Onkyo TX-7900 User manual

Ref. No. 3420
ONKYO
SERVICE
MANUAL
QUARTZ SYNTHESIZED
TUNER AMPLIFIER
MODEL TX-7900
MODEL TX-7920
Black and Silver models
SAFETY-RELATED COMPONENT WARNING! !
COMPONENTS IDENTIFIED BY MARK A ON
THE SCHEMATIC DIAGRAM AND IN THE PARTS
LIST ARE CRITICAL FOR RISK OF FIRE AND
ELECTRIC SHOCK. REPLACE THESE COMPO-
NENTS WITH ONKYO PARTS WHOSE PART
NUMBERS APPEAR AS SHOWN IN THIS
MANUAL.
MAKE LEAKAGE-CURRENT OR RESISTANCE
MEASUREMENTS TO DETERMINE THAT EXPOSED
PARTS ARE ACCEPTABLY INSULATED FROM
THE SUPPLY CIRCUIT BEFORE RETURNING
THE APPLIANCE TO THE CUSTOMER.
ONKYO
AUDIO COMPONENTS
TABLE OF CONTENTS
Specifications eee errr ee eee eee eee ee eee Tee eee eee eee ere Terre ree eee ere 2
Service procedures::+++i+sssssssstssesesesseeesseeseseeseserseeageeens 3
Exploded view Model TX-7920++:+++:+++s+sssesseseseeeeseeessseeneens 4
Parts Ist Model TX-7920 tse: wvesncwses ceracmmamninsaeennenee 5
Exploded view Model TX-7900++++++++++:ssess+sessesesseeereeesaeeens 6
Parts list Model ‘TX-7900 issssster<eomnns sane venwavanes senna canon cones 7
Block diagram Model TX-7920-++++1:+++ssessseerseeesseersese seeeees 8
Block diagram Model TX-7900-+++++:++1s+sessseerseseseeteseeeeeeeens 9
IC block diagram and descriptions::::::1++++sseeeseseeseeseerees 10
Packing view svrcessscessceeeseeessseeseessenseneeseesesescnesensereanneens 17
Adjustment procedures ree eee eee eee er errr) 18
Printed circuit board view from bottom side-+r+++++rrr + est+* 21
Schematic diagram
Model "P7920: sere: ose cwaes uedewvensaes eonnenamenaee eemaseeeninenl 23
Model TX: 7900» «sss sentecnnsaxonenen nonce dvtineanennasaerawargicaeenines 25
Printed circuit board-parts list
Model “TX. 7620 se2nesenses ary deanwians sccswansapanvagis narangianane gies sen 29
Model 1X. 20 0Gxrtceswens corweswaieaee dennwonatennigipien vpeiciirnay 9 tate wea 39
TX-7900/TX-7920

TX-7900/TX-7920
SPECIFICATIONS
AMPLIFIER SECTION
Power Output:
Dynamic Power Output:
Continuous Power Output:
Total Harmonic Distortion:
1M Distortion:
Damping Factor:
Frequency Response:
RIAA Deviation:
Sensitivity and Impedance:
Phono Overload:
Signal-to-Noise Ratio:
Tone Controls:
Muting:
LOUDNESS (—30dB):
TUNER SECTION
FM:
Tuning Range:
TX-7920
60 watts per channel, min. RMS, at 8 ohms, both
channels driven, from 40Hz to 20kHz, with no more
than 0.2% THD.
2 X 100 watts at 4 ohms
2 X 75 watts at 8 ohms
2 X 80 watts at 4 ohms, 1kHz (DIN)
2 X 65 watts at 8 ohms, 1kHz (DIN)
0.2% at rated power
0.1% at 30 watt output
0.2% at rated power
0.1% at 30 watt output
50 at 8 ohms
20 — 30,000 Hz + 1dB
20 — 20,000 Hz + 0.8dB
Phono: 2.5mV 750 kohms
CD/Tape Play: 150mV_//50 kohms
Tape Rec: 150mV//3.5 kohms
120mV RMS at 1kHz, 0.2% TDH
Phono: 80dB (at 5mV input, IHF-A)
CD /Tape: 100dB (1HF-A)
Bass: + 10dB at 100Hz
Treble: + 10dB at 10kHz
— ©
+7dB at 70Hz, +5dB at 10kHz
87.50—108.00MHz (50kHz steps)
TX-7900
45 watts per channel, min. RMS, at 8 ohms, both’
channels driven, from 40kHz to 20kHz, with no more
than 0.3% THD.
2 X 80 watts at 4 ohms
2 X 60 watts at 8 ohms
2 X 60 watts at 4 ohmsm, 1kHz (DIN)
2 X 50 watts at 8 ohms, 1kHz (DIN)
0.3% at rated power
0.1% at 30 watt output
0.3% at rated power
0.1% at 30 watt output
50 at 8 ohms
20 — 30,000 Hz + 1dB
20 — 20,000 Hz +0.8dB
Phono: 2.5mV 7/50 kohms
CD/Tape Play: 150mV/50 kohms
Tape Rec: 150mV//3.5 kohms
120mV RMS at 1kHz, 0.3% THD
Phono: 80dB (at 5mV input, |HF-A)
CD/Tape: 100dB (IHF-A)
Bass: + 10dB at 100Hz
Treble: + 10dB at 10kHz
+7dB at 70Hz, +5dB at 10kHz
Mono: 12.4dBf, 1.2“V, 750hmd.
1.2”V (S/N26dB, 40kHz Devi.)
750hms DIN
Stereo: 19.2dBf, 25"V, 750hms
25“ (S/N 46dB, Devi.)
750hms DIN
Mono: 18.2dBf, 2.2“V, 750hms
Stereo: 38.2dBf, 22“V, 75ohms
Usabls Sensitivity:
50dB Quieting Sensitivity:
Caputure Ratio: 1.5dB
Image Rejection Ratio: 85dB
IF Rejection Ratio: 90dB
Signal-to-Noise Ratio: Mono: 70dB
Sterep: 65dB Stereo: 65dB
Selectivity: 50dB DIN (+300kHz, 40kHz dev.)
AM suppression Ratio: 50dB
Harmonic Distortion: Mono: 0.15%
Stereo: 0.30%
30—15,000H2+1.5dB
40dB at 1kHz
30dB at 100—10,000Hz
17.2dBf, 44¢V
Frequency Response:
Stereo Separation:
Muting Level:
AM:
Tuning Range: 522—1610kHz (9kHz steps)
522—1610kHz (9kHz steps) or
530—1710kHz (10kHz steps) (World wide model)
Usable Sensitivity: 30nV
image Rejection Ratio: 40dB
{IF Rejection Ratio: 40dB
Signal-to-Noise Ratio: 40dB
Harmonic Distortion: 0.8%
GENERAL TX-7920 TX-7900
Dimensions (WXHXD): 455 120X316mm 455X120X316mm
17-15/16" X4-6/8" 12-716" 17-15/16" X4-6,8" X12-7//16"
Weight: 8.0kg, 17.6 Ibs. 7.2kg, 15.9 lbs.

1p Cracleeyap racy Ae)
Remote control transmitter RC-223S (Only Model TX-7920)
Transmitter: Infrared
Signal range: Approx. 5 meters (16ft. X 4” )
Power supply: Two “AA” batteries(1.5V X 2)
Specifications and features are subject to change without notice.
SERVICE PROCEDURES
1.Replacing the fuses 4.Memroy preservation
For continued protection against fire hazard,replace This unit does not require memory preservation batteries.
only with same type and same rating fuse. A built-in memory power back-up system preserves contents
Circuit No. Part No. Description Model of the memory during power failures and even when the
: 7 unit is unplugged. The unit must be plugged in and the
Foz pa ese Eee SCE power switch turned on and off once im order to charge the
F902 252075 2.5A-SE-EAK, Primary TX-7920 back-up system. Note that since this is not a permanent
F951 252074 2A-SE-EAK,AC outlet TX-7920 memory,the power switch must be turned on and off a few
times each month to keep the back-up system operative.
2.Safety-check out The period of time during which memory contents are
After correcting the original service problem,perform preserved after power has last been turned off varies
the following safety check before releasing the set to depending on climate and placement of the unit.
the customer. On the average, memory contents are protected over a
Connect the insulating-resistance tester between the period of 3 to 4 weeks (a minimum of 2 weeks) after
plug of power suuply cord and nickel screw on the back the last time power has been turned off. This period is
panel. shorter when the unit is exposed to very high humidity or
Specifications: More than 10M 0 used in an area with an extremely humid climate.
3.Changing the band step
A BAND STEP selector switch is not provided.
R707 85

TX-7920
EXPLODED VIEW
MODEL TX-7920

PARTS LIST
REF.NO. PARTNO. DESCRIPTION REFNO. PART NO. DESCRIPTION
1 27110680Y Front bracket <B> 87 2832A1T1Y Knob SP B <B>
27110681Y Front bracket <S> 28324173Y Knob SP B <S>
4 28133254Y¥ Back plate 91 27300833 WS-2NS,Clamp
5 27100228Y Chassis F902 252075 A\ 2.5A-SE-EAK Fuse
6 27160293Y Radiator F951 252074 A 2A-SE-EAK,Fuse
7 27141441Y Bracket LH P901 253164Y or A AS-CEE,
8 27141442Y Bracket RH 253175Y Power supply cord
9 27141443Y Bracket PC Q503,Q504 2202282, 2SA1265N-R,
12 27130643AY Bracket,shield 2202283, 2SA1265N-0,
13 27121535-2Y Back panel 2201693, 2SA1491-0,
14 27300750 A Bushing 2201694 or 2SA1491-Y or
16 27190524 KGLS-14R,Holder 2201696 2SA1491-P,Power amplifier transistor
17 27190266 KGLS-12R,Holder Q505,Q506 2202292, 2SC3182N-R,
21 834430088 3TTS+8B(BC),Self-tapping screw 2202293, 2SC3182N-0,
22 831130088 3TTW+8B,Self-tapping screw 2201703, 2S8C3855-O,
23 830440089 4TTC+8C(BC),Self-tapping screw 2201704 or 2SC3855-Y or
24 833430080 3TTP+8P(BC),Self-tapping screw 2201706 2SC3855-P,Power amplifier transistor
25 82143006 3P+6FN(BC),Pan head screw T901 2300754Y A NPT-1129P,Power transformer
26 801433 3SMS10W.SW+14B(BC),Sems Ul 1A331525-1A NARF-4325-1A,Tuner circuit pe board
| self-tapping screw ass'y
oa 31 28184471AY Top cover U2 1A331526-1A NADIS-4326-1A,Display circuit pe
| 32 834430088 3TTS+8B(BC),Self-tapping screw board ass'y
33 28140680 0.5 X 180 X8,Cushion U3 1A331527-1A NAAF-4327-1A,Power amplifier circuit
34 27270212 Spacer <P/W/Q> pe board ass’y
51 1A333701K Front panel ass'y <B> U4 1A331528-1A NASW-4328-1A,Headphone terminal
1A334701K Front panel ass'y <S> pe board ass'y
52 28125226BY End cap L US 1A331529-1 NASW-4329-1,Power switch pc board
53 28125227BY End cap R ass'y
58 28191617Y Clear plate U6 1A331530-1 NAETC-4330-1,Terminal pe board ass'y
59 833430080 3TTP+8P(BC),Self-tapping screw U7 1A331531-1A NAPS-4331-1A,Power supply circuit
60 28135199 Badge pe board ass'y
61 27175254 Leg U9 1A331533-1 NAETC-4333-1,AC outlet pe board
62 834430088 3TTS+8B(BC),Self-tapping screw ass'y
71 25060044 Terminal GND U10 1A331534-1A NAAF-4334-1A,Tone control circuit
81 28324162Y Knob LOUD <B> pe board ass'y
28324177Y Knob LOUD <S> Uli 1A331535-1 NAETC-4335-1, Volume control pe NOTE: <B>:Black model only
82 28324150-1Y Knob LEV <B> board ass'y <S>:Silver model only
28324151 Knob LEV <S> U12 1A331537-1 NAETC-4337-1,Terminal pe board ass'y
83 28324163 Knob VOL <B>
aadcke Ener SS : THE COMPONENTS IDENTIFIED BY MARK A
& saeco Sega ARE CRITICAL FOR RISK OF FIRE AND
28324184 Knob POW <S> ELECTRIC SHOCK. REPLACE ONLY WITH
86 28324170Y Knob SP A <B> PART NUMBER SPECIFIED.
28324172Y Knob SP A <S>
4
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TX-7900
EXPLODED VIEW
MODEL TX-7900

PARTS LIST
REF.NO.
1
12
13
14
16
17
21
22
23
25
26
31
32
33
34
31
52
33
38
59
61
62
71
81
82
83
85
PART NO.
27110680Y
27110681Y
28133255Y
27100228Y
27160290Y or
27160272AY
27141441Y
27141442Y
27130643AY
27121536-2Y
27300750
27190524
27190266
834430088
831130088
830440089
833430080
82143006
801433
28184471AY
834430088
28140680
27270212
1A337701K
1A338701K
28125226BY
28125227BY
28191617Y
833430080
28135199
27175254
834430088
25060044
28324162Y
28324177Y
28324150-1Y
28324151
28324181
28324182
28324140
28324184
DESCRIPTION
Front bracket <B>
Front bracket <S>
Back plate
Chassis
Radiator
Bracket LH
Bracket RH
Bracket,shield
Back panel
A Bushing
KGLS-14R,Holder
KGLS-12R,Holder
3TTS+8B(BC),Self-tapping screw
3TTW+8B,Self-tapping screw
4TTC+8C(BC),Self-tapping screw
3TTP+8P(BC),Self-tapping screw
3P+6FN(BC),Pan head screw
3SMS10W.SW+14B(BC),Sems
self-tapping screw
Top cover
3TTS+8B(BC),Self-tapping screw
0.5 X 180 X8,Cushion
Spacer
Front panel ass'y <B>
Front panel ass'y <S>
End cap L
End capR
Clear plate
3TTP+8P(BC),Self-tapping screw
Badge
Leg
3TTS+8B(BC),Self-tapping screw
Terminal GND
Knob LOUD <B>
Knob LOUD <S>
Knob LEV <B>
Knob LEV <S>
Knob VOL <B>
Knob VOL <S>
Knob POW <B>
Knob POW <S>
REF.NO.
86
87
91
F902
P901
Q503,Q504
Q505,Q506
T901
Ul
U2
U3
U4
U6
UT
U10
U12
PART NO.
28324170Y
28324172Y
28324171
28324173Y
27300833
252074
253164Y or
253175Y
2202492,
2202493,
2202243,
2202244 or
2202246
2202502,
2202503,
2202253,
2202254 or
2202256
2300758Y
1A335525-2A
1A335526-2A
1A335527-2A
1A335528-2A
1A335530-2
1A335531-2A
1A335536-1A
1A335537-2
DESCRIPTION
Knob SP A <B>
Knob SP A <S>
Knob SP B <B>
Knob SP B <S>
WS-2NS,Clamp
ZA 2A-SE-EAK, Fuse
A AS-CEE,
Power supply cord
2SA1264N-R,
2SA1264N-O,
2SA1694-O,
2SA1694-Y or
2SA1694-P,Power amplifier transistor
2SC3181N-R,
2SC3181N-O,
2SC4467-0,
2S8C4467-Y or
2SC4467-P,Power amplifier transistor
A NPT-1130P,Power transformer
NARF-4325-2A, Tuner circuit pc board
ass'y
NADIS-4326-2A,Display circuit pe
board ass'y
NAAF-4327-2A,Power amplifier circuit
pe board ass'y
NASW-4328-2A,Headphone terminal
pe board ass'y
NAETC-4330-2,Terminal pc board ass'y
NAPS-4331-2A,Power supply circuit
pe board ass'y
NAAF-4336-1A,Tone control circuit
pe board ass'y
NAETC-4337-2,Terminal pc board ass'y
NOTE: <B>:Black model only
<S>:Silver model only
NOTE: THE COMPONENTS IDENTIFIED BY MARK A.
ARE CRITICAL FOR RISK OF FIRE AND
ELECTRIC SHOCK. REPLACE ONLY WITH
PART NUMBER SPECIFIED.
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TX-7900/TX-7920
IC BLOCK DIAGRAM AND DESCRIPTION
LM7001(PLL synthesizer and controller)
Phase Detector
Charge Pump
. Divider =]
- | Shift Register Latch aoe Latch
31
CE te athe
~10—
Pin No. | Terminal Description
1 XOUT
Connect to the 7.2 MHz crystal oscillator.
3 CE Chip enable terminal. Connect to the PLL terminal of micro processor.
4 CL Serial clock input terminal. Connect to the CLOCK terminal of micro processor.
5 DATA | Serial data input terminal. Connect to the DATA terminal of micro processor.
6 SYN Not used.
é [ 7 AUTO/MONO| Auto/Mono control output terminal. “H” when Auto.
8
BO2
FM
control
signal
output
terminal.
““L”
when
FM.
1
L 9 | BO3 | AM control signal output terminal. ““L” when AM.
10 AMIN AM local oscillator input terminal.
11
FMIN
|
FM
local
oscillator
terminal.
7
L 12 Vop 1 | Power supply terminal for back-up.
13 Vopp2 Power supply terminal.
14
PD1
Charge
pump
output
of
the
phase
detector
which
constitutes
the
PLL.
High
level
is
output
when
sl
divided
local
oscillator
frequency
is
high
than the
reference
frequency.
15
PD2
In
the
opposite
case,
low
level
is
output.
Floating
occurs
when
the
frequencies
matched.
The
output
is
applied
to
the
variable
capacitor
diode
in
the
local
oscillator
through
the
low
pass
| filters.
16 Vss Ground terminal.