Kenwood T-91 User manual

COMPUTER CONTROLLED AM/FM STEREO
SYNTHESIZER TUNER ‘<= NAVLOl@) BD)
T-91/91L
SERVICE MANUAL
© 1987-10 PRINTED IN JAPAN
tom bacicr-ten elem (©) m-401c10)
4329
Dressing plate
(BO3-2324-04)
Panel*
Metallic
cabinet"
(A20-)
{AO
1-)
KENWOOD
a
Foot
(JO2-0174-04) x 4
Phono
jack
(2P)
Slide
switch’
(E13-02
17-05)
(S31-2115-05)
Screw
terminal
board*
AC
outlet
*
(E20-) (E03-)
B Power cord bushing
(J42-0083-05)
H AC power cord”
Slide
switch*
Miniature
phone
jack
(E30-)
(S31-2075-05) x 3 (E11-0168-05)
* Refer to parts list on page 46.
Photo is T-91.
4304

T-91/91L
CONTENTS
DISASSEMBLY FOR REPAIR
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CIRCUIT DESCRIPTION
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Caution
© Always connect the power cord of the tuner to an UNSWITCHED power outlet of the amplifier. If it is connected to a
SWITCHED outlet, system power cannot be turned on at once.
DISASSEMBLY FOR REPAIR
(Remove the metallic cabinet before proceeding to the
following.)
1. Remove the 3 screws holding the front panel and
sub-panel ass’y to the bottom (@).
2. Disengage the 3 lugs holding the front panel to the
sub-panel ass’y from the upper sideg®). and remove the
front panel in the direction of the arrow.
3. Disengage the lug behind the sub-panel ass’y and
remove the Power Switch Board (X14-) (C/3) (@).
4. Disengage the 4 lugs behind the sub-panel ass’y and
remove the Control Switch Board (X14-) (B/3) (@).
5. Remove the 5 screws holding the Tuner Unit (X05-
3410-10) and Display Unit (X14-22 10-11) (A/3) to the
chassis (@).
6. Remove the 3 screws holding the rear panel to the
chassis (@).
7. Without separating the Tuner Unit (X05-) and Display
Unit (X17 4-) (A/3). remove these PC boards and the rear
panel together in the direction of the arrow (@). During
this, pay special attention not to hit the top right
projection of the FL indicator tube against the sub-panel
ass'y or any other part (@).
(Caution for assembly}
8. When attaching the FL indicator tube to the sub-panel
ass’y, be careful of the lugs on the sub-panel ass’y (@).
9. When attaching the rear panel to the chassis, be sure
to engage the 3 lugs on the rear pane! with the dented
sections on the chassis (@).

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CIRCUIT DESCRIPTION
Function of components
Tuner unit (X05-3410-10)
Component
Purpose, Function
Operation,
Condition,
Interchangeability
IC1 (LA1265)
FM/AM
system
IC
FM
IF
amplification,
detection
and
control.
AM
MIX,
IF
amplifica-
tion and detection.
IC2 (AN7470)
IC3 (LM7001)
MPX IC MPX demodulation.
Frequency synthesizer PLL IC PLL synthesizer.
FM IF amplifier 10.7 MHz amplifier.
L.P.F. LPF for the PLL.
LPF switching Time-constant switching during LW reception.
FM-AM switching IC1 mode switching. OFF during AM reception.
LPF control Q4 control, OFF for LW reception.
AM RF switching Electronic RF switching for LW and MW.
AM OSC switching Electronic OSC switching for LW and MW.
Buffer Impedance conversion.
Inverter amplifier Auto Stop control
Q13,14 Tuner band switching FM/MW/LW band switching
Q17,18
Q19
Q20
Q22
Q23
Q15,16 Mute control Operates during function switching
Operates during function switching
Power control Power ON/OFF control.
Mute switching Activates muting during function switching.
Constant voltage Regulation of +5V.
Constant voltage CE control, regulation of +5V.
Tuner band switching FM/MW/LW band switching.

T-91/91L
CIRCUIT DESCRIPTION
Display unit (X14-2210-11)
Component Purpose, Function Operation, Condition, Interchangeability
2108)
FM-AM channel space switching, or LW channel switching.
Q1
Switching between 20 ch presets and 12 ch presets, station name
switching.
zi Channel switching
Q2 Preset switching
Q3 FIP driver FIP display driver.
a4 Control Control of Q3, based on signals from the microprocessor.
FIP control
0
fos [raver ——SSSS*d TNO
[oo [meer anpifer | Restconroi__—
Front-end unit (X86-1040-10): T-91
fox tmnerPSCSCSCSCSCSCSSSCSCSCSCSCSCS
OSC buffer
Front-end unit (X86-1052-70): T-91L
Purpose, Function Operation, Condition, Interchangeability
RF amplifier
Tuned buffer
Q1
Q2
Q3
Q4
Q5

T-91/91L
CIRCUIT DESCRIPTION
1C1: CXP5016-210S (X14-2210-10)
Microprocessor
Key matrix connection i ®
SCAND 4 ScANZ <SCINT
5V
NC
RESET
} 4194304MHz CRYSTAL
SERIAL DATA
NC
28 5V
FL 1G
FL 2G
FL 3G
KEY SCANO
FL 4G
KEY SCAN 1 GRID
FL 5G
15 FL 6G
KSCAN3 K SCAN2 KSCAN] K-SCANO
16 FL 7G
K: RETURN ©.
TV BOTH 17 FL 8G
TV MAIN TB/S1S Fl a
MONO T9si4 FL b
VHF H T10/$13 Fl c
PLL DATA TS12 Fld
PLL CLOCK 1121811 Fle
PLL LATCH TI3IS 10
KEY SCAN 4
T4IS9
POWER T15/S8
FL SEGMENT
MUTING $7
BILINGUAL sé
NC $5
so $4
TEST $3
SERIAL DATA
SERIAL BUSY
be ij GNO
*T-31 0 eeT-91L
Functions of diodes and switches (0: Without diode, 1: With diode)
Destination Band Receiving Frequency jInter-Channel] Intermediate Auto
BO Range Frequency Tuning
Frequency | Terminal
FM
87.5MHz-108.0MHz +10.7MHz |
631kHz-1602kHz kHz
87.5MHz-108.0MHz | 50kHz
53 1kHz-1602kHz
18 3kHz-28 1kHz
87.5MHz-108.0MHz
53 1kHz-1602kHz
Lw
“ The T-91 Types M,U and UE are modified into Types E1 or K by switching the inter-channel space with the CHANNEL
SPACE SW (S31) on the rear panel and by adding a diode (1$$133) for BAND 2.
Before switching, turn the AC off (by pulling out the power plug), switch the switch, and turn AC on again.
If the AC power is left ON, switching the switch does not change the destination.
** With the T-91L (France made), a diode (ISS133) is added for BAND 1 to perform manual tuning in LW only.
ie)

T-91/91L
CIRCUIT DESCRIPTION
Terminal description
Symbol Name | 1/0 | H/L | Function
Not used. On the PC board, make it capable of being pulled up using a registor.
Backup (AC OFF) detection terminal. H: AC ON
When L level is detected, the backup condition is set and the clock is stopped. L: AC OFF
Note: The rise from L to H shall be faster than the rise of reset.
| 0 |
moo
| 1 | — | Notused. Pull down with the GND or a resistor.
paieg
po | H |
KEY Co Key return input. H: AC ON
All pulled down (10k to 100k) L: AC OFF
1215 PCO ~ PC3 | KEY SCANO~ 3 Key scanning signals.
H
a =
TV bilingual multiplexed audio mode control terminals.
H Mono/Auto stereo contro} terminal.
Permanently L during TV bilingual reception.
Band selection control terminal.
Selects the band by the combination with BO2
and BO3 © of PLLIC.
O | H/L
PLL DATA PLLIC data output. Connected to LM7001 DATA © terminal.
PLL CLOCK Race PLL IC clock output. Connected to LM7001 CLK@ terminal.
fF 22, Pe2 ss PLLLATCH [ O | H [| PLLIC latch output, Connected to LM7001 CE@ terminal.
KEY SCAN 4 pepe Key scanning signal
: H: POWER ON
POWER Relay control terminal. L- POWER OFE
‘ : ae : H: MUTE ON
PBI MUTING ee Muting control during band switching, frequency scans: etc. L: MUTE OFF
a
NE Not used. Pull down with a resistor.
: : : H: TUNE
28 Stop signal input for auto tuning. L: NO SIGNAL
oe H: NORMAL
Test mode setting input. L: TEST
w
BW] Wl wl a) Ww] Ww] Ww] ao N nN NR]
OPN) Olay as —-}o] © NN a oS
System control DATA output.
System control BUSY input/output.
GND terminal.
FL segment drive terminal (FL segment terminal p)
Nm
Ww
n oO
| =|=|=|={=/=[=|={=|=[=|=[=[=|=[=[1|=|=| - ae
—
FL segment drive terminal (FL segment terminal 0)
FL segment drive terminal (FL segment terminal n)
nNIn WIN
3/53 O};O FL segment drive terminal (FL segment terminal m)
n oS
FL segment drive terminal (FL segment terminal |)
wn oi ~~
FL segment drive terminal (FL segment terminal k)
39 FL segment drive terminal (FL segment terminal j)
40 $7 FL segment drive terminal (FL segment terminal i)
41 T15/S8 FL segment drive terminal (FL segment terminal h)
T14/S9 FL segment drive terminal (FL segment terminal g)
T13/S10 FL segment drive terminal (FL segment terminal f)
T12/811
T11/S12
T10/S13
ee
FL segment drive terminal (FL segment terminal e)
FL segment drive terminal (FL segment terminal d)}
j
i
h
9g
f
e
d
c FL segment drive terminal (FL segment terminal c)
b
FL segment drive terminat (FL segment terminal b)
FL segment drive terminal (FL segment terminal a)

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H_[ AL grid dive terminal FL ghd terminal 76)
FL grid drive terminal (FL grid terminal 3G)
FL grid drive terminal (FL grid terminal 2G)
FL grid drive terminal (FL grid terminal 1G)
Not used. Connected to VoD.
System control DATA input.
Clock oscillator terminals. X'tal 4.194304MHz.
H: NORMAL
L: RESET
Not used. Open (On the PC board, make it capable of being pulled up.).
+B terminal (5V).
Reset signal input.
Pa |
=
[ [Five power supp e286.
a
=
ee
FL1:FIP12PM7 (X14-2210-11)
Fluorescent indicator tube
Terminal connection
p h A4
procram | 4] [2] off Time || auto
A5
[ STEREO } TUNED
ik)
~~
‘orm
ae
ae
WAL INA Ram of tg fo) fly ®/ =
°
ON TIME
aie
[WA
a I
MA aly fla fs If] 9 fo Jo fi »
VAM | AMBER nf fal jel leffal Lil We
x 6 x STR A
rs bee vee
8G 7G 6G 5G 4G 3G 2G 1G
* Function only in T-91, x Function only in T-91L
**%* Does not function
Pin No. 6 7 8 9 11 12
Electrode 3 i 8G P{j) P(n) 7G Plo) Pt{k) P(m) 6G P(l)
Pin No. 16 17 19 202] 22 23 24 25 26 27 28 29 30 31 32
Becton 5G P(n) P(k) Pi) P(j) 4G 4G 3G Po) P(p) P(A5)P(A4) 3G NP 2G P(A3)P(A2)P(Al) P(h)
Pin No. 33 34 35 36 37 38 39 40 41 42 43 44
Electrode P(d) 2G Pe) Plc) 1G P(g) P(f) P(b) 1G Pla) F F
Notes F: Filament P: Anode G: Grid NP: No pin
Caution: Pins 3 and 16 (isegment), pins 5 and 17 (j segment), pins 6 and 14 (n segment), pins 8 and 22 (o segment) and pins
9 and 15 (k segment) are not internally connected to each other.
Please connect each pair externally (by means of a PC board, for example).

T-91/91L
CIRCUIT DESCRIPTION
IC3: LM7001 (X05-3410-10)
PLL frequency synthesizer
Block diagram
syc Phase Detector
Charge Pump
XIN o Reference Divider
il
XOUT o
J
ie
:
FMIN
o
|
>o
ose
/\
Programable
Divider
lie
wobe
:
el
i
AMIN
o
>
16
ves
Shift Register Latch
o PD1
o PD2
Terminal description
Pin name Function
XOUT
Crystal oscillator (7.2 MHz).
Data input.
Clock for controller (400 kHz).
Band data output.
BO1 can be used as a time base output
(8 Hz)
Local oscillator signal input
Power supply.
VDD2 for back-up.
Charge pump output
Power supply.

CIRCUIT DESCRIPTION
t1>10us
Dota Input 1e>,10us
tititt
CL (PIN@)
DATA (PIN®) -
CE (PIN@)
INTERNAL DATA
<Input at DO
fooTo1 [o2[o3[ 04] os [6 [o7Tos[os] 010 [011 [12 [ 013 [tof 71 [80] 81 | 82] 78] RO] RI] R2 |
(1) DO(LSB)~D13(MSB): Dividing ratio data
FMIN uses DO-D13 and AMIN uses D4-D13.
[Do | D1 | 2 | 03] D4 | 05 | D6 | D7 | D8 D9] O10 | 011 | 012 | 013 |
1 0 1 0 0 0 0 90 90 1 0 1 1 1 -> FMIN dividing ratio= 14853
LSB MSB
Xx -&®& X X 0 0 0 0 0 1 0 1 1 1 + AMIN dividing ratio=928
LSB MSB
(2) TO, T1 For LSI checking (0,0):
(3) BO~B2: Band data
Time base data
$ : Determined by RO1~R2
X : don’t care.
TB: 8 Hz
(4) RO~R2: Reference frequency data
(5) S: Divider selection data
‘T°: FMIN, ‘0’ : AMIN
10