
XR12 Troubleshooting Manual
Responding to alarms
Page 1-16
Issue 3.0 2009-07-28
This alarm indicates the PDM duty cycle of exciter B’s modulator drive is too high. Try to reset the
alarm. If the alarm persists, proceed to the steps listed in
.
PDM drive fail
This fault indicates that the PDM drive is inoperative. If the exciter transfer function is set to
auto
,
then the microcontroller will attempt an exciter changeover to the other side. If it cannot complete an
exciter changeover, or if the exciter transfer function is set to
manual
, then this fault will cause a
shutback.
A
PDM Drive Fail
alarm indicates that the PDM drive signal’s duty cycle is too low (pulse width too
narrow). It may be caused by a fault on the interphase PDM driver PWB or the control display PWB's
alarm circuitry. Troubleshoot a
PDM Drive Fail
alarm as follows:
1. The
PDM Drive Fail
alarm initiates an automatic exciter changeover to the standby exciter.
To troubleshoot a defective exciter circuit, set changeover to manual as detailed in
Operating and Maintenance Manual
.
2. If the transmitter successfully switched to the standby exciter, suspect the main exciter's
interphase PDM driver PWB.
3. Use an oscilloscope to measure the voltage at TP6 on the interphase PDM driver PWB. The
indication should have a dc offset of 1.4 V ± 10%. If not suspect the remote interface PWB
or the IBOC/DRM exciter if you are operating in all-digital (HD) mode.
4. Measure the dc voltage at TP1 of the interphase PDM driver PWB. If the voltage is either
0 V (and transmitter not shut back) or 15 V, suspect the control/display PWB.
5. Use an oscilloscope to measure TP2 of the interphase PDM driver PWB. The signal should
be a square wave at the transmitter’s 2f
PDM
frequency (nominal 130 kHz). If not, suspect the
RF synthesizer PWB.
6. Measure the dc voltage at TP3 on the interphase PDM driver PWB. The voltage should be
the B+ voltage multipled by 0.02 ± 10%. If not, suspect the wiring to the B+ distribution
PWB or the exciter interface PWB.
7. If no faults were found in the previous steps, suspect the control/display PWB.
Summary of Contents for XR12
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Page 8: ...XR12 Troubleshooting Manual Table of contents Page viii Issue 3 0 2009 07 28...
Page 12: ...XR12 Troubleshooting Manual Page xii Issue 3 0 2009 07 28...
Page 20: ...XR12 Troubleshooting Manual Page xx Issue 3 0 2009 07 28...
Page 100: ...XR12 Troubleshooting Manual Detailed Circuit Descriptions Page 2 32 Issue 3 0 2009 07 28...
Page 108: ...XR12 Troubleshooting Manual Parts Lists Page 3 8 Issue 3 0 2009 07 28...
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Page 214: ...XR12 Troubleshooting Manual Reading Electrical Schematics Page 5 6 Issue 3 0 2009 07 28...
Page 223: ...Issue 3 1 2014 05 07 SD 9 Figure SD 9 NAPX05E 02 Dynamic Carrier Control PWB Sheet 1of 2...
Page 224: ...Issue 3 1 2014 05 07 SD 10 Figure SD 10 NAPX05E 02 Dynamic Carrier Control PWB Sheet 2 of 2...
Page 233: ...Issue 3 1 2014 05 07 SD 19 Figure SD 19 NAP34A RF Power Module Overall Sheet 1 of 2...
Page 234: ...Issue 3 1 2014 05 07 SD 20 Figure SD 20 NAP34A RF Power Module Modulator Stage Sheet 2 of 2...
Page 235: ...Issue 3 1 2014 05 07 SD 21 Figure SD 21 NAPC150A RF Drive Control PWB Sheet 1 of 3...
Page 236: ...Issue 3 1 2014 05 07 SD 22 Figure SD 22 NAPC150A RF Drive Control PWB Sheet 2 of 3...
Page 237: ...Issue 3 1 2014 05 07 SD 23 Figure SD 23 NAPC150A RF Drive Control PWB Sheet 3 of 3...
Page 238: ...Issue 3 1 2014 05 07 SD 24 Figure SD 24 NASM07H Modulator Assembly...
Page 239: ...Issue 3 1 2014 05 07 SD 25 Figure SD 25 NAA51A 03 RF Amplifier Assembly...
Page 245: ...Issue 3 1 2014 05 07 SD 31 Figure SD 31 NAPS10C RF Drive Power Supply PWB...
Page 248: ...Issue 3 0 2009 07 28 MD 1 Figure MD 1 XR12 Transmitter...
Page 257: ...Issue 3 0 2009 07 28 MD 10 Figure MD 10 NAPP02 01A RF Current Probe PWB...
Page 259: ...Issue 3 0 2009 07 28 MD 12 Figure MD 12 NAFP103 05 Forward Reflected Power Probe A1 DETAIL...
Page 263: ...Issue 3 0 2009 07 28 MD 16 Figure MD 16 NAPC150A RF Drive Control PWB...
Page 265: ...Issue 3 0 2009 07 28 MD 18 Figure MD 18 NASM07H Modulator Assembly...
Page 266: ...Issue 3 0 2009 07 28 MD 19 Figure MD 19 PA Input Output PWB 176 1065 04 and 05...
Page 267: ...Issue 3 0 2009 07 28 MD 20 Figure MD 20 NAA51A 03 RF Amplifier Assembly...
Page 268: ...Issue 3 0 2009 07 28 MD 21 Figure MD 21 NAPI47B Modulator Input Output PWB...
Page 271: ...Issue 3 0 2009 07 28 MD 24 Figure MD 24 Relay Assy 202 7019...
Page 272: ...Issue 3 0 2009 07 28 MD 25 Figure MD 25 Fan Tray 202 7020 J1 B1 B2...
Page 273: ...Issue 3 0 2009 07 28 MD 26 Figure MD 26 NAPS10C RF Drive Power Supply 62 V...
Page 275: ...Issue 3 0 2009 07 28 MD 28 Figure MD 28 Rectifier Assembly 202 7017...
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