Pioneer 2005 Pioneer Home Audio Seminar VSX49TX

2005 Pioneer Home Audio Seminar

VSX49TX

Pioneer Electronic Service, Inc. 2005

Introduction

Why the VSX49TX?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…Display & System MicroAmplifier and Protection circuit.Power Supply DSP circuitryTrouble Shooting Tips

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

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!

Topics we will cover

Minor disassemblyDSP circuitryAmplifier & Protection circuitsSystem MicroprocessorDisplay MicroprocessorPower SupplyAdditional resources

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?

ESD precautions are a fact of life!Why do your work over and over again due to 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.

Remove only the screws necessary as shown below.

Why spend more time than you have to?

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

Keep track of the screw types.

Correct place for screw with integral flat and attachedstar washer.

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

DSP boards removed

Digital Signal ProcessingThe DSP circuit consists of 3 boards

1. AWK7719 DSP ASSY2. AWK7727 DSP3 ASSY3. AWK7725 DAC10 ASSY

DSP assemblies

DAC10 ASSY#3

DSP3 ASSY #2

DSP ASSY#1

DSP ASSY

DSP3 ASSY

DAC10 ASSY

SetupDVD Digital Input either Coaxial or OpticalSpeaker 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 illuminatefor all channels driven.

No illumination, no audio!

For your reference only

Depending on the accuracy of your scope, this voltage, 5 volts (TTL level), may vary by + or - .5 volts.

DSP Audio Block Diagram

DSP Audio Circuit

DSP Audio Circuit…continued

DSP Audio Circuit…continued

DSP Audio Circuit…continued

DSP Audio Circuit…continued

DSP Audio Circuit…continued

Test point DIR & DIT Pin 3

IC112 DIR & DITPin 3 In

Test point DIR&DIT IC101 Pin 3

More noise than signal

IC101Pin 3 DIR & DIT In

Test point DIR&DIT Pin 25

IC101Pin 25 DIR&DIT Out

Test point DIR&DIT Pin 25

IC101Pin 25 DIR&DIT Out

Test point Selector IC112 Pin 3

IC 112Pin 3 Selector In

Test point IC112 Pin 3

IC112Pin 3 Selector In

Test point Selector IC112 Pin 4

IC112Pin 4 Out

Test point Selector IC112 Pin 4

Test PointPin 4 Out

Test point DSP1 IC301 Pin 6

IC301DSP1Pin 6 In

Test point DSP1 IC301 Pin 6

Waveform very small. More noise than signal!

Test point DSP1 IC301 Pin 12

IC301DSP1Pin 12 Out

Test point DSP1 IC301 Pin 12

Test point DSP2 IC401 Pin 11

IC401DSP2Pin 11 In

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 outputfrom the unit, but you can scope the digital waveform none the less!

DSP2 IC is under here.

Test point DSP2 IC401Pin 11 In

DSP2 IC401 Pin 5 Out

IC401DSP2Pin 5 Out

DSP2 IC401 Pin 5 Out

DSP3 IC501 Pin 6 In

IC501DSP3Pin 6 In

DSP3 IC501 Pin 6 In

DSP3 IC501 Pin 12 Out

IC501DSP3Pin 12 Out

DSP3 IC501 Pin 12 Out

DAC10 CN6002 Pin 11 In

DAC10 ASSYCN6002 Pin 11 In

DAC10 CN6004 Pin 10 Out

DAC10 ASSYCN6004 Pin 10 Out

DAC10 CN6004 Pin 10 Out

End of the line! Analog audio!Success!

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.

DSP Audio Flow PathIdeal 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) CN402(DSP ASSY)

CN501(DSP3 ASSY) IC501(DSP3)(DSP3 ASSY)

CN501(DSP3ASSY) CN402(DSP ASSY)

CN402(DSP ASSY) CN707(DSP ASSY) Continued

Continued DSP PathCN6002(DAC10) IC6061(DAC10) IC6303(DAC10)

IC6305(DAC10) CN6004(DAC10)

CN5813(MotherASSY) CN5818(Mother ASSY)

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

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.

DSP troubleshooting tips

Complete loss of audioStep 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!

Easy tips for troubleshooting audioLoss of Analog audioInsert 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 channelUse capacitor, or just short(if there is no DC voltage present) Test Point to ground at any point to silencethe 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!

Amplifier and

Protection Circuit

Protection Circuit

ProblemUnit shuts off…

Display reads “AMP ERROR”

Probable cause…Damaged amplifier components.

Can there be other causes?

YES!How do I know if the amplifier is damaged for certain?

How to check for DC Offset

DC Detection, Pin 15. Should be low(0V + - .5V)in normal operation. A high(5V + - .5V) denotes DC Offset and probable Amplifier damage.

CN5819

What if DC Offset is detected?

How do I know which of the 7.1 channel(s) is bad?

Test points to narrow choices for DC Offset

Please note: DC Offset at these Test points can only be measured whenthe Power Supply voltages are up to spec.

What if the voltage is within spec?

Check these transistors for all channels. Possibly shorted!

None of those other parts bad?

Last place to look!

Amplifier

Amplifier Failures

Bad Voltage Amp IC.

If after replacing damagedIC(s), the amplifier(s) still shows DC Offset, one or both of these resistor(s) may be open!

1. Voltage Amp

Amplifier Failures

1. Amplifier output

Number 1 causeAlways replace in pairs.Don’t assume this is the only damage!

Amplifier Failures

If amplifier continues to have DC Offset after replacing output F.E.T.s, be sure to check these .1 Ohm resisters

2. Amplifier output

System Microprocessor Basics

Standby Voltage On/Off

RYCTRL= Relay ControlDon’t become confused! This output line controls the operation of the standby 5.6 V line, not the ACrelays.

Energizing AC RelaysIf no DC Offset is present, Pins 58 and 60 will change state to control Port Expander IC.

PIN 60 EXPOE2Change of state enables Expander IC 1103 to allow data input.

PIN 58 EXPDT2Data output to Expander IC1103 to control AC1 and AC2 lines for AC relays.

Turn on signal for AC relays from Micro

RAC1 & RAC2To turn on AC RelaysTip…Look for change of state

Data and control lines

Mute…Main and Multi-Room

Pin 67 changes state to mute audio lines supplying MULTI-ROOMOutputs.

Pin 66 changes state to mute all audio lines to MAIN amplifiers.

Display MicroprocessorBasics

Turn on procedure

Key Scanin lines.

Most importantfor Turn On, Key Scan 1.Look for lowwhen pressingthe Stand By button. This point, whenstatically measured,(when pushed)14.9K Ohms to ground.

IC3001

Key Scan 1 line

Communication between Micros

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

Volume up and downVolume up

Look for change of state from high to low when turning volume up.

Tip: Erratic voltage at Test point?Change Volume Encoder.

Volume down

Look for change of statefrom high to low when turningvolume down.

Tip: Erratic voltage at Test point?Change Volume Encoder.

Changing inputs

Look for change of state fromhigh to low when turning the inputknob to the left.

Tip: Changing inputs by itself?

1. Look into bulletin SI-H04018-G.PDF2. Change Input Encoder.

Changing inputs

Look for change of state fromhigh to low when turning the input knob to the right.

Tip: Changing inputs by itself?

1. Look at bulletin SI-H04018-G.PDF2. Change Input Encoder.

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 fusibleresistors! There are published Tips related to nothing but blown fuses!

To aid in TroubleshootingFirst be sure the unit is not drawing more than 1.65 amps at 120 volts!

Placing a shortacross C1002 will allow the unit to be run up slowlyon a Variac.

Normal ConditionUnit at idle, no input, no load

(Note: 2.5 amp scale) 1.65 amp + or – 10%

Note to current draw…

Normal current draw aftersettling, 1.65 amps.

Note: The unit will draw in excess of 7.5 amps as you run upthe 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!

Be sure to check all regulated supplies

Power supply voltages

CN40041. +5 volts Digital2. -5 volts Digital3. +5.6 volts 4. -5.6 volts5. +5.6 volts6. +15 volts Tuner7. +20 volts8. -20 volts

Power supply voltages

J40011. +52. Ground

Power supply voltages

J40041. +27 volts2. Ground3. -27 volts4. +55 volts5. Ground6. -55 volts

Power supply voltagesVery important!

Stand by 5.6 volts for the microprocessor

Please check on our Web Site for all Tips and Bulletins when repairing any product.

One brief note on ESDLocated on our PioneerElectronics.comwebsite under training…5S ESD TrainingThe importance of ESD safe practice and preparation is vital to our mutualsuccess. It’s no longer business asusual in the Digital Environment. Precautions must be taken or damageWILL occur…

Additional resources for ESD information…

1. ESDsystems.com

2. Desco.com

We sincerely hope you will benefit from this information.

Thank you