HVAC School - For Techs, By Techs
Q&A - Circuit Board Troubleshooting - Short #230
· Summarized
Key takeaways
- Understanding the basic components of circuit boards is important for effective troubleshooting.
- A thorough understanding of inputs, outputs, and the sequence of operations is crucial in diagnosing issues with circuit boards.
- Visual inspections for signs of damage can help identify problems before deeming the board itself faulty.
- Utilizing manufacturer's literature and recommended educational resources can enhance your troubleshooting skills.
Summary
Understanding Circuit Boards
This episode begins with Bryan addressing a commonly asked question about how to check circuit boards. The complexity arises from the fact that circuit boards can greatly differ by model and manufacturer. However, several key components like microprocessors, diodes, relays, capacitors, and transformers remain consistent across many boards. Bryan emphasizes that a basic understanding of these components is crucial to diagnosing issues.
Inputs, Outputs, and Sequences of Operation
Bryan explains that diagnosing circuit boards revolves around understanding their inputs, outputs, and sequences of operation. He illustrates this with a furnace integrated circuit, demonstrating how the sequence determines whether the system proceeds based on the flame rectification process. Proper grounding and component placement are often overlooked factors responsible for common misdiagnoses.
Visual Inspection and Techniques
The podcast discusses the importance of visual inspection in troubleshooting. Many issues can be identified through physical signs such as bloated capacitors or insect nests. Bryan advocates becoming a 'master of the obvious' and stresses the significance of checking the manufacturer's literature as a vital diagnostic tool.
Recommended Resources and Further Learning
Bryan suggests two foundational books for HVAC technicians looking to deepen their understanding: "HVAC Control Systems" by Ronnie Auvil and "Electricity for Refrigeration, Heating, and Air Conditioning" by Russell Smith. He also encourages hands-on practice, logical analysis, and employing the proper tools while troubleshooting.
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Show notes
In this short Q&A podcast episode, Bryan answers a listener-submitted question about circuit board troubleshooting: is there a quick way to learn how to check circuit boards, and if so, where are those resources?
A circuit board is a bunch of components put together on a printed circuit board (PCB). There isn't a lot of helpful universal information about circuit boards available, as they vary quite a bit by model and manufacturer. However, many of the basic components will be the same across circuit boards: microprocessors, diodes, relays, capacitors, and transformers. If you understand what these are on their own, that will help you understand what they do in circuit boards.
You mostly need to know the inputs, outputs, and sequence of operation of a circuit board to diagnose it. The sequence of operation tells you when certain things are supposed to happen, such as in an integrated furnace control (IFC); the flame rectification process is a classic example. If the flame can be proven, the operation continues; if it can't be proven, then that will cause a lockout (possibly due to improper grounding or poor placement and NOT necessarily because of the board).
A lot of issues with the board can be diagnosed if you understand the inputs and outputs (e.g., 24v signals) or observe it with your senses, such as bloated capacitors or ant nests. Becoming a master of the obvious and checking the manufacturer's literature are the top two things you can do to diagnose circuit boards.
HVAC Control Systems by Ronnie Auvil
Electricity for Refrigeration, Heating, and Air Conditioning by Russell Smith
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