Noblex 21TC647 Service Manual

Contents

Noblex 21TC647 Service Manual Manual pdf 18 page image

-18-TUNERUNITIC501VERT. DEF.Q432HORIZ. OUTT401FBTService AdjustmentsMAIN BOARDFollowing adjustments are not required to readjust when replacing the memory IC.(1) Receive the monochrome circular pattern.(2) Set the brightness and contrast to maximum.(3) If the picture is too wide, or narrow, cut or short the “AJ1” on the main unit. When AJ1 is shorted, the horizontal widthincrease. When AJ1 is cut, the horizontal width decrease.Important note: If the AJ1 is cut, it’s gap must be more than 5mm to prevent sparks.HORIZ. WIDTH AND HIGH VOLTAGE CHECK(1) Receive the monochrome circular pattern.(2) Set the brightness to normal and contrast to maximum.(3) Adjust the focus control on the F.B.T. for the best focus on the screen centre.FOCUS ADJUSTMENTF.B.T.AJ1(4) Connect a high voltage probe to anode lead of the picture tube.(5) The high voltage must be 14”=21KV ± 1KV / 20”,21”=25KV ± 1KV / 29”=26.5KV ± 1KV and less than14”=25KV / 20”,21”=27.5KV / 29”=29.5KV at 0 beam current (Brightnees and contrast minimum setting).Note: If the picture tube is replaced, check the high voltage. The horiz. width adjustment affects the high voltage.Therefore, re-check the high voltage.FOUCUS VR(Upper side)more than 5mmAJ1This TV set has a built-in power supply protection circuit.It is provided to protect the TV set in case of a power supply circuit malfunctions. When something abnormalityoccurs during TV reception, the TV set goes to the stand-by mode.When an abnormality occurs during TV reception, it causes pin 33 of the CPU to go continually Low(less than0.75V) for about one second. The CPU detects that this has occurred and outputs the signal from pin 8 toswitch off the power supply lines.Releasing the protective circuit and restoring power supplyTo release the protective circuit and restore power supply, turn the power to the TV set OFF and then ON againvia either the main power switch or the ON-OFF button on the remote control. This will work only if the powersupply trouble was temporary. If there is permanent trouble such as a damaged circuit, power cannot berestored and the circuit will have to be repaired.n Protection Circuit