Carrier 42NQV025H Service Manual

Contents

– 67 –CAUTIONA high voltage (equivalent to the supply voltage) is also energized to ground through thesensors, PMV and other low-voltage circuits. The sensor leads and other wires are coveredwith insulated tubes for protection. Nevertheless, care must be taken to ensure that thesewires are not pinched.Take sufficient care to avoid directly touching any of the circuit parts without first turning offthe power.At times such as when the circuit board is to be replaced, place the circuit board assembly ina vertical position.Laying the board flat on an electrically conductive object (such as the top panel of the air conditioner'soutdoor unit) while a charge is still retained by the electrolytic capacitors of the inverter's main circuit maycause short-circuiting between the electrolytic capacitors and secondary circuit components and result indamage to the components.Sensor leadsDo NOT lay the circuit board assembly flat.u Precautions when inspecting the control section of the outdoor unitNOTE :A large-capacity electrolytic capacitor is used in the outdoor unit controller (inverter). Therefore, if the powersupply is turned off, charge (charging voltage DC280 to 380V) remains and discharging takes a lot of time.After turning off the power source, if touching the charging section before discharging, an electrical shock maybe caused. Discharge the electrolytic capacitor completely by using soldering iron, etc.< Discharging method >1. Remove the inverter cover (plating) by opening four mounting claws.2. As shown below, connect the discharge resistance (approx. 100Ω40W) or plug of the soldering iron tovoltage between + – terminals of the C14 (“CAUTION HIGH VOLTAGE” is indicated.) electrolytic capacitor(500μF/400V or 760μF/400V) on P.C. board, and then perform discharging.Fig. 11-2Discharging position(Discharging period10 seconds or more)Plug ofsoldering ironInverter coverP. C. board(Soldered surface)Fig. 11-3FILE NO. SVM-07013