User Manual
MT-4E VHF & UHF Receiver & Transmitter Instruction Manual
IM08-MT-4E-TXRX Project 1106
Hardware Tuning and Troubleshooting
20
Transmitter Main Board
Check the following test points on the Transmitter Main Board:
Test Point Signal Monitored Typical voltage
TP1 Voltage from motherboard +13.8 VDC line +10 to +17 VDC
TP2 Regulated +9.5 VDC from motherboard +9.5 VDC ± 5 %
TP3 USB connector power +3.0 VDC or +5.0 VDC
TP4 Switched +13.8 VDC line from front panel switch +10 to +17 VDC
Test Points are shown on the MT-4E Transmitter Jumper and Test Point Locator Illustrations.
If the test point voltages are within the specied range, it is most likely that the Transmitter Main
Board is not the source of problem. Proceed to the following step:
Synthesizer and UDB Modules
The Synthesizer module and UDB are bound together through their communication link. At this level
of fault diagnosis it is not feasible to isolate the problem between two units.
If the transmitter front panel NORMAL/OFF/ KEY TX switch is set from the OFF position to the
NORMAL position and the two front panel LEDs stay on, check that the Synthesizer and the UDB
are properly seated on the Transmitter Main Board and check the following test points on the UDB
(to access the UDB, the Amplifer sub-assembly and the shield lid covering the UDB will need to be
removed as shown on the MT-4E Transmitter Amplier Removed View):
Test Point Signal Monitored Typical Voltage
TP2 Logic power +3.3 VDC ± 5 %
TP3 DSP core supply +1.2 VDC ± 5 %
TP4 CPLD core supply +1.8 VDC ± 5 %
Test Points are shown on the MT-4E Transmitter Jumper and Test Point Locator Illustrations.
If the UDB voltages are not within the specied tolerances, the Transmitter Main Board (that
supplies these voltages to the UDB) is most likely faulty. If the UDB voltages are within the specied
tolerances, it is most likely that the synthesizer or the UDB or both are faulty. The fault may be
associated with the synthesizer code, the DSP Code or both.