The subject set doesn't power up. After investigating, high voltage will come up for a few seconds, then it powers down. The front panel LED flashes with 2 short flashes. Any suggestions?
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If there is a failure in any of the scan circuits, the set will go in to protect mode. This is most probably what is happening.
Before starting to work on a TV set is is best to have the full shop service manual with the schamatics, with all the required service details about the set.
The fault can be any of the components in the associated cricuits. This can be a bad cap, open resistor, or a failed semiconductor.
In the case where a set is going in to the protect mode, it is difficult to take voltage readings, because the power supply is being partialy shut down. The parts of the supply that runs the high voltage and scan circuits are shut down, and also the uPC makes sure that the CRT is biased off to protect it.
It is most common that capacitors go out of specs with age. To properly test the caps you would need a cap an ESR meter. The other way to test caps is to replace them until you have worked out all the defective ones. This is shotgunning for a bad cap. With this method, you an end up changing a lot of caps, and they were not the fault.
In the case of the other types of components a DVM can be used to check them. IC's must be changed to properly check them. It is impossible to properly check an IC just with a DVM.
This is an idea of what troubleshooting is.
Jerry G.
Posted on Apr 21, 2008
The following lists the chain of events that occur when you turn on a printer. You can follow this list as one means of determining if the printer is operating correctly. The exact chain of events depends upon the last power down condition and where the printer has last determined the printhead is positioned, this is stored in non-volatile RAM. The Checklist is the primary reference for troubleshooting power-up problems.
1. Power cord is plugged in and the power switch is turned on:
2. Power supply senses AC line voltage conditions (110 VAC or 220 VAC)
and enables DC voltages. If an overload occurs, the printer turns off the high voltage DC supplies, causing a "blink" effect on the Control Panel LEDs.
3. BIST test flashes the PE LED very briefly at a fast rate until the end of the
next test.
4. The Boot loader performs CPU initialization and RAM test. It then sends
the boot loader version to the serial port.
5. Power-On Self Test (POST) initializes the Control Panel. The Control
Panel LED turns red, green, orange, and then off. The Control Panel LCD then goes black and then clear. The POST version displays on the LCD
and waits two seconds. During this time the operator can press the Back
button to bypass the remaining POST test.
6. Low level Power-On Self Test (POST) diagnostics are performed. The
Control Panel displays status messages as each sub-test is performed.
This test takes about 8 seconds. All LEDs are off during the test.
If POST diagnostics pass, the Control Panel displays the Xerox logo and turns on the green LED.
If the test detects an error, the error message displays on the LCD and the printer flashes the LEDs with a repeating error code pattern.
7. The VxWorks operating system is initialized and engine code is started.
This takes about 15 seconds. The Xerox logo is displayed.
8. Print Engine Self Test (PEST) diagnostics are then performed. These test
the heaters, clutches, motors and solenoids. As each clutch is tested, you hear clicking with four high tones as each motor is tested. This test takes about 30 seconds.
9. The printer now runs the mechanical initialization. The exact sequence
depends on the initial position of the printhead and wiper assembly.
The following lists the chain of events that occur when you turn on a printer.
You can follow this list as one means of determining if the printer is operating correctly. The exact chain of events depends upon the last power down condition and where the printer has last determined the printhead is positioned, this is stored in non-volatile RAM.
1. Power cord is plugged in and the power switch is turned on:
2. Power supply senses AC line voltage conditions (110 VAC or 220 VAC)
and enables DC voltages. If an overload occurs, the printer turns off the high voltage DC supplies, causing a "blink" effect on the Control Panel LEDs.
3. BIST test flashes the PE LED very briefly at a fast rate until the end of the
next test.
4. The Boot loader performs CPU initialization and RAM test. It then sends
the boot loader version to the serial port.
5. Power-On Self Test (POST) initializes the Control Panel. The Control
Panel LED turns red, green, orange, and then off. The Control Panel LCD then goes black and then clear. The POST version displays on the LCD and waits two seconds.
During this time the operator can press the Back button to bypass the remaining POST test.
6. Low level Power-On Self Test (POST) diagnostics are performed. The
Control Panel displays status messages as each sub-test is performed. This test takes about 8 seconds. All LEDs are off during the test. If POST diagnostics pass, the Control Panel displays the Xerox logo and turns on the green LED.
If the test detects an error, the error message displays on the LCD and the printer flashes the LEDs with a repeating error code pattern.
7. The VxWorks operating system is initialized and engine code is started.
This takes about 15 seconds. The Xerox logo is displayed.
8. Print Engine Self Test (PEST) diagnostics are then performed. These test
the heaters, clutches, motors and solenoids. As each clutch is tested, you hear clicking with four high tones as each motor is tested. This test takes about 30 seconds.
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I have found out the 2 flashes indicate an error with the vertical output IC / circuit.
after watching tv for a few minutes, the tv shuts off and flashes the red power light 3 times then repeats with 2 times and repeats 2 times and so on and so on, sounds like this happens on alot of these 32RF52S 32 tv's, what is the problem?
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