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View Full Version : How to Troubleshoot Electronics - For Newbies



dirknerkle
02-23-2013, 01:09 AM
I've searched high and low and... well, I'm not quite 6' tall and I can't bend down too far anymore, so I guess I kinda did a little searching but didn't find anything quite like this thread, which I'm trying to start and which I believe can help those who are just starting out. Many of us are quite advanced in this hobby and it's easy to forget that this hobby can be pretty intimidating to a newbie. We have a lot of troubleshooting posts for specific types of controllers or lights or other gear, but not very many that outline general and obvious troubleshooting tips. So I'm kicking this one off with the information below, in the hope that others may chime in with generic help, not something specific to any particular board, but to the concept of troubleshooting electronics in general. Hopefully, DIYC members will add salient content in an easy-to-read manner. Here goes...

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If you've never built an electronic gizmo before but now have taken the plunge and ordered one of the kits available here at DIYC, you're probably worried that after you've assembled it, it may not work. This thread is (hopefully) going to give you some direction if that should happen.

First of all, be safe. Never plug anything into power until you've thorougly checked your work.

Secondly, don't worry. Most problems can be corrected and, in fact, quite often corrected by very logical solutions. Just have patience. We know that patience is hard to find because you want to plug the device in and see what it'll do. But patience will actually help you here -- it will help you solve the problem and nothing will blow up in the process.

Think Logically. For example, imagine that you just sat down to read the newspaper and the table lamp right next to your easy chair won't turn on. Do you..
Continually flick the switch on and off forty or fifty times, or...
Do you check to see if the light is plugged in?

Next, do you...

Shake the lamp, or whack it a couple times with your hand and then try the switch another dozen times, or...
Do you check to see if the wall switch is turned on, which powers the wall socket?

Now let's assume that the light is plugged in and the wall switch is turned on, do you...

Go back and flick the switch a couple hundred more times, or...
Jiggle the power cord in the wall socket, and then flick the switch another dozen times, or...
Do you unscrew the bulb and replace it with a new bulb and then try it?

Well, you get the idea -- troubleshooting electronics is no different. There's a logical progression of things to check, and you'll be surprized how many times the solution turns out to be "a cable wasn't plugged in."

Lesson #1 is Check for Power. And this means starting at the power source and checking the obvious:

Is it a good power cord? (i.e. does it work somewhere else/check continuity of the wires/plugs in the cable)
Is it plugged into a good outlet? (are other things plugged into the same outlet and do they work?)
Is the power to the outlet turned on? (sometimes a circuit breaker has been triggered off)
Is the power cord plugged into the device? (Sometimes these wiggle loose.)
Is the power switch on the device turned on? (Not all devices have switches)
Do any power lights come on that normally come on? (Caution -- power lights can burn out, so they're not always right!)
Does the device use a fuse? If yes, unplug the device first and then check the fuse to make sure it has continuity from one end to the other. (Glass fuses are usually easy to see if the wire is burned out inside.)
With your DVM (digital volt meter) or DMM (digital multi meter) or VOM (volt-ohm meter) and the device plugged in, is the reading of the voltage at the device's power input connections what it should be? (Caution: if testing 120VAC remember this is dangerous electrical current - great care is necessary!)
If it's a battery-powered device, are the batteries good or are they weak or dead? (Your DVM will tell you!)
Until you are comfortable with poking around inside an electronic device with meter leads and know what to touch and what NOT to touch, don't just "touch stuff to try them out," especially if you're working with 120vac (or 240volt) current.

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That's it for now. I hope the next poster will perhaps add some information about the kind of equipment you can buy or make and that you should have for testing power, with the thought in mind of keeping it simple and inexpensive.

jklingert
02-23-2013, 02:48 PM
First of all, be safe. Never plug anything into power until you've thoroughly checked your work.

One of the most important tools to protect yourself and others is to add a GFCI outlet to your workbench area. Home Depot and other places sell ones like this (http://www.homedepot.com/buy/tower-manufacturing-corporation-3-wire-gfci-outlet-adapter-30339005.html) that are portable and plug into an existing outlet.
18296

I hope the next poster will perhaps add some information about the kind of equipment you can buy or make and that you should have for testing power, with the thought in mind of keeping it simple and inexpensive.
A simple nightlight from the dollar store is a cheap tool to plug into power cord to test AC power.

LightUp
02-23-2013, 03:52 PM
I like the "think logically" part.
Around my place logic thinking is; "Dad, please look at the TV. It won't change channels and we changed the batteries in the remote, but ..." Thus far it goes.

howards9
02-23-2013, 08:25 PM
Typical troubleshooting checks:
1. Power
2. Connections
3. "Only an idiot would do that" (I'm perfect and wouldnt do that) things
4. Check and recheck and check again steps 1, 2, and 3.
5. Step back, take a break or work on something else for awhile and then check 1, 2, and 3 again.

beeiilll
02-23-2013, 08:41 PM
Well lets see what I can think of to add here.

You should have a good neat workplace to work on projects, not just a dining room table or a coffee table in front of the TV. A good 3 foot deep workbench that is at a height off the floor that is comfortable for you to work at. Also having your tools handy and organized lets you concentrate on the project not where did I leave some tool.

A good stool to sit at your bench if you intend to spend much time there.

Good lighting will help you work in comfort and get less fatiqued. I use 4 foot overhead flourscent lights as well as a magnifying lamp on an articulated arm to help me look over things like solder joints or small parts for problems.

If you are going to solder, a good exhaust fan is necessary to remove the fumes away from you.

A small music system can help relieve stress when you get something that doesn't work right as it will help calm you and you can also take a break once every little while and get up and away from the work for a bit. Taking breaks at regular intervals will help you with the job as you will be more likely to be relaxed and find that working on things is more enjoyable.

Spend a little more and buy good quality tools for your workplace. Nothing is more frustrating than having a cheap screwdriver slip and scratch up a nice new project. Good tools also take less effort to use and work better.

A good work mat on the floor if you stand will reduce leg fatique and make it more comfortable for you as well.

Practice at various things will help improve your skills at things such as soldering, bending leads for inserting components into boards, cleaning flux off solder joints, etc..

I actually have a small fridge next to my workbench in my basement since I spend a lot of time there. I can get a cold drink whenever I need a break or keep a pack of cookies in there as well for a snack.

You can get reference charts of many things depending on what you are working on to hang around for easy lookup if you need information for your projects.

Always keep a pair of safety glasses or googles and some ear protectors or ear plugs around your work area. It is easy to not use them but you can't replace an eye just because you didn't want to take an extra few seconds to find some glasses. If you think safe it becomes second nature to use the things and you won't even think about them after awhile, you will just use them. But you need to ingrain yourself with the use of safety items for a bit to make it "stick".

A problem that I have seen new people make often is to try too hard to finish things in one sitting and then get frustrated when they break something because they were tired or pushing too hard. Take time to do things and think ahead a little. You will save yourself from frustrations and problems in the long run. Believe in the motto: There is always tomorrow to finish something.

That is enough for this post. I will think about the troubleshooting tips and post more later.

mkozik1
02-24-2013, 01:42 AM
Couple of other adds: 1) Good anti-static band. Nothing like getting up to stretch, sitting back down, grab your work and zap a chip!!! 2) Have a PC on or very near you bench for reference use. Nothing like multiple trips upstairs to do research!! Obviously this will come later once all is built, but ....

LightUp
02-24-2013, 10:16 AM
A small assortment of test leads will little grabbers on each end, so that you can clip a test lead to the circuit without worrying about the probe slipping off and short circuiting something- causing more unnecessary troubleshooting. This also helps when checking higher voltages and you want to be free from touching the chassis. I usually turn the power off first clip on to the circuit I want to measure and then turn on the power and see what happens, either meter or oscilloscope.

Watch where all your cords, test leads, etc are so that if you move your chair or your body, or your equipment that you do not drag/rip the probes off the cicrcuit with the power on. This can also happen while reaching for a ringing phone nearby and accidently jar the equipment.

blantrip
02-24-2013, 02:23 PM
Great thread.

SAFETY is number one. Safety is usually just common sense, but here are some safety tips:

1) Verify a circuit is dead before working on it by using Check, Test, Check - Check your multimeter (or whatever you are using to check for voltage, i.e. night light voltage tester, etc.) on a known working source, test the outlet you are verifying, then check your test device again on a known source. If you are just "trusting" that your test device is operational you could be in for a surprise when you touch a live circuit you thought was dead. Multimeter fuses can blow if it is selected to read amps. light bulbs can burn out at any time, when you connect it to your circuit you are testing and you won't know unless you test again to a known live circuit.

2) Never use electrical equipment or tools near wet areas. Tough to do with Christmas lights, but make sure you are using GFCI outlets or extension cords.

3) Ladders - Be safe, 3-points of contact at all times, don't stand on the top rung, and watch overhead power lines.

4) 18307 A network cable tester was one of my best investments and it was one of my least expensive.

5) A magnifying glass, especially with a built in light is another great tool.

6) Troubleshoot logically. Easier said than done maybe, but start at the top and work down from there.

7) Ask questions.

jpb
02-26-2013, 05:43 AM
Typical troubleshooting checks:
1. Power
2. Connections
3. "Only an idiot would do that" (I'm perfect and wouldnt do that) things
4. Check and recheck and check again steps 1, 2, and 3.
5. Step back, take a break or work on something else for awhile and then check 1, 2, and 3 again.

I heartily agree with this, especially points 3 and 5. I am technician by trade and do things like this on a regular basis.

And as Dirk said, think logically, flicking the switch 100 times is probably not going to accomplish anything.

Jon

CaptKirk
02-26-2013, 02:28 PM
Check for correct part orientation. Some parts, like resistors and ceramic caps do not have a polarity, but most DO have a specific orientation like electrolytic caps, diodes, ICs, LEDs, etc.

On boards with sockets for the ICs, check for proper power to the chips BEFORE putting them in. This is especially true for boards with the transformer and rectifier circuits built in. For boards that use an external power source, make sure DC power is connected with the correct polarity.

If you need to rework, traces and solder pads do NOT like excessive heat- you can lift pads and traces and either ruin a board, or require tedious rework to make work again (blue wires) so be judicious with the heat. A "solder sucker" is a must- a rework station is better but can be pricey but save time and boards.

Johnfish211
02-26-2013, 03:13 PM
I worked with a Russian engineer early in my career. (Late 80s) He had a great deal of wisdom and I learned a lot from him. When trouble shooting circuits for him he would always tell me "Make one mistake at a time!"

It took me a little while to figure out what he meant. In essence if you are troubleshooting only change one thing at a time. Then retest. It is very easy to introduce more problems if you change a lot of things at once.

John

jlowe
02-26-2013, 03:32 PM
I worked with a Russian engineer early in my career. (Late 80s) He had a great deal of wisdom and I learned a lot from him. When trouble shooting circuits for him he would always tell me "Make one mistake at a time!"

It took me a little while to figure out what he meant. In essence if you are troubleshooting only change one thing at a time. Then retest. It is very easy to introduce more problems if you change a lot of things at once.

John

Lots of great advice here, and some that applies to more than electronics. This has always been my go-to trouble-shooting methodology. It's much easier to figure out what's wrong when you know at what step problems appear. But I've never heard it summed up so succinctly as "make one mistake at a time!" I really like that.


Another one is RTFM. Read as much documentation as you can ahead of time. Search for the board you are building on the forums and learn what others have learned through their experiences. Chances are, someone has already experienced the same issue.

Capt mentioned something along this already, but... If you solder your LEDs backwards, your board might be working fine but can't show you a status LED. Plug in lights and test for that. (I made this mistake!)

kingofkya
02-26-2013, 03:43 PM
Capt mentioned something along this already, but... If you solder your LEDs backwards, your board might be working fine but can't show you a status LED. Plug in lights and test for that. (I made this mistake!)

Multmeters have an handy diode tester witch will light up leds fyi. Very important with smd stuff as you don't want to get the led s back words.

CaptKirk
02-26-2013, 04:07 PM
Multmeters have an handy diode tester witch will light up leds fyi. Very important with smd stuff as you don't want to get the led s back words.

Thank you - I just learned something that I had never thought about before...