Function Key Leds Or Status Leds Faulty - Tait TM8235 Service Manual

14.6

Function Key LEDs or Status LEDs Faulty

Figure 14.5 Circuit diagram of the function key LEDs and status LEDs
R601
IND BRIGHT1
R602
IND BRIGHT2
FPGA
LED FUNC 1
LED FUNC 4
LED IND TX
LED IND RX
LED IND BUSY
LED Faulty
LED Intensity Faulty
414 Fault Finding of Control Head with Graphical Display
The function key LEDs (
LEDs each are controlled by an FPGA signal and a transistor (Q604 to
Q608). The brightness level is controlled by two FPGA signals, resulting in
four intensity levels (off, low, medium and high).
3V3
R34
0
F1 Key
D613
Q604
R603 R604
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 relevant
LED.
2. Check the resistors R34, R35, and R36 in the paths of the green
LEDs.
R34: 0Ω
R35: 0Ω
R36: 0Ω
3. Measure the voltage at the point between the LED and the transistor.
D613/Q604 (F1 key LED):
D614/Q605 (F4 key LED):
D615/Q606 (red status LED):
D616/Q607 (green status LED):
D617/Q608 (amber status LED):
If the voltage is incorrect, replace the LED.
4. Replace the corresponding transistor.
If the intensity of the LEDs is faulty:
1. Send CCTM command 1001 0 1 to activate the LED of the
2. Send CCTM command 1002 3 to set the LED intensity level to high.
and ) and the red, green and amber status
F1 F4
3V3
3V3
R35
0
F4 Key
D614 Red D615
Q605 Q606
R605 R609
1.87V (on)
1.87V (on)
1.92V (on)
1.87V (on)
1.89V (on)
3V3
3V3
R36
0
D616 Amber D617
Green
Q607 Q608
R612 R616
1.40V (off)
1.40V (off)
1.57V (off)
1.40V (off)
1.48V (off)
F1
TM8100/TM8200 Service Manual
© Tait Electronics Limited June 2006
key.