FlexRadio Systems FLEX-1500, Service Manual

Page: 14 / 62

Revision 1.0
14
Copyright FlexRadio Systems, 2010-2011
Troubleshooting and Diagnostics
For bench testing the complete unit or RFPA as a stand alone board, it is recommended
that a 13.8 Volt current limited bench supply is used, with the current limiter set to 2.5
Amperes.
If necessary to test a transceiver board as a stand alone board, a holding fixture with
number 4 corner pins can be used to hold the board. A source of reg5.0 Volts,
current limited at 600 mA may be applied in place of the power source jumper on J6, if
present, or P2.
The results from the factory tests built into PowerSDR should provide direction as to any
failures in the radio. The keyboard command to invoke the factory test page in
PowerSDR is Control-Shift-P.
The blue light in the center of the power-on switch is controlled by the CPU. This light
will only light if the CPU has downloaded valid firmware from the EEPROM and has
completed initialization.
If no blue light, check all voltages, including the output of the ded3.3V regulator
feeding the CPU digital power pins, which is separate from the general 3.3V regulator.
If the blue light is present, but the unit will not enumerate on the USB host, check cables,
connectors, and proper voltage output from the ded3.3V regulator (IC28) feeding
the CPU digital power pins.
None of the band pass filters in the transceiver board should have an insertion loss greater
than 6 dB inside the band pass, so signal tracing with an RF signal generator and level
meter or spectrum analyzer is very practical.
Excessive filter loss is usually associated with an incorrect inductance value, or shorted
turns in one or more filter inductors.