Tait T2004 System Manual page 58

58 Part B T2004 Control Heads
Microprocessor
Check reset line U14 pin 1 is at 5V.
Use oscilloscope to check for 4MHz oscillation on crystal X2 or resistor
R104.
With micromatch cable on J5 removed, switch on control head with any
key held down. On power up the display should always show software
version number (2372A510). When key is released, all display segments
and LEDs should flash.
Audio
Transmit on microphone and apply audio (E.G. whistle into
microphone), check for approx. -15dBm line audio on RLY2 pins 7 and
8. Radio should enter transmit mode and have normal TX deviation.
"TX" should appear on the LCD.
With the radio in receive mode, generate a test signal of -70dBm RF
level, 60% system deviation (1.5kHz for narrow band, 3kHz for wide
band). Check for approx. -10dBm line audio at C2. Check Q1 base is at
0V, so PA is not muted. Check that audio level into PA on U1 pin 7
varies with volume control. Check for high level audio output on U1 pin
2.
Global mute
Ensure link JP1 is fitted to enable global mute.
When not transmitting and microphone off hook (hang up stud not
earthed), check that JP1 is at 5V.
With microphone on hook (hang up stud connected to 0V), check that
JP1 is at 0V.
Temporarily fit a 1k ohm resistor between JP1 and U22 pin 1. Make
radio receive a test signal and adjust volume so audio can be heard in
control head speaker while microphone is off hook. Speaker should mute
when microphone is placed on hook. Remove link resistor when
finished.
Data
Turn radio off then on using control head volume switch. Use
oscilloscope to check for 5V TTL data on U21 pin 1. Note that data only
lasts a few seconds after power on.
After power up, confirm that key presses on control head appear as 5V
TTL data on U19 pin 4. Connect oscilloscope channel 1 on J5 pin 1,
channel 2 on J5 pin 2. Verify differential mode data exists on RS485 line
when keys are pressed.
PC programming
Connect T2000 programming cable to microphone socket, check for
approx. 13.8V on microphone socket S10 pin 1.
Verify that radio can be read correctly with appropriate radio
programming software.
T2004 Multi-Control Head System Manual
© Tait Electronics Ltd May 2004