Dell Inspiron 14 Plus 7420 Service Manual - Page 6

5. Remove any media card and optical disk from your computer, if applicable. 6. Enter the service mode, if you are able to power on your computer. Service Mode Service Mode is used to cut-off power, without disconnecting battery cable from system board prior conducting repairs in the computer. CAUTION: If you are unable to turn on the computer to put it into Service Mode or the computer does not support Service Mode then proceed to disconnect the battery cable. To disconnect the battery cable, follow the steps in Removing the battery. NOTE: Ensure that your computer is shut down and the AC adapter is disconnected. a. Hold key on the keyboard and press the power button for 3 seconds or until the Dell logo appears on the screen. b. Press any key to continue. c. If the AC adapter is not disconnected, a message prompting you to remove the AC adapter appears on the screen. Remove the AC adapter and then press any key to continue the Service Mode procedure. The Service Mode procedure automatically skips the following step if the Owner Tag of the computer is not set up in advance by the user. d. When the ready-to-proceed message appears on the screen, press any key to proceed. The computer emits three short beeps and shuts down immediately. e. Once the computer shuts down, it has successfully entered Service Mode. NOTE: If you are unable to power on your computer or unable to enter service mode skip this process. Radiation Exposure Statement This device meets the government's requirements for exposure to radio waves. This device is designed and manufactured not to exceed the emission limits for exposure to radio frequency (RF) energy set by the Federal Communications Commission (FCC) of the U.S. Government. The exposure standard for wireless device employs a unit of measurement known as the Specific Absorption Rate, or SAR. The SAR limit set by the FCC is 1.6 W NOTE: Tests for SAR are conducted using standard operating positions accepted by the FCC with the device transmitting at its highest certified power level in all tested frequency bands. Electrostatic discharge-ESD protection ESD is a major concern when you handle electronic components, especially sensitive components such as expansion cards, processors, memory DIMMs, and system boards. Very slight charges can damage circuits in ways that may not be obvious, such as intermittent problems or a shortened product life span. As the industry pushes for lower power requirements and increased density, ESD protection is an increasing concern. Due to the increased density of semiconductors used in recent Dell products, the sensitivity to static damage is now higher than in previous Dell products. For this reason, some previously approved methods of handling parts are no longer applicable. Two recognized types of ESD damage are catastrophic and intermittent failures. ● Catastrophic - Catastrophic failures represent approximately 20 percent of ESD-related failures. The damage causes an immediate and complete loss of device functionality. An example of catastrophic failure is a memory DIMM that has received a static shock and immediately generates a "No POST/No Video" symptom with a beep code emitted for missing or nonfunctional memory. ● Intermittent - Intermittent failures represent approximately 80 percent of ESD-related failures. The high rate of intermittent failures means that most of the time when damage occurs, it is not immediately recognizable. The DIMM receives a static shock, but the tracing is merely weakened and does not immediately produce outward symptoms related to the damage. The weakened trace may take weeks or months to melt, and in the meantime may cause degradation of memory integrity, intermittent memory errors, etc. The more difficult type of damage to recognize and troubleshoot is the intermittent (also called latent or "walking wounded") failure. Perform the following steps to prevent ESD damage: 6 Working inside your computer