assy
1 26 141-0-1939-17700 Band Switch P.C.B. Assy
1 27 141-0-1939-17710 Preset Switch P.C.B. Assy
1 28 141-0-1939-17720 Antenna P.C.B. Assy
1 29 141-0-1939-17730 Power Switch P.C.B. Assy
2 30 141-0-1939-17740 Meter LED P.C.B. Assy
1 31 141-0-1939-17750 Remote Control Input P.C.B. Assy
1 32 4-2369-74581 Plug Cord RCA (Output)
1 33 A\ 4-2432-00502 Power Cord
34 A\ 4-2512-32220 Power Trans
35 4-2579-72420 Loop Antenna
36 4-6129-70713 Lamp
1 37 A\ 4-2312-02650 Switch Slide 3P (AC Selector) [SW1]
1
1
1 SCREW PARTS LIST
40 101-3-1303-00611 Screw, Pan Hd., +M3.0x6
44 143-3-1704-01011 Screw, Bind Hd. Tapping-B, +M4.0x10
42 143-3-1902-60811 Screw, Brazier Hd. Tapping-B, +M2.6x8
43 143-3-1902-60818 Screw, Brazier Hd. Tapping-B, +M2.6x8
— 44 143-3-1902-61011 Screw, Brazier Hd. Tapping-B, +M2.6x10
45 143-3-1903-00611 Screw, Brazier Hd. Tapping-B, +M3.0x6
46 143-3-1903-00618 Screw, Brazier Hd. Tapping-B, +M3.0x6
47 143-3-1903-00818 Screw, Brazier Hd. Tapping-B, +M3.0x8
48 143-3-1903-01011 Screw, Brazier Hd. Tapping-B, +M3.0x10
49 141-2-4219-38400 Screw, Bind Hd. Tapping-B, +M4.0x8 Sems
50 141-2-4219-33101 Screw, Bind Hd. Tapping-B, +M3.0x8 Sems
51 131-2-4201-25302 Screw, Sems +3.0x14
52 _ 101-3-1303-00818 Screw, Pan Hd., +M3.0x8
53 143-3-1302-60811 Screw, Pan Hd. Tapping-B, +M2.6x8
54 131-2-4201-16700 Screw, Brazier Hd. Tapping-C, +M3.0x6
Ct CC4-7-3500-ZG00C Ceramic 0.047uF 50V +80,-20%
C2 CC1-0-2500-KE00C Ceramic 0.001MF 50V +10%
C3 CC4-7-3500-ZG00C Ceramic 0.047u4F 50V +80,-20%
NOTES:
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Q’ty
1. Parts order must contain Model Number, Part Number and
Description.
2. Ordering quantity of screws and resistors must be multiple of
10 pcs.
PRODUCT SAFETY NOTICE
Each precaution in this manual should be followed
during servicing. Components identified with the IEC
symbol A\ in the parts list and the schematic diagram
designate components in which safety can be of special
significance. When replacing a component identified
with A\, use only the replacement parts designated, or
parts with the same ratings of resistance, wattage or
voltage that are designated in the parts list in this manual.
Leakage-current or resistance measurements must be
made to determine that exposed parts are acceptably
insulated from the supply circuit before returning the
product to the customer.
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=R P.C.BOARD LAYOUT
MENT POINTS
(TOP VIEW)
3
Ant Birdie
Filter
DIGITRON
ADS MES SRN

AM TUNER ALIGNMENT
AM ALIGNMENT — FUNCTION switch to LW or MW position.
Maintain generator output as low as possible for suitable indication.
ITEM
GENERATOR
DIAL
SETTING
INDICATOR
|
PROCEDURE
1.
MW
RF
Do
not
connect
Front
Panel
Connect
DC
Volt-
|
Adjust
MW
OSC
Coil
(T6)
until
DC
FREQUENCY
|
generator.
DIGITAL
Counter
meter
to
Front
Voltmeter
reads
0.9V
+
0.02V.
COVER
Display
End
B2
terminal
ALIGNMENT
Set
to 522kHz.
and
ground
lead
(522kHz) to chassis.
DIGITAL Counter
Display
Set to 1611KHz.
Adjust Trimmer Condenser TC3
(OSC) until DC Voltmeter reads
8.0V+0.1V.
Same as above.
2 Same as above.
(1611kHz)
Note:
Repeat
the
adjustments
in
Items
1
and
2.
Then,
confirm
that
each
voltage
becomes
0.9V
to
8.0V
at
receving
frequen-
cy
of
522kHz
to
1611KkHz.
3.
LW
RF
Do
not
connect
Front
Panel
Connect
DC
Volt-
|
Adjust
LW
OSC
Coil
(T7)
until
DC
FREQUENCY
|
generator.
DIGITAL
Counter
meter
to
Front
Voltmeter
reads
1.2V
+
0.05V.
COVER
Display
End
B2
terminal
ALIGNMENT
Set
to
153kHz.
and
ground
lead
(153kHz) to chassis.
4.
Same
as
above.
DIGITAL
Counter
Same
as
above.
Adjust
Trimmer
Condenser
TC4
(360kHz)
Display
(OSC)
until
DC
Voltmeter
reads
Set
to
360KHz.
8.0V+0.1V.
Note:
Repeat
the
adjustments
in
Items
3
and
4.
Then,
confirm
that
each
voltage
becomes
1.2V
to
8.0V
at
receving
frequen-
cy
of
153kKHz
to
360kHz.
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5. AMIF
ALIGNMENT
Adjust AM IFT (T5) for maximum
gain and best symmetry.
Keep signal low enough for
noise on responce.
Connect Radio IF
Genescope input
to TP5 and
ground lead to
chassis.
Position of
non-interference
DIGITAL Counter
Display
Set to 999KHz.
Connect 450kKHz Radio
IF Genescope output to
testpoint TP13 and
TP14 (ground).
Connect AC VTVM
and Oscilloscope
to TP9 or TP10
TUNER OUT.
6. MW RF
TRACKING
ALIGNMENT
(603kHz)
DIGITAL Counter
Display
Set to 603KHz.
Adjust MW Antenna Coil (T3) for
maximum gain output.
Connect Standard Loop
Antenna to output
terminal of AM RF
Signal Generator.
Place Test Loop
Antenna 60cm away
from Loop Antenna.
7. Generator Setting to DIGITAL Counter Adjust Trimmer Condenser TC1
(1404kHz)
603kKHz
or
1404kHz.
Display
(ANT)
for
maximum
gain
output.
_
Modulate
with
1kKHz
Set
to
1404kHz.
|
Same as above.
Note: Repeat the adjustments in Items 6 and 7. Then, confirm there is no tracking error.
(30 % modulation).
8. LW RF
TRACKING
ALIGNMENT
(160kHz)
DIGITAL Counter
Display
Set to 160KHz.
Connect AC VTVM | Adjust LW Antenna Coil (T4) for
and Oscilloscope maximum gain output.
to TP9 or TP10
TUNER OUT.
Same as above. |
Note: Repeat the adjustments in Items 8 and 9. Then, confirm there is no tracking error.
Change generator
setting to 160kKHz.
9
; DIGITAL Counter
(350kHz)
Display
Set to 350kKHz.
Change generator
setting to 350kHz.
Adjust Trimmer Condenser TC2
(ANT) for maximum gain output.
10. AMAUTO Change generator
STOP setting to 999kHz
SENSITIVITY jand output level to
ADJUSTMENT |57dB/m.
Set to 999KHz. Connect DC Volt- Adjust VR4 until DC Voltmeter
meter to TP7. reads 80mV, so that MANUAL/
AUTO Function works at 999kHz
on DIGITAL Counter Display.
Use a screwdriver with plastic grip for all adjustments.

EM
TUNER
ALIGNMENT
FM
ALIGNMENT
—
FUNCTION
switch
to
FM
STEREO
ITEM
GENERATOR
DIAL
SETTING
INDICATOR
|
PROCEDURE
Note:
The
EM
IF
circuit
utilizes
a
non-turnable
ceramic
filter
which
establishes
the
IF
bandpass.
To
insure
symmetrical
turning
and
selectivity,
the
IF
must
be
aligned
precisely
to
the
center
of
the
filter
bandpass,
rather
than
to
10.7MHz
as
in
conventional
LC
circuits.
Adjust
FM
IF
Trans
(T1),
so
that
S-curve
form
becomes
symmetrical.
Connect Radio IF
-Genescope input
to TP4 and ground
lead to chassis.
Use 1pF capacitor
in series with gene-
rator output lead.
Connect
10.7MHz
Radio
|
Position
of
IF
Genescope
output
to
|
non-interference.
testpoint
TP1
and
ground
lead
to
chassis.
Use
5pF
capacitor
in
series
with
generator
output
lead.
. FM IF
S-CURVE
ALIGNMENT
.
DETECTOR
Connect
FM
PF
signal
Front
Panel
Harmonic
Adjust
FM
IF
Trans
(T2)
for
ADJUST-
generator
througt
FM
DIGITAL
Counter
Distortion
Meter
minimum
gain
and
best
MENT
Dummy
Antenna
to
FM
Display
and
Oscilloscope
linearity.
(MINIMUM
Antenna
terminals.
to
TUNER
OUT.
Set to 98MHz.
T.H.D,)
Set
generator
output
-
|
level to 60dB at 98MHz
+ 2KHz.
Note:
Repeat
Items
2
until
optimum
alignment
is
reached.
Adjust VR1 until DC Voltmeter
reads OV + 20mV.
Press
the
UP/DOWN
button
and
Check
that
Auto
Stop
Function
works
at
98MHz
on
DIGITAL
Counter
Display.
. FM AUTO
STOP
SENSIVITY
ADJUST-
MENT
Same
as
above.
Same
as
above.
Connect
DC
Volt-
meter
to
TP2
and
TPS.
Set
generator
output
Same
as
above.
Scope
vertical
level to 18dB at 98MHz
+ 2kKHz.
input to TUNER
OUT.
Note:
Decrease
the
output
level
of
ATT
and
confirm
that
the
curve
form
disappears.Increase
the
output
level
of
ATT
again
and
confirm
that
the
input
level
meets
the
specifications
sufficiently
when
the
curve
form
has
appeared.
Set
Mode
Switch
(MONO/ST)
to
STEREO
and
adjust
VR2
until
the
received
curve
form
becomes
half
of
the
maximum
form.
. FM MUTING
LEVEL
ADJUST-
MENT
DIGITAL Counter Front Panel
Display SIGNAL
Set
to
98MHz.
STRENGTH
LED
Display.
Same
as
above.
Connect
DC
Volt-
meter
to
Front
End
AGC
terminal
and
ground.
Set
generator
output
Same
as
above.
Connect
AC
VTVM
level
to
60dB
at
98MHz
and
Oscilloscope
+
2kKHz.
|
to
TUNER
OUT.
Connect
FM
Stereo
SG
Connect
AC
VTVM
to
FM
Antenna
termi-
and
Oscilloscope
nals.19kHz
signal
ON.
to
RIGHT
TUNER
Main
channel,
sub
OUT.
channel signal ON
Apply 1000Hz signal
from LEFT channel.
Same
as
above
for
Connect
AC
VTVM
RIGHT
channel.
and
Oscilloscope
to
LEFT
TUNER
OUT.
Use
a
screwdriver
with
plastic
grip
for
all
adjustments.
Adjust
VR3
until
the
fifth
signal
LED
partly
lights
up.
. SIGNAL
LED METER
ADJUST-
MENT
Set generator output
level to 6OdB at 98MHz
+ 2KHz. —
Adjust
VR5
until
the
DC
Voltmeter
reads
2.0V+0.1V.
Set generator output
level to OdB at 98MHz
+ 2kHz.
. FM AGC
ADJUST-
MENT
Adjust VR7 for signal to nise
ratio.
. FM STEREO
SIGNAL
SEPARATION
CONTROL
Adjust
VR6
for
minimum
output.
—8-—
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IC EQUIVALENT CIRCUIT & BLOCK DIAGRAM
FM IF AMP IC LA 1235
Vcc
HW 8 9 10
corto Qa a ee Opn =O = Qe a ee = - 4
| |
| l
| wor | | ;
| TUNING WETER L—O>5 fete
| MUTING
l
7 d
QUAD DETUNING
ewe T= Te Te Tee
2
Q LEVEL QUAD O)7 AFC
/
DET.
DETECTOR
a:
10 I
CONTROL AMP C) 6 AF OUTPUT
METER SCHMITT MUTE
O54 !
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13 16 12 14
AM IF AMP IC LA 1245
BUFFER , SIGNAL
OUTPUT METER IFVcc OUTPUT ~~—s- IF GND
- MWANT. = RFGND RF Vcc
SIGNAL LED METER DRIVE IC LB 1403 N
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