2.2 The IBM 7171 ASCII Device Attachment Control Unit - Index of

F-10: Power Indicator does not turn on at Front Panel.If the 7171 is operating normally, the Power Indicator on the front cover (seeFigure 8-1 on page 8-8) lights immediately and the Ready Indicator lights a fewseconds after the Power On ( I ) Switch is activated.If the power indicator does not light, it is an indication that a malfunction exists inthe 7171. If the ready indicator lights, it may mean that the power on indicatorlight is defective and that the 7171 is operational. If the power on light and/orcard indicator lights, turn on for only an instant, proceed to Step 5 below. Ifneither light is on, proceed as follows:1. With the ON-LINE/OFF-LINE switch to OFF-LINE, turn the Power SwitchOFF (0), wait for at least 20 seconds and turn the Power Switch ON ( I ).2. With the Power Switch ON, determine by inspection whether or not the twofans located behind the power supply are running. If you cannot hear them,you may have to remove the air deflector plate above the power supply bytaking out the two thumb screws that secure it to the power supply. MAKESURE THAT THE POWER IS OFF UNTIL AFTER YOU HAVEREMOVED THE AIR DEFLECTOR. You can now observe the fans whileyou are turning power on. If one fan does not turn, replace it with POWEROFF.3. If the fans do not turn, turn the Power Switch OFF (0) and check that the7171 power cable is plugged into an active outlet. If so, check that the powercable inside the 7171 is plugged into the junction box located beside the fansand that the power supply is also plugged into the same box.4. Replace the power supply and turn the Power Switch ON ( I ) to verify correctoperation. If the spare power supply has two metallic shipping plates held inplace with thumb screws on the under side, remove them before installing thesupply.5. If the power light and/or the card indicator lights turn on for only a short timewhen power is turned on, it is an indication that there may be a short somewherein the 7171.a. Turn the Power Switch OFF (0), unplug any half of the cards and turn thePower Switch ON (I).b. If the problem persists, turn the Power Switch OFF (0), unplug the otherhalf of the cards while reseating the first half (this assures proper powersupply regulation) and turn the Power Switch ON (I ).6. If the power now stays on, turn the Power Switch OFF (0) and insert thecards one at a time, turning the Power Switch ON ( I ) after each card isinserted. Continue replacing one card at a time until you find the card that iscausing the short, replace that card.7. If the problem still persists, replace the power supply.8. If you are unable to continue, invoke your Support Structure.8-12 IBM 7171 Reference Manual and Programming Guide