Symptoms - Repeated crowbar tripping
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Board discoloration and overheated wiring. -
Screw was welded in capacitor terminal and forced out.
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Underside of board. -
Close up showing heat damage.
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Heat damage to 100,000 uF cap. -
Unhealthy LM723 filter capacitor.
Rebuild Process
| 1. Replace all electrolytic capacitors (obtain 100,000 uF cap from Astron). |
| 2. Add spacer between terminal screw heads and lugs to prevent screw bottoming out before fully tightened. |
| 3. Replace pass transistors. |
| 4. Replace LM723 Regulator. |
| 5. Add frequency compensation capacitor to LM723 circuit. |
| 6. Replace negative terminal connectors and remove damaged wiring. |
| 7. Clean and refurbish damaged contact area on board. |
| 8. Float negative output terminal by removing chassis connection. |
| 9. Add MOVs across all three AC leads. |
| 10. Check and resolder bad collector leads (heavy wire) on pass transistors (1 of 8 bad). |
Sites with good information on Astron Power Supplies
| repeater-builder.com |
| Introductory Information on Astron™ power supplies |
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