TV Repair: Common Faults and Solutions.

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Repair Guide: Common Issues and Fixes

Brand	Model	Fault	Detailed Problem
SONY	KV2647R	Dark picture in scrambled cable, cable box side problem	When using a jerrold model 400 addressable converter allscrambled cable channels were dark. looking at the converter output on ascope indicated a wide sync pedestal than on standard reception and 1 or 2horiz lines early, when both cable output and broad
SONY	KV2647R	Shut down, hvr cracked	These units would go into hv shutdown intermittently. thereason is that the hvr block had a hair-line crack. the voltage out ofthe hvr block feeding q505 would increase up to 30vdc at times activatingprotection circuit.
SONY	KV2645R	Dead, replaced fbt	Fbt (2) transformers were replaced the same week on twodifferent units for excessive vibrations or singing. wedging did nothelp.
SONY	KV1920D	Blanking bar at the top of the screen	A blanking bar at the top of the screen approx. 2 inches high.it did not vary with line voltage. tech. had had some initial verticalproblems. found only 33v on collector of q502. obviously 135v was noton d506.
SONY	KV1915	Poor convergence	Cannot adjust b & w tracking, the convergence changes, andthe only way that the set will come close to being in focus is if thecontrol is all the way to one end of its range.
SONY	KV1747R	No centering operation	This unit had the picture centered too far left even afteradjusting the centering tap. shorting l504 in series with the tapprovided enough range.
SONY	KP7220	Faint cross hatch on the screen, replaced d303	This unit had a faint cross hatch superimposed on picture.
SONY	KP5040	No red vertical convergence, replaced crt neck ass'y	The red vertical convergence does not move. found open coilon the crt neck assembly.
SONY	VTX1000R	Hiss noise in audio	Slight hissing noise in audio only on channel 13.
SONY	KX2501	Shut down after warm up, q1520	Unit would go into shut down after warm up. the shut down wastraced to the hold down circuit, where the horizontal osc. output wasdefeated. inspection revealed a voltage being developed at collector ofq1520. all other voltages and devices checked ok.
SONY	KX2501	Dots in picture, replaced crt	With no input signal, even with the brightness and picturecontrols completely off the crt exhibits about 12 white dots distributedin a random pattern over the entire face of the crt. these dots willrandomly burst in a sort of fireworks pattern, dispersi
SONY	KX2501	Unable to control contrast, replaced c1568	Unable to control contrast. using pix control found abl #3transistor reading 3.8vdc, should be 25.2vdc, isolated problem to c1568.capacitor was read 200Ω.
SONY	KX2501	No picture, replaced r761b	Lose video immediately after turn on. traced video info. upto the base of q704 and no further on c board. voltage on collector ofq713 was about 7v dc and it would not allow q707 to conduct. replacingq713 would allow video to be present about 20 second
SONY	KV4100	Parts availability	Referring to page 74 of the s/m, servicer claims that mountedon the capstan shaft above the flywheel there is a plastic gear which isnot shown in the s/m. my manual does not show such a gear either. -hq comments: the plastic gear in question is a part
SONY	KV2648R	Dead, replace r616 and q603	Set would operate for approx. one to two min. it would thenblow the converter out in power supply and the line fuse. found r616open and q603 leaky from collector to emitter.
SONY	KV2648R	Picture distortion, resoldered 135v rectifier	Picture would expand and contract with the setting of thepicture control. there was also video noise in the picture and a highpitched faint arcing sound.
SONY	KV2647R	Snowy picture, replace d012	Unit displayed snow on all channels. inspection revealed b+to prescaler was about 5v dc instead of 6.8v dc. zener diode in basecircuit of 6.8v regulator was defective.
SONY	KV2645R	Sound distortion	Two transformers were replaced the same week on two different units for excessive vibrations or singing. wedging did not help.
SONY	KV2643R	No tuning, replaced c519	No programming any channels on manual or auto. you could setthe stations appear on the screen but they would not be programmed in thememory. during auto program, the neons would not light up in sequence asthe set tuned through the bands, only channel 2
SONY	KV2602	Intermittent shut down, replaced cracked hvr block	This unit would intermittently shut down. the hvr block had acrack across the bottom.