I was just thinking of some of the scenarios which I've been in while troubleshooting electrical equipment.
More often than not, my need for access to TWO test points in a circuit is restricted in some way.
- Whether it's because of being somehow blocked by the unit's enclosure,
- whether it's because my test leads simply won't reach the test points,
- whether it's due to the type of connections that are used in the circuit...
- or whether it's because I'm NOT really good at standing on ONLY my head while using my hands to maneuver the test leads...with the meter awkwardly sitting sideways in the only possible place I could put it...while trying to avoid knocking it off...and while trying to see it.
Of course, in the last scenario, THAT would generally ALSO include the exact moment when some duffus in the kitchen decides to drop a pan on the floor - at THE VERY MOMENT that I'm making contact with my circuit's test points for a crucial voltage reading in a 480v circuit.
INDEED, some equipment is obviously designed by engineers who offered absolutely NO thought to the fact that their equipment WILL fail at some point.
I'll spare you of the wretched thoughts I have towards engineers.
Many technicians will find these austere situations as a discouragement and therefore take some alternate approach (or just make an assumption) that may lead to an improper diagnosis. I've seen this play out time and time again. In those situations, ultimately some new part gets ordered, lengthy downtime ensues (while awaiting the part), the new part gets received & installed...and then the unit STILL doesn't work.
My point is that technicians must AVOID being deterred by obstacles which encumber you from performing a proper diagnosis, no matter what system or form of energy you're working on. Be it whether you're dealing electricity, gas, steam, water, hydraulics, air, drainage...in a fryer, dish machine, combi-oven, HVAC unit...or a gas heater suspended fifteen feet above the floor.
BY ALL MEANS, observe proper SAFETY procedure. For instance - if another set of hands is needed to do it safely, then reschedule the service call for when you have that help.
For that heater, rent a lift.
On the other hand, there are also many technicians out there that simply never learned (or choose not to use) proper troubleshooting practices. He shows up on a job, get his hands in it, get only so far with it so as to reveal what's not working. THEN, points a crusty, grease-stained finger at it to pronounce that it needs THIS part replaced - without taking his troubleshooting endeavor to the next level.
AND, by the way - it so happens that he's pressured to move on to move on to the next call because he's booked up, so stops there because he's seen this before and that's what always causes it.
ME - to use him as an example...
EXAMPLE: He orders a gas valve for a Reznor heater (one hanging 15' above the floor) because the he saw that the well-concealed and extremely difficult to access pilot burner was getting spark, but wouldn't light.
A heater like this:
More about that example in a moment.
Ultimately, as a technician - YOUR intent and purpose is to troubleshoot so that you're 100% sure that you've identified the exact problem so that you can fix the equipment.
NOW, I'm not any smarter or better than anyone else. However, I'd learned years ago (and also used to teach) a six-step troubleshooting technique while in the military. Along with that, my predecessors had pounded into my head some notion that I should VERIFY whatever diagnosis I make before replacing any parts.
So, personally, I'm 100% sure...that I'm usually right in my diagnosis...about 100% of the time ( ±1%... ). I DO take enough pride in my work that I'll readily profess that my "signature of approval" is on that equipment before I call it GOOD.
That's just a mindset I've learned. I can't do work which contradicts that.
My "name" is on it.
Through my forty years as being a technician in some capacity, I've never forgotten that ever-important step of VERIFICATION.
I always verify - by whatever means that's most suitable.
- By using an ohmmeter after using a voltmeter to find that I should suspect it as faulty.
- By temporarily jumpering it (ONLY while using proper judgment...and not leaving it that way).
- By a visual inspection.
- By sampling or checking the presence (or lack) of another form of energy.
- Or other ways, based upon the situation.
With that in mind, let's go back to the tech in my example who worked on that heater.
EXAMPLE: He replaced the gas valve because the pilot wouldn't light. However, It STILL wouldn't light after the valve was installed. Further exploration proved that gas valve was INDEED supplying gas to the pilot burner, but found that it wouldn't work because the pilot burner orifice was clogged -thereby COMPLETELY blocking gas flow for the burner.
So as you can see, had this tech gone the extra step and VERIFIED his initial diagnosis by actually checking gas flow THROUGH the pilot burner, he would have discovered that his initial diagnosis (or assumption) was incorrect. The gas valve was never at fault.
Therefore, he would've simply cleaned up the pilot, reinstalled it - and the heater would have been up and running TODAY...rather that three weeks from today.
One final point, which fixbear alluded to in a thread here at TechTOWN. To quote what he said:
The one thing I can say about this business, is one must fully understand the manufacturers design, safeties, and intended operation to be good at servicing them. Basically, "How does it work". If you can't answer that before you start, go back to the books. I have spent almost as much time doing research as actually being on site and repairing.
To troubleshoot properly, you've got to learn a unit's system. EVERY aspect of the equipment's operation. Every breath it takes. Every moan it makes.
- Monitor every click... and know why it happened.
- Listen with anticipation for an expected "click"...and explore the reason why it DIDN'T happen.
- EVERYTHING it does from when you turn it on until you turn it off.
- Know what it does after first turning it on...and what should happen even AFTER it's turned off.
- Run it through ALL modes of operation to test it, no matter how simple or mundane the problem was that you were called there to fix.
- LISTEN and WATCH for everything that should happen.
- ...and I could go on.
- Troubleshooting isn't simply seeing a component not working and ordering a replacement component.
- Troubleshooting isn't just going there and using a "shotgun" approach for identifying a problem.
- Troubleshooting isn't just having experienced that problem before, so this is what the problem is.
- Troubleshooting IS truly is a discipline which requires further study and its appropriate application in order to achieve a 100% success rate.
* * * * * * * * * * * * * * * * * * * * * * * * * * * *
FWIW, I went and found that six-step troubleshooting "procedure" that I learned in the military:
Six-Step Troubleshooting Procedure
You may have the job of maintaining or helping to maintain some electrical or electronic unit, subsystem, or system. Some of these jobs may be complex, but even a complex job can be broken down into simple steps. Basically, any repair of electric or electronic equipment should be done in the following order:
1. Symptom recognition. This is the action of recognizing some disorder or malfunction in electronic equipment.
2. Symptom elaboration. Obtaining a more detailed description of the trouble symptom is the purpose of this step.
3. Listing probable faulty functions. This step is applicable to equipment that contains more than one functional area or unit. From the information you have gathered, where could the trouble logically be located?
4. Localizing the faulty function. In this step you determine which of the functional units of the multiunit equipment is actually at fault.
5. Localizing trouble to the circuit. You will do extensive testing in this step to isolate the trouble to a specific circuit.
6. Failure analysis. This step is multipart. Here you determine which part is faulty, repair/replace the part, determine what caused the failure, return the equipment to its proper operating status, and record the necessary information in a recordkeeping book for other maintenance personnel in the future. While not a part of this step, the technician should reorder any parts used in repair of the faulty equipment.
Sometimes you may run into difficulty in finding (or troubleshooting) the problem. Some hints that may help in your efforts are:
Observe the equipment's operation for any and all faults
Check for any defective components with your eyes and nose
Analyze the cause of the failure for a possible underlying problem
Source: Navy Electricity and Electronics Training Series (NEETS), Module 19 - The Technician's Handbook, NETPDTC 1550/41 (Rev 4-00)