Keysight N5221A/22A Service Guide 4-19TroubleshootingFront Panel TroubleshootingA3 Display TestThe display should be bright with all annotations and text readable. The displaytest allows you to check for non-functioning pixels and other problems.What Is a Damaged Pixel?A pixel is a picture element that combines to create the image on the display. Apixel is about the size of a small pin point.A damaged pixel is pixel that has a constant blue, green, red, or blackappearance that will not change.How to Run the Display TestTo run the display test, perform the following:Press UTILITY , then , then , then .A multi-color screen is displayed. Be prepared to look for the symptomsdescribed in “How to Identify a Faulty Display.” Follow the instructions on thescreen.How to Identify a Faulty DisplayA display is considered faulty if:— More than 0.002% of the total pixels have a constant blue, green, red, orblack appearance that will not change.— Three or more consecutive pixels have a constant blue, green, red, or blackappearance that will not change.If the A3 display assembly is determined to be faulty, replace it. Refer to“Removing the A3 Display Assembly and the Touchscreen” on page 7-12.Checking the A2 USB BoardTo verify proper operation of the USB board:— Connect a known good USB device, such as a USB mouse, to a front panelUSB port.— Wait 15 seconds for the analyzer to verify the device connection, and thencheck the operation of the USB device.— If the device performs correctly, the USB board is functioning properly.— If the device does not perform correctly, the USB board is faulty. Refer to“Removing the A2 USB Board” on page 7-10.If the display is dim or dark, refer to “Troubleshooting LCD DisplayProblems” on page 4-14.System Service More Display Test
