Chapter 13
661
Display/Power Supply Section
A6 Power Supply Assembly
Supply Restarting Every 1.5 Seconds (Kick Start)
See function blocks G, H and L of A6 power supply schematic diagram
in the component-level information binder.
If there is a short on the power supply or on one of the other assemblies,
the power supply will attempt to "kick start." (Every 1.5 seconds the
supply will attempt to start, but will be shut down by a fault condition.)
The kick start and bias circuits provide power for the control circuitry
during power-up. The kick start circuitry is an RC oscillator which
emits a 200 ms pulse every 1.5 seconds. These pulses switch current
from the Input Rectifier through Q201 to charge C201. When the power
supply is up, a winding on T103 provides power to the control circuitry.
This voltage is high enough to keep Q201 turned off.
1. Monitor the waveforms at TP206 and TP208 simultaneously on an
oscilloscope.
2. If the signal at TP208 goes high before the signal at TP206 goes low,
an overcurrent condition has been detected. Suspect a short in the
secondary (output rectifier, voltage regulators, or another assembly).
Low Voltage Supplies
1. Connect the negative lead of a DVM to A6TP301.
2. Check A6TP302 for +15 Vdc.
3. Check A6TP303 for
−
15 Vdc.
4. Check A6TP304 for +28 Vdc.
5. Check A6TP305 for
−
12.6 Vdc.
6. Check A6TP308 for +5 Vdc.
7. If the voltages measured above are correct but the power supply
LEDs on the A2 controller assembly are not lit, check W1.
8. If the voltages are low, disconnect W1 from A6J1 and measure the
test point voltages again. Unless a dummy load is connected to the
A6 power supply, the voltages should return to their nominal
voltages but be unregulated.
9. If the voltages do not return to near their nominal range, the A6
power supply is probably at fault.
10.If the +5 V supply is low, suspect the +5 V regulator or the feedback
circuit. To check the feedback circuit, measure the voltage of the
+5 V reference (U305 pin 6) and the
±
5 V references to the voltage
regulators (U306B pin 7 and U306D pin 14).
11.Check output of U306A pin 1. If the feedback circuit is working
properly, the output of U306A should be near +13 Vdc.
Содержание 8564EC
Страница 17: ...25 1 General Information ...
Страница 37: ...47 2 Adjustment Diagnostic Software ...
Страница 55: ...Chapter 2 65 Adjustment Diagnostic Software 2 LO Frequency Figure 2 2 LO Frequency Adjustment Locations ...
Страница 57: ...Chapter 2 67 Adjustment Diagnostic Software 3 YTO FM Coil Figure 2 3 YTO FM Coil Adjustment Locations ...
Страница 77: ...89 3 Manual Adjustment Procedures ...
Страница 129: ...161 3a Manual Adjustment Procedures 3335A Source not Available ...
Страница 142: ...175 4 Assembly Replacement ...
Страница 151: ...184 Chapter4 Assembly Replacement Procedure 2 A1 Front Frame A18 LCD Figure 4 2 LCD Assembly Exploded View ...
Страница 163: ...Chapter 4 205 Assembly Replacement Procedure 5 A2 A3 A4 and A5 Assemblies Figure 4 10 Assembly Cables 2 of 3 ...
Страница 166: ...208 Chapter4 Assembly Replacement Procedure 5 A2 A3 A4 and A5 Assemblies Figure 4 14 GPIB and A1A1 W1 Cable Placement ...
Страница 168: ...210 Chapter4 Assembly Replacement Procedure 6 A6 Power Supply Assembly Figure 4 15 Power Supply Cover ...
Страница 176: ...226 Chapter4 Assembly Replacement A9 Input Attenuator Figure 4 22 A9 and A10 A12 Mounting Screws ...
Страница 179: ...Chapter 4 229 Assembly Replacement A11 YTO Figure 4 23 A11 Mounting Screws at Right Side Frame ...
Страница 183: ...Chapter 4 233 Assembly Replacement Procedure 8 A14 and A15 Assemblies Figure 4 25 A14 and A15 Assembly Cables ...
Страница 190: ...Chapter 4 243 Assembly Replacement Procedure 11 Rear Frame Rear Dress Panel Figure 4 29 A6 Power Supply Cover ...
Страница 194: ...Chapter 4 257 Assembly Replacement Procedure 13 A21 OCXO Figure 4 34 A21 OCXO Mounting Screws ...
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Страница 229: ...308 Chapter6 Major Assembly and Cable Locations Introduction Figure 6 3 Top View A2 A3 A4 and A5 Unfolded ...
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Страница 234: ...315 7 General Troubleshooting ...
Страница 238: ...Chapter 7 319 General Troubleshooting Introduction Figure 7 2 Ribbon Cable Connections 1 of 3 ...
Страница 239: ...320 Chapter7 General Troubleshooting Introduction Figure 7 3 Ribbon Cable Connections 2 of 3 ...
Страница 242: ...Chapter 7 323 General Troubleshooting Introduction Figure 7 5 Service Cal Data Menu ...
Страница 271: ...352 Chapter7 General Troubleshooting Block Diagram Description Figure 7 6 Functional Sections ...
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Страница 356: ...Chapter 9 461 IF Section A5 IF Assembly Figure 9 13 Detailed IF Adjust Signature 5 ...
Страница 358: ...Chapter 9 463 IF Section A5 IF Assembly Figure 9 14 Noisy Signature Figure 9 15 Noise with Correct Shape ...
Страница 359: ...464 Chapter9 IF Section A5 IF Assembly Figure 9 16 Region B Amplitude Variation Figure 9 17 Region B Amplitude Offset ...
Страница 369: ...474 Chapter9 IF Section Cal Oscillator P O A4 Assembly Figure 9 21 Output Waveform 10 kHz Resolution Bandwidth ...
Страница 370: ...Chapter 9 475 IF Section Cal Oscillator P O A4 Assembly Figure 9 22 Output Waveform 3 kHz Resolution Bandwidth ...
Страница 371: ...476 Chapter9 IF Section Cal Oscillator P O A4 Assembly Figure 9 23 Output Waveform 1 kHz Resolution Bandwidth ...
Страница 372: ...Chapter 9 477 IF Section Cal Oscillator P O A4 Assembly Figure 9 24 Output Waveform 300 Hz Resolution Bandwidth ...
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Страница 394: ...521 11 Synthesizer Section ...
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