Troubleshooting technique (part 3)

by admin on December 5, 2017

(…continued)As I mentioned at the end of the last post, I’ve never owned an electronic repair shop.  In addition to all the things I mentioned in that post, I’ve worked in the military aboard nuclear submarines, I’ve worked in the chemical industry and the semiconductor industry.  In every case, the success of the organization has come down to the ability to doing the right thing, correctly, the first time, every time.

I can’t imagine any organization or business that wouldn’t have

the same basic requirements.  The thing that makes a repair shop different from a production based business is that the starting point will not always be the same.  So whether you are repairing cars, small engines, electronics, appliances, bicycles, whatever, you need to know where you are starting from.  Get as much information from the customer as possible:

  • My garden tiller is hard to start.  Once it starts, it runs fine for about 10 minutes at which point it stalls if it is taken past half throttle.   If it is picked up so that the engine can run unloaded, it runs fine.  Again, once loaded it bogs down and quits. I’ve cleaned the air filter, fuel filter and spark plug.
  • The TV works fine for some period of time and then just shuts itself off.  If turned back on, it makes a loud screeching sound for about a second and then runs.  It will shut itself off again, in less time than before. This continues with the time getting shorter and shorter till it gets to the point that it runs for about 6 minutes max.
  • The dryer won’t turn.  I can hear the motor running and it blows air but the drum won’t turn…
  • The computer boots but the shuts off after 15 minutes.  When first restarted it goes to “safe” mode.

Questions? Let’s ask questions!!

Don’t be shy about asking questions.  When you go to the doctors office because you don’t feel well, they don’t just give you a shot and send you home.  They ask you questions about your symptoms, they take some objective information about you like:

  • Height
  • Weight
  • Blood Pressure
  • Pulse
  • Temperature

When you get to the doctor, who’s seen all the information, they usually start with an open ended question like “I see from the notes that this started several days ago, describe how you feel now…” All the while, they’re looking in your ears, nose, throat and perhaps listening to your heart and lungs.  They then probably ask more specific questions:

  • Is it only on the right side?
  • Always on the right or does it “move around”?
  • Does the intensity change?

In some respects, the doctor’s job is easier.  They can ask questions to get information.  The questions can be in random order.  As an electronics repairer, you get one chance to ask questions (usually) and the answers tend to be less than definitive.  You can’t talk to the device, you have to probe, prod and investigate.  Back we go…

Beginning the repair

Based on the symptoms, you would want to ask additional questions, perhaps, or just dive right in.  The thing you want to develop is a troubleshooting matrix.  What I mean by this is something that reminds you of what to check first.  Just like the owners manuals for most appliances that tell you go over the simple things first (my washing machines manual):

  • Is it plugged in?
  • Is the circuit breaker turned on?
  • Is the water turned on?
  • Is the lid/door shut?
  • Is the load unbalanced?
  • Is the child lock activated?

If you are going to run an electronics shop the most common complaint will be:

It won’t turn on

You want to check the obvious and simple things quickly as you don’t want to march off down the wrong path and start removing components when the thing just needed a new fuse.  The perfect examples I have of this are:

  • A friends’ toaster oven quit working. It turned out to be the thermal fuse.  Trouble shooting time was  under 10 minutes.
  • Another friends’ toaster quit working.  The problem ended up being that the line cord had broken internally. Trouble shooting time 2.5 hours.

In one case, you can tell your customer that you want $25 for the repair.  In the other case, if you tell them $200 to repair, they’ll laugh and go buy a new one.  In the second case, if the trouble shooting had started with: is there power inside the toaster?; the time would have been substantially less.


So the thing you want to have is a logic diagram that has you check the common things quickly & thoroughly.  Here is your homework assignment:  Make yourself a troubleshooting logic diagram that covers the first part of a repair, isolating a power problem.

At the below left is a sample logic diagram. It represents entering a room where you want to turn on a lamp that is connected to the wall switch next to the entrance doorway.  It is not all inclusive, (it never asks if the power is on to the room circuit), but it give you an idea of the overall thought process for getting the light illuminated in the room.  Click on the image to view it full size.

troublechart_7 I hope this helps you with your diagram. Don’t worry about getting it perfect at this point, don’t worry if you only have a couple of things to check.  The important thing is to start thinking about it and documenting (writing it down) your thought process.  The next thing we’ll create is a troubleshooting checklist, based on this diagram.

Additionally, we’ll create a troubleshooting log.  This will be a uniform way of writing down what it is that you have done and what the results are.  For involved, complex,  troubleshooting this is one of the most important things to have.  Why?  If the problem is complex enough that you can’t solve it in one session, you’ll want to be able to easily remember where you were and what you did or didn’t do.  Or, more likely, if you are just starting out you have to do everything.  You have to answer the phone, you have to answer the door and deal with whatever distractions come your way.  If the distraction is important, you may decide to keep dealing with it, or with something related to it, rather than resuming your troubleshooting immediately.  Having a consistent way of doing the troubleshooting and documenting it will be helpful.  Looking to the future, when you aren’t the one answering the phones, you will likely have an apprentice or two.  If they get stuck or can’t figure something out, it will be immensely easier for you to troubleshoot if you have a well documented log.  Or perhaps you want the two or three apprentices to trade off on their troubleshooting, again this will be a useful tool. 

OK, write up your diagram.

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