406 Fault Finding of Control Head TM9100 Service Manual© Tait Electronics Limited August 200514.6 Function Key LEDs or Status LEDs FaultyThe function key LEDs (F1 and F4) and the red, green and amber statusLEDs each are controlled by an FPGA signal and a transistor (Q604 toQ608). The brightness level is controlled by two FPGA signals, resulting infour intensity levels (off, low, medium and high).LED Faulty If one of the function key LEDs or status LEDs is faulty:1. Send CCTM command 1001 x 1 (where x is the LED number:0=F1, 1=F4, 2=amber, 3=green, 4=red) to activate the relevantLED.2. Check the resistors R34, R35, and R36 in the paths of the greenLEDs.3. Measure the voltage at the point between the LED and the transistor.If the voltage is incorrect, replace the LED.4. Replace the corresponding transistor.LED Intensity Faulty If the intensity of the LEDs is faulty:1. Send CCTM command 1001 0 1 to activate the LED of the F1 key.2. Send CCTM command 1002 3 to set the LED intensity level to high.Figure 14.5 Circuit diagram of the function key LEDs and status LEDsIND BRIGHT1 R601FPGAIND BRIGHT2LED FUNC 1LED FUNC 4LED IND TXLED IND RXLED IND BUSY3V3R602R603 R604R340D613F1 Key3V3R605R350D614F4 KeyQ604 Q6053V3R609D615RedQ6063V3R612R360D616GreenQ6073V3R616D617AmberQ608R34: 0ΩR35: 0ΩR36: 0ΩD613/Q604 (F1 key LED):D614/Q605 (F4 key LED):D615/Q606 (red status LED):D616/Q607 (green status LED):D617/Q608 (amber status LED):1.87V (on)1.87V (on)1.92V (on)1.87V (on)1.89V (on)1.40V (off)1.40V (off)1.57V (off)1.40V (off)1.48V (off)
