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Model CF1926A TV with insufficient vertical height. I replaced c308, c305, c301, c315. voltage was missing from ic501, pin 29; restored with replacement of c301. no help to vertical. voltage was missing from ic501, pin 37. replaced c315, still no voltage pin 37. 9 volt supply is present. ic301: all voltages present & correct, except pin 6, which jumps up when meter lead touches leg, then fades to 1/4 volt. replacing c308, d301, no effect. vertical is 6 inches top & bot short of full screen. Height control works properly. no resistors found bad. 26 volt line good, 9 volt line good. Is ic301 bad? output voltage is 1 volt high at pin 2. Pins 7 and 3 have same voltage, as though d301 might be bad, but replacing it resulted in no change.

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I think you missed one cap. Look for another 1ufd cap close to the jungle chip. It will have the circuit designation in the 300's like the others in the vertical circuit. It is just not located close by. I think that one will fix it.I don't have the service data with me so I can't give you the exact designation.
Dan

Posted on Jun 04, 2008

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This is a vertical deflection problem - possibly a bad capacitor, bad connection, flyback/pumpup diode, or other component. None of these should be very expensive (in a relative sort of way).

If the symptoms change - particularly if they become less severe - as the set warms up, a dried up electrolytic capacitor is most likely. If they get worse, it could be a bad semiconductor. Freeze spray or a heat gun may be useful in identifying the defective component.

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1 Answer

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Dear dc_rock,
These the most common failures for this TV Model VS-5043- VZ3:

1. Check base bias Voltage of Q217, for 0 VDC (BIASED OFF) if .7 VDC (BIASED ON) check C268 (22 UFD 50 V) off C OF Q215 V-Protector on the SIGNAL PCB.

2. Vertical Beam Blanking Active, check PIN 4 of IC401 for 3 VDC. If missing check IC202 (5V REG) PART # 266P932010, on The SIGNAL PCB.

3. Check Pin 6 of IC200 for 9 VDC if low or missing check IC203 Part#
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1 Answer

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Hello: ( 9 blinks on this model indicates an audio problem. Three times indicates you may need service to replace IC501, and IC5002 on the G-Board. It may be better and cheaper for you to just have the G-Board replaced as to replacing individual componets. This is an over-voltage detection issue, and will need to be serviced by an service technician.

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1 Answer

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The problem as you describe it usually means a vertical problem for a standard TV and the solution is either to resolder the pins of the IC or to replace it. I am not familiar with the board layout of your model, but there should be a small flat IC attached to a heat sinh with about 9-11 pins. It may be marked LA7837 or something similar. Try resoldering the pins first. If that fails to resolve the problem, replace the IC.

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1 Answer

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Good Day;

One of these may be your problem:

1. SHUTDOWN CAN BE CAUSED BY NO VERTICAL DEFLECTION. SINCE THE VERTICAL CIRCUIT IS POWERED BY THE SWITCHED POWER SUPPLY THE UNIT MUST BE TURNED ON TO TROUBLESHOOT THE CIRCUIT. THIS CAN BE ACCOMPLISHED BY TEMPORARILY DISCONNECTING THE VERTICAL INPUT TO THE X-PROTECT CIRCUIT. ** TO PREVENT DAMAGE TO THE CRT'S YOU MUST UNPLUG THE CRT PCB'S. ** TO DEFEAT THE X-PROTECT CIRCUIT, UNSOLDER D4A1 LOCATED OFF THE COLLECTOR OF Q4A1. IF THE UNIT POWERS ON AT THIS POINT, YOU HAVE CONFIRMED A VERTICAL FAILURE AS THE CAUSE FOR SHUTDOWN. ** D4A1 MUST BE REINSTALLED IN CIRCUIT TO PREVENT CRT DAMAGE. ** 2.CHECK PIN 1 OF IC401 FOR 10.7VDC. IF LOW OR MISSING CHECK FOR SHORTED D4000 LOCATED OFF PIN 1. (PCB-MAIN) D4000 PART #264P487030 3. CHECK PIN 8 OF IC401 FOR 27.7VDC. IF MISSING CHECK FOR OPEN D955 AND L961 AT S1 TERMINAL OF T902. (PCB-POWER) D955 PART #264P102040 L961 PART #411P012010 4. CHECK FOR DEFECTIVE IC401. IC401 PART #272P239040, OR INSTALL PT# IC-401, THIS KIT CONTAINS CAPACITOR C920, D4000 AND IC401. BE SURE TO MOUNT C920 ON FOIL SIDE OF PCB. 5. EXCESSIVE 130V SUPPLY. CHECK C911 47 UFD 100 V AND C914 47 UFD 50 V, IN THE IC900 CIRCUIT. Good Luck, big IRISH.

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1 Answer

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3 Answers

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The probable defective part is the vertical IC. If changing that does not resolve the problem, check the capacitors in the same circuit. Also, check for the proper voltages at the vertical IC. If the IC is not being fed its power, it won't work either. I don't have a listing for your specific model. If you can post the vertical IC part number (LA7837 for example), I can list the voltages per pin.
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1 Answer

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This model is equipped with a keyboard lock feature; this can be mistaken as a no power condition. To unlock the keyboard press and hold the "menu" button on the front panel for 10 seconds. 2. (Power LED may be on after plug in) check for no less than 4.4 volts DC at pin 3 of PC9A21 on the Power PCB, if low or missing replace PC9A21 part # 268P058020. You can try this first then if don't work still:This model is also equipped with a self-diagnosis feature to help with diagnosis of shutdown problems. To activate this turn the unit on let it shutdown then press the input and menu buttons on the front panel simultaneously and hold them in for 5 seconds after 5 seconds the power LED on the front panel will blink a two digit sequence. This will be one set of blinks a short pause then another set of blinks, this will repeat 5 times. 1 - 2 = no error detected 2 - 1 = X-ray protect (high voltage or beam current) 2 - 2 = Short protect (short protect monitors low voltage supplies) 2 - 3 = Deflection protect (this could be loss of vertical or horizontal deflection) 2 - 4 = Vertical protect (usually loss of vertical from the source) 1. Shutdown at power with self diagnosis error 2-2. Check for open fuses F9A04 and F9A05 part # 283P144080 on the +24 and -24 volt lines. If the fuses are open the convergence output circuit would be suspect. 2. Shutdown at power with self diagnosis error 2-1. At power on check for 12-volts DC at connector KH pin 8, if missing check IC9C51 part # 270P990010 and L9C52 part # 441D009020 on the Signal PCB

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