CRT (ITC008) Troubleshooting Guide

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SAFETY INFORMATION CAUTION

Safety information is contained in the appropriate Service Data. All product safety requirements must be complied with prior to returning the instrument to the consumer. Servicers who defeat safety features or fail to perform safety checks may be liable for any resulting damages and may expose themselves and others to possible injury.

All integrated circuits, all surface mounted devices, and many other semiconductors are electrostatically sensitive and therefore require special handling techniques.

Trademark(s)®_{Registered Marca(s) Registrada(s)}

RCA and the RCA logos are trademarks of THOMSON S.A. used under license to

TTE Corporation

Prepared by

Thomson, Inc for TTE Technology, Inc. Technical Training Department, INH905 PO Box 1976

Indianapolis, Indiana 46206 U.S.A.

FOREWORD

This troubleshooting guide is designed to aid the service technician in troubleshooting the ITC008 chassis. It will provide general information on circuit operation, troubleshooting procedures, and some common failures reported to Thomson’s Tech-Line.

The troubleshooting procedures may include circuit verification procedures used to eliminate a circuit area from the troubleshooting steps. When using the circuit verification procedures, care must be exercised to prevent further damage to the set. Reference material referred to by this manual includes:

• ESI service data

• Training Manual

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One definition of troubleshooting is the diagnosis and repair of malfunctions in electronic equipment using “Logical Analysis” and “Systematic Checks”. The key phrases of this definition are Logical Analysis and Systematic Checks. Without the application of these two principles, troubleshooting complex electronic circuitry is, at best, a hit or miss proposition. It’s also known in some circles as “Shot-Gunning”.

It’s important to remember that troubleshooting is something of an art form and is as much a mental process as it is checking waveforms and voltages. In order to effectively troubleshoot electronic equipment there are several skills the technician must have.

The technician must have:

• A solid understanding of basic electronics. He or she must understand how a transistor, resistor, capacitor, coil, diode, etc. work. They must also understand AC and DC circuits. Even with the best test equipment, without this basic understanding of electronics, the technician is only guessing as to the cause of a malfunction.

• A basic knowledge and understanding of how all the parts of the instrument function together and how they affect each other. This

overview of system operation is necessary in order to understand how the individual circuits can affect the overall operation of the equipment. This is necessary in order to be able to associate a malfunction or symptom with a circuit. In other words, could the suspected circuit cause the specific type of symptom seen?

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When discussing troubleshooting techniques or principles there are a couple of things that should be kept in mind. First, no one can teach a technician the best way to troubleshoot. Troubleshooting is a skill that’s very individualistic. This means that each and every technician will troubleshoot the same problem or malfunction differently. That doesn’t mean one method is right and the other is wrong, just that there are many different ways of solving a problem and that’s what troubleshooting is all about….Problem Solving. However, there are some basic steps and guidelines that can help a technician get started. A skilled technician will develop his or her own style with time and experience.

In most cases troubleshooting can be divided to three basic levels or steps:

1. SECTIONALIZE 2. LOCALIZE 3. ISOLATE

SECTIONALIZE; determine which major functional group or section of the instrument contains the fault. Generally, most problems can be sectionalized by carefully analyzing the symptom.

LOCALIZE; determine which major circuit within a section can or cannot cause the exhibited symptom. This usually requires checking major or key test points.

ISOLATION; find and repair the stage and/or component that has failed. This step requires detailed measurement and monitoring of signals and voltages within the suspected circuit area.

To quickly and efficiently diagnose a malfunction, the technician should follow a set sequence of steps each time he services a piece of equipment. There are five (5) basic steps in troubleshooting or symptom analysis.

1. Physical Inspection 2. Operational Check 3. Sectionalize

4. Localize 5. Isolate

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Following these five simple steps and having a basic understanding of electronics along with how the equipment works will organize the technician’s troubleshooting into a logical pattern or sequence and increase their effectiveness as a troubleshooter. Remember, these are only principles and can be interpreted in many different ways. Also, troubleshooting is a very unique skill and is learned by doing. All these principles and concepts can be applied to servicing virtually any type of product or equipment. The five steps of troubleshooting may seem obvious to some or complex to others but with time and experience they will become second nature

ITC008 Shutdown

Shutdown consists of:

• An XRP circuit that monitors the heater pulse from pin 12 of LL05.

• Over voltage and over current shutdown for pincushion

• +12Vr shutdown

• I2C Bus Communication shutdown

Determining which shutdown circuit to troubleshoot is the key. There is no quick way and from past experience, one just needs to start the process of elimination and eliminate them one at a time.

Each shutdown has it’s own “trigger”. This “trigger” is what causes the shutdown to occur. More then one “trigger” my feed into a single shutdown circuit. These types of shutdowns seem to be the most difficult to troubleshoot. For example, in the ITC008 pincushion shutdown over current and over voltage are on the same line feeding the shutdown of horizontal drive. In this same shutdown circuit, feedback from the IHVT (LL005) is used to kill drive signal while energy is still being transferred from LL005. In this shutdown there are three signals that can kill horizontal drive and shutdown the set. Knowing how to disable each will aid in troubleshooting what “trigger” is causing the shutdown.

This section will provide troubleshooting tips on how each shutdown “trigger” can be isolated in a safe manner. In some cases there is no way to isolate the trigger therefore, some understanding of the shutdown will help logic out the “trigger”. Other times it is trial and error.

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XRP EHT Shutdown

Use extreme caution when doing this procedure!!

Start by disconnecting the CRT anode lead and CRT socket. Then locate JL905 at grid location 8,UU on the main CBA. Unsolder one end. This disables both the EHT and excessive current shutdown for high voltage. Use caution with XRP EHT shutdown disabled and keep on-times to a minimum.

Over Voltage / Over Current Shutdown (Pincushion)

This is by far the easiest to disable. The feed back information that causes shutdown comes through connector BF001. By unplugging this connector the shutdown is disabled.

+12Vr Shutdown

This is not a typical shutdown circuit but more a lack of run voltage issue. The +12Vr is used as the run voltage for Horizontal driver amp TL033. If this voltage is missing TL033 will start but never run. Supplying the +12Vr from an external DC source verifies the +12Vr as the problem. This voltage should be supplied to the Cathode of DL012 and referenced to cold ground while the set is pulsing or trying to start.

I2C Bus Communication Shutdown

With this shutdown it is a trial and error situation. Error codes are logged for communication shutdown but can only be read if the set is operational. Knowing that the Tuner, MAV CBA, and Alert Guard CBA are the only communication problems reported it is safe to use the process of elimination for this shutdown.

The Alert Guard CBA is the only one that is of Plug and Play nature. Both the Tuner and MAV CBA will cause shutdown if connected or not. Therefore; trying the Tuner and the MAV are by trial and error.

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Shutdown Troubleshooting Flow Chart

The above flow chart is used to troubleshoot a dead set or shutdown condition. This chart and the troubleshooting sections found in this guide cover those scenarios found during calls to Tech-line. They do not cover all possible scenarios, only the most common or unique ones.

Apply AC power and press the power switch.

Does the set Pulse 3 times and quit or Cycle every 5 sec.

continuously

Pulse at 5 Sec Intervals

Cycles 3 Times

Disconnect the Alert Guard Module.

Try to turn on the set. Does the set

start?

Suspect the Alert Guard Module Disconnect the

Pincushion Connector BF001

Try to turn on the set. Does the set

start? Troubleshoot Horizontal Deflection Troubleshoot Power Supply Troubleshoot System Control Communication I2C Bus Tuner and MAV?

Suspect the Pincushion Module

Try to turn on the set. Dead or Pulsing? Dead Pulsing YES NO YES NO Does the set have

Alert Guard? NO

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ITC008 Power Supply Troubleshooting

(Dead Set, Power supply voltages missing or incorrect)

NOTE: DP027 will short whenever feedback is lost or an excessive load on the

secondary of LP003 is present. This will shut down the power supply. IF DP027 is shorted, check FZP61. If FZP61 is open, check the +13.1V for excessive load and check the feedback circuit (IP001, TP022, and IP050) for proper operation.

1. Check RAW B+, if not OK check the full wave bridge rectifier DP002/003/004/005 and it’s associated components.

2. If RAW B+ OK, check the current sensing resistor RP020. If open, this would indicate there has been a severe over current condition between the drain and source of TP020. Check and replace all defective active components on the primary side of LP003. Check for excessive loads off secondary of LL03 before reapplying AC power.

3. Check for DC voltage and waveform on the gate of TP020. A waveform, like the one on page 11, indicates the oscillator is running. If there is no waveform unsolder the drain of TP020 and check for 7.8Vdc on the gate. 7.8Vdc on the gate of TP020 indicates start-up circuit is working go to step 5. If a waveform is present on the Gate of TP020, the primary switching of the supply is working.

3 2 9 5 RAW B+ 1 2 3 4 1 2 3 +13.1V Ω 0.27 G D S 1 +6.3Vs +21.5V +126V +19.5V Pwr Good TP193,192 PG1 11 10 12 13 14 15 16 18 IP001 DP030 RP155 IP050 CP040 RP041 RP026 RP040 DP040 RP030 RP006 RP007 DP005 DP002 DP004 DP003 FP001 CP008 TP020 DP033 RP021 RP033 RP031 RP029 RP023 RP027 TP025 RP132 TP023 TP022 RP028 RP125 DP023 RP020 DP025,026 LP003 DP080 CP080 FZP60 3.15A FZP93 500mA FZP61 3.15A RP066 DP093 CP094 CP064 DP063 DP097 RP056 RP054 RP158 Slow Start RP037,038 DP037 CP037,038 CP039 CP022 TP052 DP057 RP057 RP151 Burst Mode IV001 pin 63 CP062 DP202 CP206 DP061 CP024,025 DP027 RP052 Beam Current Sense 8.2V 27V 15V 9.1V 27V

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Start-up Circuit Test:

Working unit voltages with the Drain of TP020 open: (HOT GND Reference)

• Gate = 7.8V

• Startup ckt = 8.9V (Measured on TP025 (E))

• TP025 C = 8.0V, E = 8.9V, B = 8.3V

• Junction of RP006 and 007 = 32.4V

4. If DC on gate of TP020 is wrong, check TP025, DP027, DP023, RP006, and RP007 and replace if suspect. Hint: 27V on the emitter of TP025 indicates that the base circuit of TP025 is open. Check DP023, RP125, RP132, or open circuit to pin 3 of LP003. If there is 0V on the emitter of TP025 and DP027 is shorted, check the regulation feedback circuit associated with IP001 and IP050.

5. If no waveform on gate of TP020 (DC OK), check TP022, TP023 and their associated components. Replace all transistors if one has failed or is suspect. If TP020 has failed more than likely the other transistors have been stressed and the circuit will self-destruct again when plugged into 120 AC.

Gate of TP020 Waveform Stby Mode

Device Resistance to Cold GND DP080 45.7K DP061 1.4M DP093 5K DP063 7K

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Dual Voltage Regulator IP030

There are two output voltages from IP030 but only one is switched. Pin 4 controls the output on pin 8 (7.9V). When pin 4 goes high, there should be 7.9V on pin 8. This is easy to check by simply removing (unsoldering) pin 4 and checking the output. If voltage is present on pins 1 and 2 then pin 8 should be 7.9V if IP030 is working correctly.

The other output on pin 9 is 3.3V. This voltage is used for System Control standby B+ and Pin 6 of IP030 is the reset voltage for IV001 (SysCon). When power is first applied, IV001 turns on the dual regulator (IP030) for a short period of time. During this time Degauss is energized and pin 8 of IP030 is switched on supplying the 7.9V. No relay click could indicate IP030 3.3V problem.

IP030 Troubleshooting

1. Check for 13.1V on pin 1 and 2 of IP030. If the voltage is correct go to step 2. If missing or not correct troubleshoot standby power supply.

2. Unsolder pin 4 of IP030 and check for 7.9V on pin 8. If the voltage is present, go to step 3. If the voltage is low or missing suspect IP030.

3. Reconnect pin 4 and check for 3.3V on pins 6 and 9. If present, go to step 4. If the voltage is low or missing suspect IP030.

4 IP030 Dual Reg. 8 9 6 Reset +7.9Vs +3.3Vs 1 2 ₃ IP31 1 2 +5Vs 1 IV001 LL05

33 Horiz Out _Drive/OutHoriz Pwr ON 14 +181Vr +33Vr +12Vr -12Vr DH01 33V 63 Power Supply Control IP01,IP50 +13.1Vs Burst

Hi = Burst & DAM Mode Lo = Energy Mode TP52 RP57 DP57 RP153 RP151 9.1V DP36 CP66 RP166 FZP66 +VCC +7.9Vs CRT Vertical Tuner 60 54 56 TR02 Reset Switch

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4. With pin 4 of IP030 connected, monitor pin 8 and press the power switch. If 7.8V momintarly comes up, system control and regulator are working correctly, suspect a Horizontal startup problem. If there is no change on pin 8 troubleshoot system control.

ITC008 Deflection Troubleshooting

In order to troubleshoot deflection we must first understand where the signals are generated. In the ITC008, IV001 (TV Processor) is used to generate both the Vertical and Horizontal drive signals. The generation of these drive signals depends on several external circuits and proper operation of IV001.

First, being system control, IV001needs to have VCC (Stby), GND, OSC, and RESET to function. Next, some sort of user interface (Remote or FPA) to tell IV001 what to do. IV001 also needs a set of instructions to perform the expected command. This instruction is in the form of “DATA” found in the EEPROM (IR001). The “DATA” is used to set up registers in IV001. These registers include Horizontal timing, Vertical timing, and shutdown settings. Transfer of "DATA" happens each time the set is turned on. Failure to properly transfer the "DATA" will result in a dead set condition.

This troubleshooting section assumes certain sections of IV001 are working correctly. These sections are System Control and Signal Processing.

IV001 TV Micro Clk/Data 2,3 5,6 IR001 EEPROM 6 7 64 KB/LED IR BR001 to Front Panel 8 +5Vs 14 +7.9VsD 61 +3.3V VDD RESET 60 +3.3V VCCD Core 54,56 1 PWR ON 39 12,18,30,41,57 GND 58,59 QV001 58 59 57 OSC GND IN OUT 33 36 Horiz Out XRP EHT PLL Ckts 15, 19, 16, 17 21, 22 VDrive

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Vertical Deflection Troubleshooting

(No Vertical Deflection)

Setup: Remove CRT Socket, apply AC power and turn on set. When troubleshooting

a Vertical deflection problem where the set is operated without deflection it is customary to remove the CRT socket(s) to prevent the CRT from being burnt.

1. Check for –12V on pin 4 of IF001 referenced to cold ground. If missing suspect DL010 and RL010 or a problem with the –12V supply. If correct proceed to step 2.

2. Check for proper waveform on pins 1 and 7 of IF001. These waveforms are generated by IV001. If not correct, troubleshoot IV001 vertical section or suspect EEPROM alignment data corruption. If waveforms are present, check for 48V P-P on pin 5 of IF001. If present IF001 is working and problem is in the yoke circuit. If not go to the next step.

3. Compare the voltage found on pin 2 with that found on pin 6 of IF001. These two voltages should be about .3V different. If they are equal, DF010 should be replaced.

4. Check for –10.3V on pin 3 of IF001. This is the boost circuit for IF001. When this voltage is missing suspect IF001, CF010 and DF010. If correct IF001 is working and problem is in the yoke circuit.

Hint: If set is shutting down and removing DL062 allows the set to operate with out

vertical deflection, suspect IF001, DF010, and CF010. These are the most common failures of the Vertical circuit causing the set to shutdown. Also check the +12Vr circuit (RL012 and DL012) off pin 6 of IHVT (LL005).

NOTE: Settings in the EEPROM (Vertical) can also cause shutdown. Misalignment

of Vertical Slope (parameter #06) and Vertical Amplitude (parameter #08) can cause the protection signal from the E/W module to activate and shutdown the instrument.

To correct for this problem, temporarily disconnect BL101on the E/W module to restart the instrument and reset both parameters.

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IV001 21 22 14 PWR AMP IF001 Vertical Output 5 1 7 4 2 6 3 RV06 RF02 DF02 RV05 DF03 RF03 RF04 RF06 CF05 DF10 CF10 DF101 DF102 RF101 CF101 DF01 56V RF08 _RF09 CF09 RF07 CF08 BF002 RF102

Beam Current Limit +7.9Vs -12Vr +12Vr -12Vr BF001 to Pincushion Vcc VDriveA VDriveB

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Horizontal Deflection Troubleshooting

(No Horizontal Drive)

1. Unsolder collector of TL35 (Horizontal Output Transistor).

2. Monitor the base of TL35 and press the power switch. The set will cycle until power is pushed again. A horizontal drive pulse should be present at the base of TL35 while it is cycling.

3. If a drive pulse is present on the base of TL35, IV001 and the driver circuit are working correctly. The problem is off the collector of TL35. Suspect Yoke, Yoke return circuit, pincushion, LL05 and the secondary side of LL05.

4. If the drive pulse is missing check for drive at pin 33 of IV001. If missing, suspect CV004, CV005, CV006, CV007, CV008, and RV001 components off of pins 15,16,17, and 19 of IV001. Corrupt data in the EEPROM could also prevent horizontal drive.

5. If drive pulses are present at pin 33 of IV001, check for them at the emitter of TL031. If they are missing, disconnect DL062 and recheck. Drive pulses on the emitter of TL031 with DL062 removed indicates that drive shutdown has occurred (See shutdown troubleshooting section). If drive is present at the emitter of TL031 with DL062 in circuit, check for drive at pin 3 of LL032 (LL033 alt). If drive is present at pin 3 of LL032, suspect LL032 (LL033 alt) or a connection problem with LL032 (LL033 alt). If missing go to next step.

6. Check for 13.0V at the collector of TL033 in standby mode. If missing, suspect RL037 and RL038 or TL033 (shorted). If present suspect DL035, RL034 or the +12Vr source.

NOTE: Pin 33 of IV001 (Horizontal Drive) will have 7.0Vdc when drive is missing. Possible causes of no Horizontal Drive:

• Corrupt EEPROM data

• +VCC missing at pins 14 and 39 of IV001

• Internal OSC off frequency. Capacitors on pins 15, 19, 16, and 17 of IV001 effect PLL circuits.

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Anode Focus Screen IHVT LL05 5 8 Heater & XRP Htr Return 13 12 11 10 1 9 IV001 33 Hout CL30 TL31 TL060/061 TL62 TL33 LL32 TL35 CL21 DL21 CL23,25,26 RL25,26 DL25 LL26 BL005 +126V RL34 DL35 RL37 RL38 CL35 RL41 to 44 +181Vr +33Vr 33V -12Vr +12Vr Horiz Yoke +12Vr 6 7 XRP +13.1Vr Pin 12 LL05 1 3 6 4 RL07 RL63 RL68 DL62 DL30 RL36 +7.9VsA RV73 Vcc 14 +7.6VsD 36 EHT Pin 8 LL05 Beam Current Sense to PWR IP050-3 TL50 Buffer RL12 DL12 CL13 RL10 DL10 CL11 LL40 DL01 CL41 RL40 DL40 TZ01 DZ01,03,05 +7.6VsE 34 BF001 to Pincushion CBA RL06 RF07 from 3 2 1 1 2 3 BL003 from Pincushion CBA Feed Back

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Alternate Vertical Troubleshooting Information

Repeat failure of the vertical output IC (IF001) can be difficult to find and expensive. The following information pertains to troubleshooting the vertical circuit with the vertical yoke disconnected. By unloading the vertical circuit it is possible to make checks to the vertical output IC with out damaging it.

1. Disconnect the CRT socket and BF002 vertical yoke connector.

2. Using the Voltage chart, check for correct DC on all pins of IF001. If a voltage is not correct see the notes section of the Voltage chart for possible causes.

Pin No. Voltage Notes

1 +.7

Incorrect waveform from IV001 or missing wavefrom. Check for open or shorted components between pin 21 of IV001 and pin 1 of IF001. Check feedback resistor RF006.

2 +12.2

Check for open circuit from +12Vr source. Remember if the +12Vr is missing the set will shutdown.

3 -13

This voltage is internally generated by IF001 and pin 4. If missing, suspect IF001 or pin 4 voltage missing. Common parts for incorrect voltage are: IF001, DF010, CF010.

4 -13

Check DL010 and RL010 off pin 7 of LL005. If RL010 is open check for shorts on the -12Vr source.

5 +1.6

This voltage is controlled by IF001 and the input pins 1 and 7. If pins 1 and 7 are correct suspect IF001, RF006, RF009, and RF007. Voltage High indicates no drive to pins 1 and 7 of IF001.

6 +11.8

This voltage should be lower then pin 2. DF010 is a common failure along with IF001.

7 +.7

Incorrect waveform from IV001 or missing wavefrom. Check for open or shorted components between pin 22 of IV001 and pin 7 of IF001.

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ITC008 Pincushion Shutdown Troubleshooting

Pincushion shutdown occurs when TL101 (Pin Driver) pulls excessive current through RL111. As the current increases so does the voltage. IL101 pin 12 monitors this voltage change and when the voltage exceeds the reference voltage found on pin 13 of IL101, IL101 (comparator) switches states and puts a high on pin 14. This high is sensed by TL061 base turning it on and killing horizontal drive. To defeat this shutdown circuit and troubleshoot the pincushion circuit, disconnect DL062.

Some of the common failures in the pincushion circuit have been:

• DL101

• DL102

• DL012

1. Verify the set is in pincushion shutdown by disconnecting BF001. If the set stays on, the pin circuit is causing the shutdown. If the set still shuts down the problem is not with the pincushion circuit.

2. Unsolder DL062 cathode. This removes the shutdown protection. Use caution when operating the set with DL062 disconnected. Short on-time is recommended. 1 7 8 14 12 13 3 2 9 10 6 IL101 5 1 2 3 1 2 3 BL101 RL150 RL134 PL143 RL131 RL132 RL107 RL106 PL140 RL108 DL138 RL138 CL138 RL144 LL122 CL144 RL145 TL101 CL122 DL121 DL122 BL103 DL119 CL123 47V RL112 RL111 DL118 RL118 DL117 RL117 RL141 PL141 RL104 RL105 RL136 RL137 to CL021 and DL021 RL110 CL110 DL113 CL114

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3. Monitor TL101 (Pin Driver) pin 3 for +18Vdc and 9.5Vp-p waveform and turn on the set. If the voltage is missing or incorrect, suspect he Pincushion Circuit Board Assembly (CBA). If the voltage is high suspect an input signal problem or incorrect adjustment.

Note: This voltage can reach +130Vdc. Caution should be taken if this

voltage exceeds +50V. +50V is the over voltage shutdown of the pin circuit. With DL062 disconnected the over voltage shutdown is also disabled. Running the set with voltage in excess of +50V can cause additional damage. Short on time is highly recommended.

Tech-Tip: The Pincushion CBA is a replaceable module, however; troubleshooting

the module to component level can be accomplished. One of the common failures has been cold solder connections on BL101. An oscilloscope and multimeter are required to isolate other problems. Keep in mind that the voltage readings found in the schematic may not be exactly what your set has. The pincushion circuit has adjustments for the different screen sizes therefore the voltages and waveforms can be slightly different. For example: TL101 pin 3 shows to be 18.0V, our test set used to develop this troubleshooting guide measured 20.8V. An acceptiable range for the voltage on pin 3 of TL101 would be from +15V to +30V.

1 7 8 14 12 13 3 2 9 10 6 IL101 5 1 2 3 1 2 3 BL101 RL150 RL134 PL143 RL131 RL132 RL107 RL106 PL140 RL108 DL138 RL138 CL138 RL144 LL122 CL144 RL145 TL101 CL122 DL121 DL122 BL103 DL119 CL123 47V RL113 RL112 RL111 DL118 RL118 DL117 RL117 RL141 PL141 +12.2Vpin RL104 RL105 RL136 RL133 RL134 RL137 to CL021 and DL021 RL110 CL110 DL114 DL113 RL114 CL114 +12.2Vpin

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CRT (ITC008) Troubleshooting Guide

SAFETY INFORMATION CAUTION

FOREWORD

Contents

FOREWORD ... 3

SAFETY INFORMATION CAUTION ... 3

Troubleshooting Fundamentals ... 5

ITC008 Shutdown... 7

XRP EHT Shutdown ... 8

Over Voltage / Over Current Shutdown (Pincushion)... 8

+12Vr Shutdown ... 8

I2C Bus Communication Shutdown ... 8

Shutdown Troubleshooting Flow Chart ... 9

ITC008 Power Supply Troubleshooting ... 10

Dual Voltage Regulator IP030 ... 12

IT008 Deflection Troubleshooting ... 13

Vertical Deflection Troubleshooting ... 14

Horizontal Defleciton Troubleshooting ... 16

Alternate Vertical Troubleshooting Information ... 18