1. 2005 Pioneer Home Audio Seminar
VSX49TX
Pioneer Electronic Service, Inc. 2005

2. Welcome one and all!
Your instructor…Dave Kraus

3. Introduction Why the VSX49TX? What will be covered?
The VSX49TX is not current product, however it tends to be the most difficult to repair!
What will be covered?
The receiver in general; more specifically…
DSP circuitry
Display & System Micro
Amplifier and Protection circuit.
Power Supply
Trouble Shooting Tips

4. This seminar will be specifically about troubleshooting techniques, no operation instructions,
no theory!

5. 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!

6. Bright Idea
In an effort to keep you awake, we will break for minimum of 10 minutes every other hour of training!

7. Topics we will cover Minor disassembly DSP circuitry
Amplifier & Protection circuits
System Microprocessor
Display Microprocessor
Power Supply
Additional resources

8. 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
static damaged components!

9. 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.

10. Remove only the screws necessary as shown below.
Why spend more time than you have to?

11. Use caution when removing screws.
There are 3 different types !

12. Keep track of the screw types.
Correct place for screw with
integral flat and attached
star washer.

13. With the screws removed, gently pull back on the back panel, while extracting the DSP and DSP3 assemblies.

14. DSP boards removed

15. Digital Signal Processing
The DSP circuit consists of 3 boards
1. AWK7719 DSP ASSY
2. AWK7727 DSP3 ASSY
3. AWK7725 DAC10 ASSY

16. DSP assemblies
DAC10 ASSY #3
DSP3 ASSY #2
DSP ASSY #1

17. DSP ASSY

18. DSP3 ASSY

19. DAC10 ASSY

20. 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!

21. For your reference only Depending on the accuracy of your scope, this voltage, 5 volts (TTL level), may vary by + or - .5 volts.
Most important thing, it either is or is not there!

22. DSP Audio Block Diagram

23. DSP Audio Circuit

24. DSP Audio Circuit…continued

25. DSP Audio Circuit…continued

26. DSP Audio Circuit…continued

27. DSP Audio Circuit…continued

28. DSP Audio Circuit…continued

29. Test point DIR & DIT Pin 3
IC112 DIR & DIT
Pin 3 In

30. Test point DIR&DIT IC101 Pin 3
More noise than signal
IC101
Pin 3 DIR & DIT In

31. Test point DIR&DIT Pin 25
IC101
Pin 25 DIR&DIT Out

32. Test point DIR&DIT Pin 25
IC101
Pin 25 DIR&DIT Out

33. Test point Selector IC112 Pin 3
Pin 3 Selector In

34. Test point IC112 Pin 3
IC112
Pin 3 Selector In

35. Test point Selector IC112 Pin 4
Pin 4 Out

36. Test point Selector IC112 Pin 4
Pin 4 Out

37. Test point DSP1 IC301 Pin 6
IC301
DSP1
Pin 6 In

38. Test point DSP1 IC301 Pin 6
Waveform vary small. More noise than signal!

39. Test point DSP1 IC301 Pin 12
IC301
DSP1
Pin 12 Out

40. Test point DSP1 IC301 Pin 12

41. Test point DSP2 IC401 Pin 11
IC401
DSP2
Pin 11 In

42. Question… Answer.. 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.

43. Test point DSP2 IC401Pin 11 In

44. DSP2 IC401 Pin 5 Out
IC401
DSP2
Pin 5 Out

45. DSP2 IC401 Pin 5 Out

46. DSP3 IC501 Pin 6 In
IC501
DSP3
Pin 6 In

47. DSP3 IC501 Pin 6 In

48. DSP3 IC501 Pin 12 Out
IC501
DSP3
Pin 12 Out

49. DSP3 IC501 Pin 12 Out

50. DAC10 CN6002 Pin 11 In
DAC10 ASSY
CN6002 Pin 11 In

51. DAC10 CN6004 Pin 10 Out
DAC10 ASSY
CN6004 Pin 10 Out

52. DAC10 CN6004 Pin 10 Out
End of the line! Analog audio!
Success!

53. 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.

54. 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) IC6061(DAC10) IC6301(DAC10)
IC6303(DAC10) IC6305(DAC10) CN6004(DAC10)
CN5813(Mother ASSY) CN5818(Mother ASSY)
Continued

55. 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

56. 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.

57. Don’t forget to reinsert jumpers!
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!

58. 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.
Please use caution and exercise good judgment!

59. DSP questions?

60. Amplifier Protection Circuit
and
Protection Circuit

61. Protection Circuit

62. Problem Unit shuts off… Display reads “AMP ERROR”
Probable cause…Damaged amplifier
components.

63. Can there be other causes?
YES!
How do I know if the amplifier is damaged for certain?

64. How to check for DC Offset
CN5819
DC Detection, Pin 15. Should be low(0V V)in normal operation. A high(5V V) denotes DC Offset and probable Amplifier damage.

65. What if DC Offset is detected?
How do I know which of the 7.1 channel(s) is bad?

66. 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.

67. What if the voltage is within spec?
Check these transistors for all channels.
Possibly shorted!

68. None of those other parts bad?
Last place to look!

69. Protection Circuit questions?

70. Amplifier

71. 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!

72. Amplifier Failures Number 1 cause 1. Amplifier output
Always replace in pairs.
Don’t assume this is the only damage!

73. 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

74. Amplifier questions?

75. System Microprocessor
Basics

76. 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.

77. 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.

78. 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

79. 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.

80. System Micro
questions?

81. Display Microprocessor
Basics

82. Turn on procedure IC3001 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

83. Communication between Micros
Wake-Up output signal from IC3001, Pin 7, to input IC 5801,
pin 20.

84. 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.

85. Volume down Look for change of state from high to low when turning
Tip: Erratic voltage at Test point?
Change Volume Encoder.

86. 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.

87. 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.

88. Display Micro
questions?

89. 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!

90. 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.

91. Normal Condition Unit at idle, no input, no load 1.65 amp + or – 10%
(Note: 2.5 amp scale)

92. 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!

93. Be sure to check all regulated supplies

94. Power supply voltages CN4004 1. +5 volts Digital 2. -5 volts Digital
volts Tuner
volts
volts

95. Power supply voltages
J4001 +5
Ground

96. Power supply voltages J4004 1. +27 volts 2. Ground -27 volts

97. Power supply voltages Very important!
Stand by 5.6 volts for the microprocessor

98. Power Supply
questions?

99. 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

100. Symptom: UNIT SHUTS DOWN INTERMITTANTLY
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: SI-H03061-G Models Covered: VSX47TX, VSX49TX Tip Date: March This Tip involves the installation of replacement
ICs and resistors on the Mother board.

101. 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

102. Symptom: Channel out in Surround or Surround Back channel
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

103. Symptom: Random digital noise(no audio) coming from speaker out
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

104. Symptom: Pop and static sound from Surround Right output
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

105. 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

106. Symptom: No Right channel. All other functions are fine
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

107. Symptom: No DSP audio Cure: cold solder IC504 pins 46/47/48 on DSP3 board Models Covered: VSX49TX Tip Date: May

108. Bulletin: SCH04004 Models Covered: VSX49TX, VSX49TXI, VSAAX10AIS, VSAAX10IS, VSXAX10, VSXAX10IG June          Subject: See SI Bulletin Reason: See SI Bulletin
This Tip involves correction to Service Manual.
SCH04004.pdf 
 File Size: KB Bulletin: SI-H03090B-G Models Covered: VSX49TX, VSX47TX, VSX49TXI, VSAAX10, VSXAX10, VSXAX10IS, VSXAX10IG February          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          Subject: Change the capacitors in VR & PRE OUT ASSY(AWX7888) and DAC10 ASSY (AWK7225). Reason: To improve the sound quality.
SI-H04051.pdf  
This Tip involves changing
Capacitor values.

109. Bulletin: SI-H04049 Models Covered: VSX49TX, VSX47TX, VSAAX10, VSXAX10, VSX49TXI, VSAAX10IS, VSXAX10IG, VSX59TXI December          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          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          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. SI-H04018-G.pdf  File Size: KB

110.  File Size: KB Bulletin: SI-PG02007 Models Covered: VSX49TX July          Subject: VSX49TX Fire Wire upgrade Reason:
SI-PG02007.pdf 
 File Size: KB Bulletin: SI-H03088 Models Covered: VSX49TX, VSX49TXI March          Subject: See SI Bulletin Reason: See SI Bulletin SI-H03088.pdf  File Size: KB
Bulletin: SI-H03072 Models Covered: VSX49TX January          Subject: See SI Bulletin Reason: See SI Bulletin SI-H03072.pdf  
No longer applicable
This Tip involves entering the Service Mode.
This Tip involves correction of the DSP board
part number.

111. File Size: KB Bulletin: SI-H03068 Models Covered: VSX29TX, VSAE07, VSX39TX, VSAE08, VSX49TX, VSAAX10, VSX49TXI, VSAAX10IS, VSXAX10IG January          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          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

112. File Size: KB Bulletin: SI-H03023-G Models Covered: VSAAX10, VSX49TX, VSX47TX, VSXAX10 May          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          Subject: Addition of Capacitors to V-CONVERT Assy Reason: To prevent the oscillation of the Video Amp. SI-H03012.pdf 

113. File Size: KB Bulletin: SI-H02081-G Models Covered: VSX49TX, VSX47TX March          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          Subject: See SI Bulletin Reason: See SI Bulletin SI-H02056.pdf  File Size: KB
This Tip involves correction of the
Service Manual.

114. Any other questions?

115. One brief note on ESD 5S ESD Training
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!

116. Make sure you have the basics!
1. ESD Work mat
2. ESD Wrist strap
3. Training!

117. ESD information… Additional resources for 1. Ecosystems.com
2. Disco.com

118. Technical help via the Web
Datasheets!

119. Adobe Acrobat Files DatasheetArchive.com Freescale.com
AK4114VQ TC74VHC257FT
AK5383VS TC9274N-016
BU4094BC
PCM1704U-1

120. Thank you for Attending!
We sincerely hope you will benefit from the information presented here today.
Thank you
for
Attending!