KV-27S42/27S46/27S66/29AL42/29AL42C/29AL66/ 29AL66C/29SL42/29SL42C/29SL46/29XL42M

SAFETY CHECK-OUT

After correcting the original service problem, perform the following safety checks before releasing the set to the customer:

1.Check the area of your repair for unsoldered or poorly soldered connections. Check the entire board surface for solder splashes and bridges.

2.Check the interboard wiring to ensure that no wires are “pinched” or touching high-wattage resistors.

3.Check that all control knobs, shields, covers, ground straps, and mounting hardware have been replaced. Be absolutely certain that you have replaced all the insulators.

4.Look for unauthorized replacement parts, particularly transistors, that were installed during a previous repair. Point them out to the customer and recommend their replacement.

5.Look for parts which, though functioning, show obvious signs of deterioration. Point them out to the customer and recommend their replacement.

6.Check the line cords for cracks and abrasion. Recommend the replacement of any such line cord to the customer.

7.Check the B+ and HV to see if they are specified values. Make sure your instruments are accurate; be suspicious of your HV meter if sets always have low HV.

8.Check the antenna terminals, metal trim, “metallized” knobs, screws, and all other exposed metal parts for AC leakage. Check leakage as described below.

Leakage Test

The AC leakage from any exposed metal part to earth ground and from all exposed metal parts to any exposed metal part having a return to chassis, must not exceed

0.5mA (500 microampere). Leakage current can be measured by any one of three methods.

1.A commercial leakage tester, such as the Simpson 229 or RCA WT-540A. Follow the manufacturers' instructions to use these instructions.

2.A battery-operated AC milliammeter. The Data Precision 245 digital multimeter is suitable for this job.

3.Measuring the voltage drop across a resistor by means of a VOM or battery-operated AC voltmeter. The “limit” indication is 0.75 V, so analog meters must have an accurate low voltage scale. The Simpson’s 250 and Sanwa SH-63Trd are examples of passive VOMs that are suitable. Nearly all battery- operated digital multimeters that have a 2 VAC range are suitable (see Figure A).

How to Find a Good Earth Ground

A cold-water pipe is guaranteed earth ground; the cover- plate retaining screw on most AC outlet boxes is also at earth ground. If the retaining screw is to be used as your earth ground, verify that it is at ground by measuring the resistance between it and a cold-water pipe with an ohmmeter. The reading should be zero ohms. If a cold- water pipe is not accessible, connect a 60- to 100-watt trouble light (not a neon lamp) between the hot side of the receptacle and the retaining screw. Try both slots, if necessary, to locate the hot side on the line; the lamp should light at normal brilliance if the screw is at ground potential (see Figure B).

Figure A. Using an AC voltmeter to check AC leakage.

Figure B. Checking for earth ground.

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Sony KV-27S42 service manual Safety CHECK-OUT, Leakage Test
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KV-27S42 specifications

The Sony KV-27S42, KV-27S66, and KV-27S46 are notable models within Sony's acclaimed line of Trinitron televisions, which contributed significantly to the brand's reputation for delivering high-quality viewing experiences. These models are characterized by their sturdy construction, vibrant picture quality, and user-friendly features, which made them popular among consumers during their release.

The KV-27S42 model is equipped with Sony's advanced Trinitron technology, offering a flat CRT screen that minimizes glare and enhances color accuracy. With a 27-inch display size, the KV-27S42 is designed to provide an immersive viewing experience without occupying excessive space in the living room. This model also features a variety of input options including composite, S-video, and RF inputs, allowing users to connect multiple devices such as VCRs, DVD players, and gaming consoles effortlessly.

The KV-27S66 model builds upon the strengths of its predecessor with enhancements in audio and video technologies. It features a built-in 2-channel sound system that delivers clear and dynamic audio, complementing the stunning visuals produced by the Trinitron display. The KV-27S66 also includes a digital comb filter, which improves picture sharpness by separating the brightness and color signals, resulting in reduced artifacts and enhanced clarity.

Meanwhile, the KV-27S46 incorporates some of the latest technologies of its time, such as the use of Super Fine Pitch Trinitron technology. This innovation enhances the display's resolution, offering finer detail and more precise color reproduction. The KV-27S46 also supports multiple viewing formats, making it suitable for various video sources, including standard cable and DVDs.

Each of these models is designed with an intuitive on-screen menu that simplifies the navigation of settings, making it easy for users to adjust picture and sound settings to their preferences. Remote control functionality further enhances the user experience, allowing for effortless operation from a distance.

In summary, the Sony KV-27S42, KV-27S66, and KV-27S46 televisions stand out for their historical significance in delivering quality display and audio technologies. With various features that cater to home entertainment needs, these televisions remain a testament to Sony's lasting legacy in the consumer electronics market. While these models may not compete with today's flat-screen technology, they were pioneering products that set the stage for future innovations in television design and performance.
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