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2005 Pioneer Home Audio Seminar
VSX-49TX
1
Pioneer Electronic Service, Inc. 2005
Welcome one and all!
Your instructor…Dave Kraus
2
Introduction

Why the VSX49TX?
–

The VSX49TX is not current product, however it
tends to be the most difficult to repair!
What will be covered?
–
1.
2.
3.
4.
5.
The receiver in general; more specifically…
DSP circuitry
Display & System Micro
Amplifier and Protection circuit.
Power Supply
Trouble Shooting Tips
3
This seminar will be specifically
about troubleshooting techniques,
no operation instructions,
no theory!
4
What will you get out of this?


You will learn the most successful
troubleshooting methods designed to get the
unit on and off your bench as quickly as
possible.
You will learn more accurate repair techniques
and avoid having to replace costly boards on
out-of-warranty units. Replacing expensive
boards can sometimes mean the difference
between getting the repair or having the
customer walk!
5
Bright Idea
In an effort to keep you awake, we will
break for minimum of 10 minutes every
other hour of training!
6
Topics we will cover
Minor disassembly
 DSP circuitry
 Amplifier & Protection circuits
 System Microprocessor
 Display Microprocessor
 Power Supply
 Additional resources

7
Disassembly
• Remove no more than you have to!
• Use caution when removing the back
panel screws. They are different !
You are using your ESD wrist strap aren’t you?
Sorry folks. ESD precautions are a fact of life!
Why do your work over and over again due to
8
static damaged components!
To start…
1. Place unit as pictured and remove top, bottom and side covers.
2. Prop up unit as pictured for easy access.
3. Remove all screws holding the DSP boards, as well as any
attached connectors or wire ties.
9
Remove only the screws necessary as shown below.
Why spend more time than you have to?
10
Use caution when removing screws.
There are 3 different types !
11
Keep track of the screw types.
Correct place for screw with
integral flat and attached
star washer.
12
With the screws removed, gently pull back on the back
panel, while extracting the DSP and DSP3 assemblies.
13
DSP boards removed
14
Digital Signal Processing
The DSP circuit consists of 3 boards
1. AWK7719 DSP ASSY
2. AWK7727 DSP3 ASSY
3. AWK7725 DAC10 ASSY
15
DSP assemblies
DAC10 ASSY
#3
DSP3 ASSY
#2
DSP ASSY
16
#1
DSP ASSY
17
DSP3 ASSY
18
DAC10 ASSY
19
Setup
DVD Digital Input either Coaxial or Optical
 Speaker setup 5.1 or 5 channel(without
Subwoofer)
 Must use DVD with Surround information
{Be sure to look at front panel display}
 For the purpose of this seminar, we will
follow the left surround channel only.

Indicators must illuminate
for all channels driven.
No illumination, no audio!
20
For your reference only
Depending on the accuracy of your scope, this voltage,
5 volts (TTL level), may vary by + or - .5 volts.
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DSP Audio Block Diagram
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DSP Audio Circuit
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DSP Audio Circuit…continued
24
DSP Audio Circuit…continued
25
DSP Audio Circuit…continued
26
DSP Audio Circuit…continued
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DSP Audio Circuit…continued
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Test point DIR & DIT Pin 3
IC112 DIR & DIT
Pin 3 In
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Test point DIR&DIT IC101 Pin 3
More noise than signal
IC101
Pin 3 DIR & DIT In
30
Test point DIR&DIT Pin 25
IC101
Pin 25 DIR&DIT Out
31
Test point DIR&DIT Pin 25
IC101
Pin 25 DIR&DIT Out
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Test point Selector IC112 Pin 3
IC 112
Pin 3 Selector In
33
Test point IC112 Pin 3
IC112
Pin 3 Selector In
34
Test point Selector IC112 Pin 4
IC112
Pin 4 Out
35
Test point Selector IC112 Pin 4
Test Point
Pin 4 Out
36
Test point DSP1 IC301 Pin 6
IC301
DSP1
Pin 6 In
37
Test point DSP1 IC301 Pin 6
Waveform vary small. More noise than signal!
38
Test point DSP1 IC301 Pin 12
IC301
DSP1
Pin 12 Out
39
Test point DSP1 IC301 Pin 12
40
Test point DSP2 IC401 Pin 11
IC401
DSP2
Pin 11 In
41
Question…
How do I troubleshoot the DSP2 IC?
It’s located directly under the DSP3 ASSY.
Answer..
Simply remove the DSP3 ASSY.
There won’t be any sound output
from the unit, but you can scope the
digital waveform none the less!
DSP2 IC is under here.
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Test point DSP2 IC401Pin 11 In
43
DSP2 IC401 Pin 5 Out
IC401
DSP2
Pin 5 Out
44
DSP2 IC401 Pin 5 Out
45
DSP3 IC501 Pin 6 In
IC501
DSP3
Pin 6 In
46
DSP3 IC501 Pin 6 In
47
DSP3 IC501 Pin 12 Out
IC501
DSP3
Pin 12 Out
48
DSP3 IC501 Pin 12 Out
49
DAC10 CN6002 Pin 11 In
DAC10 ASSY
CN6002 Pin 11 In
50
DAC10 CN6004 Pin 10 Out
DAC10 ASSY
CN6004 Pin 10 Out
51
DAC10 CN6004 Pin 10 Out
End of the line! Analog audio!
Success!
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Conclusion to DSP troubleshooting
1. Follow the digital signal into and out of
DSP1, DSP2 and DSP3 ICs. Compare to
waveforms seen in this presentation.
2. Look at the digital signal entering DAC10
ASSY. Look for analog signal to follow.
3. Loss of signal at any point requires back
tracking to last good test point.
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DSP Audio Flow Path
Ideal path to follow(Left Surround)
JA107(DSP ASSY)
IC101(DSP ASSY)
IC112(DSP ASY)
IC301(DSP1)(DSP ASSY)
IC410(Selector)(DSP ASSY)
IC401(DSP2)(DSP ASSY)
CN707(DSP ASSY)
CN6002(DAC10)
IC6303(DAC10)
IC6061(DAC10)
IC6305(DAC10)
CN5813(Mother ASSY)
IC6301(DAC10)
CN6004(DAC10)
CN5818(Mother ASSY)
Continued
54
Continued DSP Path
CN5001(VR &Pre Out)
IC5001(VR & Pre Out)
IC5061(VR & Pre Out)
CN5006(VR & Pre Out)
CN4801(Power Amp)
IC4401(Power Amp)
JA4801(Power Amp)
Speaker
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DSP socket issues
IC304 on DSP ASSY and IC504 on DSP3 ASSY
Cold solder connections on these sockets can cause loss
of audio in DSP mode. For complete loss of audio, at
times associated with these sockets, try resoldering
socket to PCB first. At the same time, clean and coat
pins of socket and IC with DeOxit, or similar
compound. If this doesn’t resolve the problem, remove
the IC socket and solder the IC directly to the board.
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DSP troubleshooting tips
Complete loss of audio
Step 1. Use Multi-Channel input jacks at rear.
Step 2. Switch unit to Multi-Channel.
Step 3. If audio returns, unit has a DSP ASSY problem. If still no
audio, remove DSP ASSY board and repeat steps 1 and 2.
If audio returns, probable cause…DSP ASSY.
Step 4. If unit still has no audio, probable cause is VR & PRE OUT
ASSY and beyond.
Step 5.
To further isolate the problem, remove Main in/ Preout
jumpers and insert audio directly into Main in, front
channel. If still no audio, unit has amplifier problem.
Don’t forget to reinsert jumpers!57
Easy tips for troubleshooting audio
Loss of Analog audio
Insert audio(Signal Injector), or noise(put finger on
Test Point to generate noise), to ensure continuation
of signal past that point. Move forward or backward
in the circuit as needed.
Noise on Analog audio channel
Use capacitor, or just short(if there is no DC voltage
present) Test Point to ground at any point to silence
the noise. From that point and beyond, the circuit is
OK. Move forward or backwards in the circuit as
needed.
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Please use caution and exercise good judgment!
DSP questions?
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Amplifier
and
Protection Circuit
60
Protection Circuit
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Problem
Unit shuts off…
Display reads “AMP ERROR”
Probable cause…Damaged amplifier
components.
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Can there be other causes?
YES!
How do I know if the amplifier
is damaged for certain?
63
How to check for DC Offset
CN5819
DC Detection, Pin 15. Should be
low(0V + - .5V)in normal operation. A
high(5V + - .5V) denotes DC Offset
and probable Amplifier damage.64
What if DC Offset is detected?
How do I know which of
the 7.1 channel(s) is bad?
65
Test points to narrow choices for
DC Offset
Please note: DC Offset at these Test points can only be measured when
the Power Supply voltages are up to spec.
66
What if the voltage is within spec?
Check these transistors for all channels.
Possibly shorted!
67
None of those other parts bad?
Last place to look!
68
Protection Circuit
questions?
69
Amplifier
70
Amplifier Failures
1. Voltage Amp
Bad Voltage Amp IC.
If after replacing damaged
IC(s), the amplifier(s) still
shows DC Offset, one or
both of these resistor(s)
may be open!
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Amplifier Failures
1. Amplifier output
Number 1 cause
Always replace in
pairs.
Don’t assume this is
the only damage!
72
Amplifier Failures
2. Amplifier output
If amplifier continues to
have DC Offset after
replacing output F.E.T.s,
be sure to check these .1
Ohm resisters
73
Amplifier questions?
74
System Microprocessor
Basics
75
Standby Voltage On/Off
RYCTRL= Relay Control
Don’t become confused! This
output line controls the operation
of the standby 5.6 V line, not the AC
relays.
76
Energizing AC Relays
If no DC Offset is present, Pins 58 and 60 will change state to control Port
Expander IC.
PIN 60 EXPOE2
Change of state enables
Expander IC 1103 to allow
data input.
PIN 58 EXPDT2
Data output to Expander
IC1103 to control AC1 and
AC2 lines for AC relays.
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Turn on signal for AC relays from Micro
RAC1 & RAC2
To turn on AC Relays
Tip…Look for change of state
Data and control lines
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Mute…Main and Multi-Room
Pin 67 changes state to mute
audio lines supplying MULTI-ROOM
Outputs.
Pin 66 changes state to mute all
audio lines to MAIN amplifiers.
79
System Micro
questions?
80
Display Microprocessor
Basics
81
Turn on procedure
Key Scan 1 line
Key Scan
in lines.
Most important
for Turn On,
Key Scan 1.
Look for low
when pressing
the Stand By button.
This point, when
statically measured,
(when pushed)
14.9K Ohms to ground.
IC3001
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Communication between Micros
Wake-Up output signal from IC3001, Pin 7, to input IC 5801,
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pin 20.
Volume up and down
Volume up
Look for change of state
from high to low when
turning volume up.
Tip: Erratic voltage at Test point?
Change Volume Encoder.
84
Volume down
Look for change of state
from high to low when turning
volume down.
Tip: Erratic voltage at Test point?
Change Volume Encoder.
85
Changing inputs
Look for change of state from
high to low when turning the input
knob to the left.
Tip: Changing inputs by itself?
1. Look into bulletin SI-H04018-G.PDF
2. Change Input Encoder.
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Changing inputs
Look for change of state from
high to low when turning the input
knob to the right.
Tip: Changing inputs by itself?
1. Look at bulletin SI-H04018-G.PDF
2. Change Input Encoder.
87
Display Micro
questions?
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Things to keep
in mind
First and foremost, don’t overlook
the obvious!
This is a very complex receiver.
There are 16 fuses, A.K.A. IC Protectors,
11 regulator ICs and countless fusible
resistors! There are published Tips
related to nothing but blown fuses!
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To aid in Troubleshooting
First be sure the unit is not drawing more than 1.65 amps at 120 volts!
Placing a short
across C1002 will
allow the unit to be
run up slowly
on a Variac.
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Normal Condition
Unit at idle, no input, no load
(Note: 2.5 amp scale)
1.65 amp + or – 10%
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Note to current draw…
Normal current draw after
settling, 1.65 amps.
Note: The unit will draw in excess of 7.5 amps as you run up
the AC voltage. Look for the current to drop as soon as you stop
increasing the voltage. If it doesn’t, pull the plug! The unit is shorted!
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Be sure to check all regulated supplies
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Power supply voltages
CN4004
1.
2.
3.
4.
5.
6.
7.
8.
+5 volts Digital
-5 volts Digital
+5.6 volts
-5.6 volts
+5.6 volts
+15 volts Tuner
+20 volts
-20 volts
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Power supply voltages
J4001
1.
2.
+5
Ground
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Power supply voltages
J4004
1.
2.
1.
4.
5.
6.
+27 volts
Ground
-27 volts
+55 volts
Ground
-55 volts
96
Power supply voltages
Very important!
Stand by 5.6 volts for the microprocessor
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Power Supply
questions?
98
Service issues, Repair Tips
Symptom: No audio
Cure: Check for missing
5V line. Check IC4023 in
Power Supply.
Models Covered:
VSX47TX, VSX49TX,
VSX49TXI
Tip Date: August 14 2004
99
Symptom: UNIT SHUTS DOWN INTERMITTANTLY.
MAY NOT REACH 0dB REFERRENCE AUDIO
LEVEL.
Cure: MANY HIGH END, LOW IMPEADANCE
SPEAKERS (Less than 6 ohms), CAN CAUSE UNIT
TO GO INTO PROTECT MODE UNDER CERTAIN
CIRCUMSTANCES. INSTALL SI BULLETIN: SIH03061-G
Models Covered: VSX47TX, VSX49TX
Tip Date: March 25 2004
This Tip involves the installation of replacement
ICs and resistors on the Mother board.
100
Symptom: CAN NOT FIND IC504 ON DSP
ASSY. AS PER SI-H03061-G. WHAT TO DO?
Cure: IC504 IS ACTUALLY ON DSP3 ASSY.
Models Covered: VSX49TX
Tip Date: March 25 2004
101
Symptom: Channel out in Surround or
Surround Back channel.
Cure: Check appropriate DAC for
channel, IC6402, IC6401, IC6302 and
IC6301 on DAC10 PCB (AWK7725).
Models Covered: VSX49TX
Tip Date: February 07 2004
102
Symptom: Random digital noise(no audio)
coming from speaker out.
Cure: Missing +5V line to I/O PCB. Open
IC4023(fuse) on Local Supply Assy.
(AWX7887). IC4024(fuse) on -5V line will also
cause the same problem.
Models Covered: VSX47TX, VSX49TX
Tip Date: February 07 2004
103
Symptom: Pop and static sound from
Surround Right output.
Cure: Tracked back to DAC, IC6302. Note:
This same Pop and Static noise can be
generated from any of the other channels,
caused by the following ICs IC6301, IC6201,
IC6202, IC6301, IC6302, IC6401, and IC6402
located on the DAC10 PCB (AWK7725).
Models Covered: VSX49TX
Tip Date: February 05 2004
104
Symptom: Once powered up, the shuts off
and continues to cycle on and off.
Cure: Found missing 5.6V "v" line (CN4004,
pin 3) due to open IC4035 (ICP 1.25A,
AEK7010) on the "Local Supply Assy"
(AWX7887) board. Replaced and restored
normal operation.
Models Covered: VSX47, VSX47TX, VSX49,
VSX49TX
Tip Date: November 04 2003
105
Symptom: No Right channel. All other
functions are fine.
Cure: Found loose mounting nut on Input
Select control. Tightened same. Right
channel audio was restored.
Models Covered: VSX49TX
Tip Date: August 25 2003
106
Symptom: No DSP audio
Cure: cold solder IC504 pins
46/47/48 on DSP3 board
Models Covered: VSX49TX
Tip Date: May 19 2003
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Bulletin: SCH04004
Models Covered: VSX49TX, VSX49TXI, VSAAX10AIS, VSAAX10IS,
VSXAX10, VSXAX10IG
June 01 2004
Subject: See SI Bulletin This Tip involves correction to Service Manual.
Reason: See SI Bulletin
SCH04004.pdf
File Size: KB Bulletin: SI-H03090B-G
Models Covered: VSX49TX, VSX47TX, VSX49TXI, VSAAX10, VSXAX10,
VSXAX10IS, VSXAX10IG
February 20 2004
Subject: Main volume level unexpectedly turns up/down.
Reason: Depending on the position of the rotary encoder, neutral voltage
(approx. 2.5 volts) appears at output of the encoder. The Display Micro in
the unit may become confused.
SI-H03090B-G.pdf
File Size: KB Bulletin: SI-H04051
Models Covered: VSX49TX, VSAAX10, VSXAX10, VSX49TXI, VSAAX10IS,
VSXAX10IG
December 11 2003
Subject: Change the capacitors in VR & PRE OUT ASSY(AWX7888) and
DAC10 ASSY (AWK7225).
Reason: To improve the sound quality. This Tip involves changing
108
SI-H04051.pdf
Capacitor values.
Bulletin: SI-H04049
Models Covered: VSX49TX, VSX47TX, VSAAX10, VSXAX10, VSX49TXI,
VSAAX10IS, VSXAX10IG, VSX59TXI
December 05 2003
Subject: Change resistor (R2351) in S-VIDEO Assy.
Reason: To improve the performance of Video circuit.
SI-H04049.pdf
File Size: KB Bulletin: SI-H04024
Models Covered: VSX49TX, VSAAX10, VSX47TX, VSX49TXI, VSAAX10IS,
VSXAX10IG
September 16 2003
Subject: Change of parts in DSP ASSY.
Reason: Standardization of parts.
SI-H04024.pdf
File Size: KB Bulletin: SI-H04018-G
Models Covered: VSX49TX, VSX47TX, VSAAX10, VSXAX10, VSX49TXI,
VSXAX10IG, VSAAX10IS
July 01 2003
Subject: Input selector/Listening mode selector unexpectedly switches to
a different source /a different mode.
Reason: Main microcomputer may miss-detect the output voltage from
the rotary encoders.
109
SI-H04018-G.pdf File Size: KB
File Size: KB Bulletin: SI-PG02007
Models Covered: VSX49TX
July 01 2003
Subject: VSX49TX Fire Wire upgrade
Reason: No longer applicable
SI-PG02007.pdf
File Size: KB Bulletin: SI-H03088
Models Covered: VSX49TX, VSX49TXI
March 06 2003
Subject: See SI Bulletin
Reason: See SI Bulletin This Tip involves entering the Service Mode.
SI-H03088.pdf File Size: KB
Bulletin: SI-H03072
Models Covered: VSX49TX
January 20 2003
Subject: See SI Bulletin
Reason: See SI Bulletin This Tip involves correction of the DSP board
part number.
SI-H03072.pdf
110
File Size: KB Bulletin: SI-H03068
Models Covered: VSX29TX, VSAE07, VSX39TX, VSAE08, VSX49TX, VSAAX10,
VSX49TXI, VSAAX10IS, VSXAX10IG
January 20 2003
Subject: Additional information regarding the directions for removing PCB
ASSY.(Remove two resistors from PCB ASSY before installing it to the remote
unit.)Please refer to page: 3/5 - page:
Reason: Production convenience.
SI-H03068.pdf
File Size: KB Bulletin: SI-H03061-G
Models Covered: VSX49TX, VSX47TX, VSAAX10, VSXAX10
December 03 2002
Subject: When using speakers in which the actual impedance is very low and
the input signal is a very high level, power down is activated.
Reason: In some popular expensive speakers (such as some models of B&W
speakers), the actual impedance seems to be lower than the catalog spec (8
ohms or 6 ohms) This Tip involves changing ICs and resistors on the Mother
board.
SI-H03061-G.pdf File Size: KB
111
File Size: KB Bulletin: SI-H03023-G
Models Covered: VSAAX10, VSX49TX, VSX47TX, VSXAX10
May 29 2002
Subject: This problem occurs only with these conditions; sound with a
digital connection (such as DVD) stops for a moment when a source
unit is being connected Reason: When the source unit is turned on/off,
the optical signal from the source unit stops for a moment along with
this incident PLL will be locked off in the DIR-IC.
SI-H03023-G.pdf
File Size: KB Bulletin: SI-H03012
Models Covered: VSX49TX
May 02 2002
Subject: Addition of Capacitors to V-CONVERT Assy
Reason: To prevent the oscillation of the Video Amp.
SI-H03012.pdf
112
File Size: KB Bulletin: SI-H02081-G
Models Covered: VSX49TX, VSX47TX
March 15 2002
Subject: Updated specification. Some models from
other manufacture have already adopted.
Reason: To meet with new format of Digital signal
(88.2KHz). Though the new digital format will be
affected in 2002, some models from other
manufactures have already been updated.
SI-H02081-G.pdf
File Size: KB Bulletin: SI-H02056
Models Covered: VSX49TX
November 08 2001
Subject: See SI Bulletin
Reason: See SI Bulletin
This Tip involves correction of the
SI-H02056.pdf File Size: KB
Service Manual.
113
Any other questions?
114
One brief note on ESD
Located on our PioneerElectronics.com
website under training…
5S ESD Training
The importance of ESD safe practice
and preparation is vital to our mutual
success. It’s no longer business as
usual in the Digital Environment.
Precautions must be taken or damage
WILL occur…
Why spend additional time and money on ESD blown parts!
115
Make sure you have the basics!
1. ESD Work mat
2. ESD Wrist strap
3.
Training!
116
Additional resources for
ESD information…
1.
Ecosystems.com
2.
Disco.com
117
Technical help via the Web
Datasheets!
118
DatasheetArchive.com
Freescale.com
Adobe Acrobat Files
AK4114VQ
TC74VHC257FT
AK5383VS
TC9274N-016
BU4094BC
PCM1704U-1
119
We sincerely hope you will benefit from
the information presented here today.
Thank you
for
Attending!
120