Texas Instrument Technology

WARNING: Service should not be attempted by anyone unfamiliar with the necessary precautions on this projector. The following are the necessary precautions to be observed before servicing this chassis.

1. An isolation Transformer should be connected in the power line between the projector and the AC line before any service is performed on the projector.

2. When replacing a chassis in the cabinet, always be certain that all the protective devices are put back in place, such as; non-metallic control knobs, insulating covers, shields, isolation resistor-capacitor network etc.

3. Before returning the set to the customer, always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as terminals, screwheads, metal overlays, control shafts etc. to be sure the set is safe to operate without danger of electrical shock. Plug the AC line cord directly into a AC outlet (do not use a line isolation transformer during this check). Use an AC voltmeter having 5000-ohm per volt or more sensitivity in the following manner: Connect a 1500-ohm 10W resistor, paralleled by a 0.15-MFD, AC type capacitor, between a known good earth exposed metallic parts, one at a time. Measure the AC voltage across the combination of 1500-ohm resistor and 0.15-MFD capacitor. Reverse the AC plug at the AC outlet and repeat AC voltage measurements for each exposed metallic part. Voltage measured must not exceed 5.25V(rms). This corresponds to 3.5mA(AC). Any value exceeding this limit constitutes a potential shock hazard and must be corrected immediately.

ground (water pipe, conduit, etc.) and the AC VOLTMETER

ground (water pipe, conduit, etc.) and the AC VOLTMETER

Good earth ground such as a water pipe, conduit, etc.

Place this probe on each exposed metallic part.

1500 ohm

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