1 / 23

ECE 2799 Electronic Troubleshooting Strategies

ECE 2799 Electronic Troubleshooting Strategies. Prof. Bitar Last Update: 04/15/10. Electronic Troubleshooting Strategies. Divide and Conquer Bait and Switch Time Warp Wiggle Test Cut Out the Middle Man Show Me the Voltage - Open Circuit Voltage Test (OCVT)

rupali
Download Presentation

ECE 2799 Electronic Troubleshooting Strategies

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ECE 2799 Electronic Troubleshooting Strategies Prof. Bitar Last Update: 04/15/10

  2. Electronic Troubleshooting Strategies • Divide and Conquer • Bait and Switch • Time Warp • Wiggle Test • Cut Out the Middle Man • Show Me the Voltage - Open Circuit Voltage Test (OCVT) • Follow the Current - Short Circuit Current Test (SCCT) • Lose Control (Feedback Systems)

  3. 1. “Divide and Conquer” • Isolate each Block of a System • Verify the Power to each Block • Verify the DC Bias • Verify the Proper Signal Input and Output • Applies to Breadboard • Applies to Simulation • Applies to Prototype Construction

  4. Remember this circuit from ECE 2011? Acoustic Sensor High Pass Filter Amplifier (Gain=75) Peak Detector Comparator LED

  5. And How Neatly You Laid it Out…

  6. “The Clapper” – DC Bias Questions… • DC Bias Questions: • What average DC voltage would you expect to measure at nodes V1, V2, V3, and V4? • If V1 = 0V, what could be wrong? What if V1 = 9V? • If V3 = 7.5VDC (or -7.5V), what could cause this? • If the LED is on all the time, what could cause this? • What if the LED is OFF all of the time?

  7. Signal Path Questions… • Signal Path Questions: • Can you anticipate what the signals V1, V2, V3 and V4 should look like on a scope? Qualitatively? Quantitatively? • What is similar about V1 & V2? What is different? • How about V2 & V3? • V3 & V4? • What about the final output?

  8. Voltage Waveforms …

  9. 2. “Bait and Switch” • Substitute for Sensor Input • Potentiometer • Variable Power Supply • Thevenin Equivalent • Substitute for Load Output • Equivalent Load Impedance (Resistance) • Can Apply I/O Substitution to all Functional Blocks • Be Sure to Match I/O Resistance (RIN and ROUT)

  10. What could replace the microphone for testing purposes? • Things to Consider: • DC Bias • Amplitude of AC Signal • Internal Source Impedance

  11. Consult the Spec Sheet

  12. Possible Simulation Model

  13. Repeat for Output Speaker Source: www.digikey.com

  14. Possible Speaker Models • Under what conditions would you use the simper model? Or the more complex one? • In lab, if using a “Dummy Load” what concerns should be considered?

  15. 3. “Time Warp” • Applies to Timing Functions Governed by: • RC Time Constants • Crystal Oscillators • Digital Counters

  16. LM555 Timer Example Source: www.national.com

  17. 4. “Wiggle Test” • Intermittent Mechanical Connections • #1 Cause of Electronic Troubleshooting Problems • Ford “Wiggle Test” • Be Methodical • Isolate and Stress Each Connection

  18. 5. “Cut Out the Middle Man” • Applies to Multiple Connection Systems • Apply Bypass Techniques to Isolate Problems • Often Applied to Vehicle Harnesses and House Wiring

  19. 6. “Show Me the Voltage” Open Circuit Voltage Test (OCVT) • In a Series Circuit the Greatest Voltage Drop Occurs Across the Largest Resistance • Therefore, an Open Circuit will Have the Most Voltage Across It

  20. Open Circuit Voltage Example

  21. 7. “Follow the Current”Short Circuit Current Test (SCCT) • In a Parallel Circuit the Greatest Current Flows Through the Smallest Resistance • Therefore, a Short Circuit will Have the Most Current Through It • Use the Current Limiting Feature of your Power Supply to Prevent Damage to Components

  22. Short Circuit Current Example

  23. 8. “Lose Control” • Applies to Systems With Feedback • Cut the Control • Substitute Test Control Signal • Verify Proper Feedback Signal • Watch Out for System Runaway!

More Related