TM  10-3930-638-24&P 3-9. ALTERNATOR TROUBLESHOOTING MALFUNCTION TEST  OR  INSPECTION CORRECTIVE  ACTION 1. IMPROPER OUTPUT VOLTAGE Step 1. Step  2. Connect test set-up to alternator as illustrated. Slowly  increase  alternator  speed  and  observe  voltmeter reading. a. If voltmeter reading is uncontrolled with speed, and increases above 31 Vdc, check alternator field wind- ing and regulator (para 3-12). b. If voltmeter indicates battery voltage (no increase in voltage), proceed to step 2. c.  If  voltmeter  reading  increases  (greater  than  battery voltage and less than 31 Vdc), proceed to MAL- FUNCTION 2 (IMPROPER OUTPUT CURRENT). CAUTION Tab is within 3/4 inch of casting surface. Do not force screwdriv- er deeper than one inch into alternator end frame. Insert screwdriver into test hole in end frame and ground tab as shown; then repeat step  1. a. If voltmeter indicates battery voltage (no increase in voltage), check rotor, stator, diode trio, rectifier bridge,  and  regulator  mounting  screws  (para  3-12). b.  If  voltmeter  reading  increases,  replace  the  regulator (para  3-12). 3-89