Harman Kardon TU-940 Service Manual
The Harman Kardon
Model TU-940
AM/FM STEREO DIGITAL RDS TUNER
TU 940 RDS
Power
1 2 3 4 5
6 7 8 9 0
LOCALDX RDSPTY RT CT TA EON TUNED STEREOMONO TUNINGPRESET
RF LEVELSTANDBYWIDENARROWCLOCKTIMERONOFFSLEEPAUTOMEMORYSCAN
Auto/Man
Band
RF Mode FM Mode
IF Band
Display
Mode
Remote sensor
Memory
Display
Direct
Tune/Pst
PTY
Character
Pst Scan
Manual A
Tuning
CONTENTS
LEAKAGE TEST…………………………...…2
SPECIFICATIONS…………………………....3
CONTROL A ND FUNCTIONS………………4
BLOCK DIAGRAM……………………………7
DISASS EMBLY PROCED URES……………8
CIRCUIT DESCRIPTION…………………..13
ALIGNMENT PROCEDURES……………..16
GENERA L UNIT EXPLOD ED VI EW. .…….2 1
PRINTED CIRCUIT BOARDS…………..…22
ELECTRICAL PARTS LIST……………......24
IC FUNCT IO NAL BLOCK DIAGRAM … … ..3 2
PACKAGE……………………………………33
WIRING DIAGRAM…………………………35
SCHEMATIC DIAGRAMS… … … ..…… … ..36
harman/kardon
Parts and Service Office
80 Crossways Par k West, Woodbury, N.Y. 11797
Printed in Korea
LEAKAGE TEST
Before returning the unit to the user, perform the
following safety checks:
1. Inspect all lead dress to makes certain that leads
are not pinched or that hardware is not lodged
between the chassis and other metallic parts in the
unit.
2. Be sure that any protective devices such as
nonmetallic control knobs, insulating fishpapers,
cabinet backs, adjustment and compartment covers
or shields, isolation resistor-capacity networks
mechanical insulators, etc. Which were removed for
servicing is properly reinstalled.
3. Be sure that no shock hazard exists; check for
leakage current using Simpson Model 229 Leakage
Tester, standard equipment item no. 21641, RCA
model WT 540A or use alternate method as follows:
plug the power cord directly into a 230-volt AC
receptacle ( do not use an isolation transformer for
this test.). Using two clip leads, connects a 1500
ohm, 10-watt resistor paralleled by a 0.15 µF
capacitor, in series with all exposed metal cabinet
parts and a known earth ground such as a water
pipe or conduit. Use a VTVM or VOM with 1000
ohms per volt, or higher sensitivity to measure the
AC voltage drop across the resistor. (This test
should be performed with the power switch in both
the on and off positions.)
A reading of 0.35 volt RMS or more is excessive
and indicates a potential shock hazard which must
be corrected before returning the unit to the owner
2
SPECIFICATION
FM SECTION Nominal Limit
Test Condition: 40 kHz DEV., 1kHz Frequency.
Tuning Range/Step 87.5 MHz –108 MHz/50 kHz
Usable Sensitivity (-26dB S/N)
Mono [ 8.15 dBf [ 12.25 dBf
Limiting Sens at –3 dB [ 7.2 dBf [ 9.2 dBf
50dB Quieting Sens
Mono [ 16.2 dBf [ 19.2 dBf
Stereo [ 39.2 dBf [ 42.8 dBf
Total Harmonic Distortion
Mono [ 0.1% [ 0.25%
Stereo [ 0.15% [ 0.35%
Signal to Noise Ratio (1mV RF INPUT)
Mono 〈 80 dB 〈 75dB
Stereo 〈 75 dB 〈 70 dB
Stereo Separation at 98 MHz ( NORMAL)
1kHz 〈 50 dB 〈 40 dB
10kHz 〈 40 dB 〈 35 dB
Muting and Automatic Tereshold at 98 MHz
31.2 6 2 dBf 31.2 6 4 dBf
Auto Stop Level 31.2 6 2 dBf 31.2 6 4 dBf
Selectivity NORMAL/NARROW 6 300 kHz
〈 50/70 dB 〈 34/60 dB
Auto Scan Error 6 15 kHz 6 20 kHz
Frequency Response at 30 Hz –15 kHz
6 0.5 dB + 1/22.5 dB
Image Rejection at 106 MHz 〈 80 dB 〈 65dB
AM Suppression 〈 60 dB 〈 50 dB
RDS Sensitivity 31.2 6 2 dBf 31.2 6 4 dBf
Output Voltage
Mono 5006100mV 5006150mV
AM SECTION Nominal Limit
Test Condition: 400 Hz, 30% Modulation
Tuning Range/Step
MW 522 kHz – 1611 kHz/9 kHz
Usable Sensitivity (2 20 dB S/N)
MW: 594 kHz, 1404 kHz [ 500 mV [ 800 mV
Signal to Noise Ratio (0.1 V INPUT)
MW: 999 kHz 〈 55dB 〈 48 dB
Frequency Response at 2 6 dB
MW 160 Hz ~ 2.5 kHz 150 Hz ~ 2 kHz
Selectivity at 6 9 kHz
MW: 999 kHz 〈 35dB 〈 30 dB
A.G.C. Figure of merit at 999 kHz
〈 50 dB 〈 45 dB
Image Rejection
MW: 1404 kHz 〈 40 dB 〈 35 dB
Total Harmonic Distortion ( 0.1 V INPUT)
MW: 999 kHz [ 0.7% [ 1.2 %
Tuned Level
MW: 999 kHz 800 mV 6 3 dB 800 mV 6 5 dB
Output Voltage ( 5mV INPUT)
165 6 30 mV 165 6 40 mV
DIMENSIOS (W ⋅ H ⋅ D) 442 ⋅ 92 ⋅ 350
WEIGHT 3.9 Kg
POWER SUPPLIES AC 230 V, 5-Hz
POWER CONSUMPTION 15W
These specifications are service target specs.
Specifications and components are subject to change without notice.
Overall performance will be maintained or improved.
3
CONTROL AND FUNCTIONS
101112141315161732
Power
1
TU 940 RDS
1 2 3 4 5
6 7 8 9 0
LOCALDX RDSPTY RT CT TA EON TUNED STEREOMONO TUNINGPRESET
RF LEVELSTANDBYWIDENARROWCLOCKTIMERONOFFSLEEPAUTOMEMORYSCAN
Auto/Man
Band
RF Mode FM Mode
IF Band
Display
Mode
Remote sensor
Memory
Display
Direct
PTY
Character
Tune/Pst
4 5 6 7 8 9
Pst Scan
Tuning
1. POWER
Press to turn the unit on. The ring around the button will glow green. Press again to turn the unit
off. The ring will glow red and the word “STANDBY” will appear in the display.
2. NUMBERIC KEYS
Use to select the preset number of a station that has been entered into the preset memories or
to store a station in the memory in conjunction with MEMORY
7.
To recall a previously programmed station, press the appropriate numeric button(s). For single
digit numbers (1-9), press the number and the station will be tuned at once or in a few seconds.
To recall preset locations 10 though 30, press the desired buttons in order and the station will be
tuned at once.
To use the buttons to enter a station to the preset memory, see page 10.
3. FLUORESCENT DISPLAY
The display panel contains a large display for station frequency information and RDS data, as
well as status indicators for various tuner functions and 5-step RF level indicator bars.
4. BAND
Press to change between FM and AM frequency bands..
5. IF BAND (FM TUNING ONLY)
Press to change the passband of the intermediate frequency to compensate for interference
form adjacent station.
NARROE: When reception is disturbed by interference from other stations, press until
NARROW is lit. This improves reception.
NORMAL: For normal reception, press until NORMAL is lit.
6. DISPLAY MODE
Press to change between bright and dim display lighting or display off.
4
7. MEMORY
Use to enter station into the preset memory or to start the Auto Preset Memory function. The
memory indicator blinks when the button is pressed. See page 10 for instructions on using the
memory system.
8. TUNE/P.SET
Press to light PRESET indicator. When the indicator is lit, the TUNING knob
step through the preset stations in ascending or descending order. When the PRESET indicator
is not lit, normal tuning (auto or manual) is activated.
9. P.SET SCAN
Press to automatically step through each of the stations that has been preset into the memory.
Each programmed station will play for approximately five seconds. To stop at a desired station,
press again, while the station is playing.
10. TUNING
This knob has a number of functions, although it’s primary use is to select stations. In normal
use, turn the knob in either direction to move through the selected band to find a station. When
the TUNED indicator lights, the station is properly locked in.
A number of automated tuning methods are also available:
In the FM mode, when AUTO/MAN
tuning knob clockwise will cause the tuner to scan higher frequencies. When turned
counterclockwise, lower frequencies will be scanned. The tuner will stop at the first station that
has acceptable signal strength. Turn the knob again in the same direction to tune to the next
available station.
When TUNE/P.SET
10 will move the tuner up or down through the stations programmed into the unit’s memory. The
Tuning Knob also functions as a selector for PTY
descriptions of these functions on page 13 and below.
8 is pressed so that the PRESET indicator is lit, turning the TUNING knob
17 is pressed so that the AUTO indicator is lit, turning the
12 and Character 11 functions. See
10 can be used to
11. CHARACTER
Permits you to enter or modify the name of any station, which is not broadcasting in RDS.
To enter a name, press CHARACTER once. A line will flash under the first space in the display,
Turn the tuning knob until the desired character (letter, number or symbol) appears.
Press again to move to the next space. Repeat this procedure until the name is spelled out,
using the tuning knob to select a character and the Character button to move to the next space.
When the last character has been programmed, press MEMORY
location (1-30) using the NUMBER keys
The name may be called up at any time by pressing DISPLAY
12. PTY
Press to select a particular PTY (Program Type) according to the information transmitted by an
RDS station. After pressing PTY, turn the TUNING knob
you wish to search.
For detailed RDS information, see page 12.
2.
10 to select the program type for which
7, and then select memory
14.
5
13. DIRECT
Pressing this button will start the sequence for direct entry of a station’s frequency. After
pressing the button simply press the proper Numeric Keys
information see next page.
14. DISPLAY
Press to display current frequency, station name or RDS information. Press again to move to
the next item in the following order:
If a non-RDS-station is tuned:
Frequency, station name (if a name is entered manually). If an RDS station is tuned: Station
Name, Band and Frequency, Program Type (PTY), Radio Text, Time.
If an RDS station is tuned (only FM) indicators for available RDS information will be shown next
to the red RDS indicator in the display: PTY (Program Type), RT (Radio Text) or CT (Clock
Time) will light up, if the station is broadcasting this information. The RDS information available
will vary.
15. FM MODE
Press to change mode of FM reception.
Press so that the MONO indicator is not lit and all stations received with a signal strength high
enough for acceptable audio performance will be heard, either in stereo (the red stereo indicator
is lit) or in mono, just as they are transmitted. The sound of all weaker stations will be muted.
Press so that the MONO indicator is lit and all stations, including all stereo transmissions, will be
heard in mono.
NOTE: When experiencing weak or noisy reception of a stereo broadcast, reception quality may
be improved by pressing FM MODE to switch to mono.
2 to tune the station. For more
16. RF MODE (FM TUNING ONLY)
Press to compensate for RF intermodulation noise caused by interference from other strong
stations in your area.
In urban areas or with cable systems where reception is strong and there are many stations,
press until LOCAL indicator is lit, This will attenuate the signal strength of all stations received
( RF LEVEL indicator bars in the display will show lower signal strength) and thus may reduce
intermodulation noise and provide better sound quality.
When tuning distant stations, press so that the local indicator is not lit. This improves the tuner’s
ability to receive weak signals with lower noise, and – when needed – press the FM MODE
button
17. AUTO/MANUAL
Press so that the AUTO indicator is lit to engage the automatic tuning system. When in the
AUTO mode, turning the TUNING knob
with sufficient signal strength and stop. Turn the Tuning knob again to continue through the
frequency band to the next station.
15 until the MONO indicator is lit to make weak station audible.
10 cause the tuner to scan for the next available station
6
7
DISASSEMBLY PROCEDURES
8910
11
12
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