Technical Bulletin
T763
Date:
Note:
Previous T.B.’s required: Revised from T763-H2005-05
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DESCRIPTION: You may have the complaint that the subwoofer or other channels are
popping when switching inputs or when turning on and off.
REASON: The channel that is popping may have a muting transistor damaged due to an
external source or subwoofer causing static damage to the transistor.
SOLUTION: Replace the transistor and install a 4700 pF capacitor between the base and
collector on the pre amp pc board , as shown in the following two schematics. The use of a
surface mount capacitor is recommended. Placing the capacitor on the bottom of the board
between the base and collector of each muting transistor is preferred . See figure 2 on page 2.
Note: It is recommended to install this capacitor to each channel’s muting transistor. The
following are the designations of the muting transistors,
Q608,Q609,Q610,Q611,Q612,Q613,Q615,Q617 and Multi source muting transistors
Q632,Q633.
Figure 1
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2005-05R
March 7/05 Subject: Static protection for
muting transistors
Implemented in production from serial number:R49T76305615
YES
NO
muting circuit
Subwoofer/Multi
muting circuit
All other channels
Page 1 of 2
board
Figure 2
Technical Bulletin
T763
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2005-05R
4700pF surface
mount capacitor
between base
and collector
pins of muting
transistor on the
pre amp pc
Contact:
NAD Electronics International
633 Granite Court
Pickering, ON Canada L1K 3K1
Voice: 905-831-0799 FAX 905-837-6357
www.nadelectronics.com
Page 2 of 2
Technical Bulletin T763
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2004-01
Date: June 15
Note:
Previous T.B.’s required:
T
T
DESCRIPTION: At high volume setting with no signal on an un-terminated analogue input,
there maybe some audible residual hum noise and whistling sound coming from one or more
channels.
REASON: The residual noise is coming from power supply ground and DSP board ground.
The whistle noise is coming from the DSP board.
SOLUTION: Remove the DSP board and order a replacement DSP board from our spares
department .Order under the number in the service manual. Perform the following ground
changes to lower residual hum noise.
T763 Ground changes
Change the cable between J617 on Pre-out board and Multi-channel RCA from AWG22 to
1.
AWG18.
Implemented in production from Serial number: R44T76303751
YES
NO
, 2004 Subject: Residual Noise
Figure 1
Note: If this is not present on the unit, add AWG18 cable between Pre-out RCA and Multichannel RCA.
Page 1 of 4
Technical Bulletin T763
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2004-01
T763 Ground Changes
2. For J705B on AUDIO PCB, cut all the AGND pin. That is pin 1, 3, 9 & 12. Please refer
to figure 2.
Figure 2
3. Install a 18AWG ground wire from the DSP board to the Multi channel RCA connector ground. See Figure 3.
Figure 3
Page 2 of 4
Technical Bulletin T763
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2004-01
T763 DSP Changes
4. When installing new DSP board please perform the following. Float the DSP AGND
(including the grounding bracket) from chassis using an insulated washer. See figure 4 and
figure 5.
FIGURE 4
Contact:
NAD Electronics International
633 Granite Court
Pickering, ON Canada L1K 3K1
Voice: 905-831-0799 FAX 905-837-6357
www.nadelectronics.com
Page 3 of 4
Technical Bulletin T763
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2004-01
T763 DSP Changes
5. Mount the front panel ground cable to the nearest front panel screw. See figure 5.
Figure 5
Contact:
NAD Electronics International
633 Granite Court
Pickering, ON Canada L1K 3K1
Voice: 905-831-0799 FAX 905-837-6357
www.nadelectronics.com
Page 4 of 4
Technical Bulletin
T763
Product: A/V Receivers
Hardware Technical Bulletin: T763-H2004-02
Date: June 15
Note:
Previous T.B.’s required:
T
T
DESCRIPTION: The unit may be experiencing intermittent audio or display. The unit may
not always power up.
REASON: The flat ribbon cables, primarily the ones running from the front panel but may
include all flat ribbon cables. They may have intermittent contact due to oxidization.
SOLUTION: Clean all ribbon connectors using an eraser or preferably a non alcohol based
cleaner which will leave no residue. See figures 1, 2 and 3.
NO
, 2004 Subject: Flat Ribbon Cables
YES
Figure 1
Locate and remove the
ribbon cables, front
panel cables shown.
Page 1 of 2
Technical Bulletin
T763
Product: A/V Receivers
Hardware Technical Bulletin: T763-H2004-02
Ribbon cables are easily
unplugged from these
Figure 2
Figure 3
Contact:
NAD Electronics International
633 Granite Court
Pickering, ON Canada L1K 3K1
Voice: 905-831-0799 FAX 905-837-6357
www.nadelectronics.com
Clean the ends of the
ribbon cables with
eraser or non alcohol
based cleaners.
Page 2 of 2
Technical Bulletin T763
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2004-03
Date:
Note:
Previous T.B.’s required:
DESCRIPTION: To improve the compatibility of HDTV signals with some TV/Monitors.
REASON: When decoding HDTV signals some TV/Monitors may experience horizontal
sync loss.
SOLUTION: Perform the following change to the Component video board.
On the component video PCB U4301
June 1, 2004 Subject: HDTV Component
Video change
Implemented in production from Serial number: R44 series and onwards
T
T
YES
NO
A) Link the following pins on U4301;
Pins 9 to 10
Pins 12 to 13
Pins 14 to 15
Figure1
Page 1 OF 2
Technical Bulletin T763
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2004-03
HDTV Component Video Change
B) Remove C4317, C4319, C4321.
Figure 2
C) Replace C4316, C4318, and C4320 with 1000 uF 6V.
Figure 3
Contact:
NAD Electronics International
633 Granite Court
Pickering, ON Canada L1K 3K1
Voice: 905-831-0799 FAX 905-837-6357
www.nadelectronics.com
Page 2 OF 2
Technical Bulletin
T763
Date:
Note:
Previous T.B.’s required:
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DESCRIPTION: Unit may shut down, shortly after turn on.
REASON: There is a diode on the standby board that maybe operating intermittantly.
SOLUTION: Locate and identify D756 on the standby board. Change only if the diode is a
1N4148. Change from a 1N4148 to a 1N4004 or equivalent. See figure 1 for details.
Figure 1
Product: A/V Receiver
Hardware Technical Bulletin: T763-H2005-04
February 28/05
Implemented in production from serial number:R44T76304065
YES
NO
Subject:
Intermittantly shuts down
D756
CHANGE
FROM
1N4148 TO
1N4004
Contact:
NAD Electronics International
633 Granite Court
Pickering, ON Canada L1K 3K1
Voice: 905-831-0799 FAX 905-837-6357
www.nadelectronics.com
Page 1 of 1
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