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Beginners tips /help please

Hi everyone, I'm really interested in repairing electronics. It started off by replacing screens on phones and repairing consoles etc. I'm still learning but I'd say I have quite a good knowledge of electronics now.

I would just like to know how to troubleshoot a phone/electronics

For example, it doesn't turn on.. Tried a replacement battery still no luck, it's not the lcd. What steps would you pro's take next? Can you tell me how you would test the smd caps or how to tell if the phone is getting power etc.

Thanks everyone in advance.

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Hi John,

As a primarily self/internet taught electronics repair person, here would be how I would approach this. Assuming you are a beginner to this and don't have a lot of tech toys to troubleshoot this we will only use a multimeter (available for $5-$70 depending on how many bells and whistles you want, this one for $6.40 on amazonshould work perfectly fine). for a description on why you want a multimeter/why it is useful, see footnote 1.

I will also assume that we don't have a schematic of the device in question because lets face it, most of the time you don't.

Lets take your scenario, in which a customer (friend) tells you their device (a smartphone for example) doesn't turn on.

first try to ask them what they think happened. If this is a device that doesn't turn on randomly, or if it was acting odd (i.e. erratic performance, not attributable to a single point of failure) before it stopped working, then odds are it is water damage, (to treat this look at footnote 2.)

If it doesnt sound like water damage and you don't see any when you open it up, then start double checking the device yourself. The rule of thumb when repairing something that isn't yours is: Unless you saw it happen, what they said happened is just their perspective, and should be checked again by you. (there are so many times that I haven't double checked what a customer said and that turned out to be what was wrong that it should be a rule.)

Lets go over what we know:

It doesn't turn on, (also, no signs of water damage)

since electronics run on electricity (I know this is rudimentary, but bare with me) trace the electricity.

all electronics have a closed circuit, so you can follow the circuit and check to see where there is a connection.

If it has an internal power source, check the battery with your multimeter. What should the voltage be at? (google nominal voltage) If it is charged (as determined by voltage readouts), trace farther up. If it doesn't have power, check the charger, if yes then plug it in and check the battery, does the battery get a charge? if no then there is a problem is between the battery and the charger, check intermediary points on the connection when the usb cable is plugged in, as soon as you find a point where the voltage picks up again, you have just narrowed your search. if this is a circuit board, check for any cracks in the solder that could be causing a faulty connection.

Note, just because you find and fix one problem, that doesn't mean it will suddenly work again, there could be a few problems with a device, normally a root cause which in some cases caused a problem, which caused another problem, which caused another problem... you get the idea.

I hope this helps you further your technical fixing skills!

Footnotes:

1. A Multimeter is useful for many diagnostic reasons, but for the basics, you care about four things.

a: Whether two points are connected (by checking resistance, if the loop closes it will display the resistance on the loop, if there is no resistance it will show a 0 or beep. If there is no connection the screen will also tell you that. This is useful because it helps you trace your way through a circuit board via trial and error). This is also how you would check if a resistor is blown.

b: the voltage between two points, (allows you to check battery charge levels, as well as voltage drops in a circuit.) (in case you are new to electricity, a basic analogy of voltage is the pressure of water in a pipe)

c: The amperage between two points (going back to the water analogy, Amperage is equivalent the flow rate of water), this is helpful for determining the amount of drain being experienced by a power source i.e. battery).

2 if a device is exhibiting symptoms of water damage the first step should be opening the device up to just double check that there isn't water still in it, shorting something out. Open it up, if water is there disconnect all power sources (including battery if possible), next remove the water, (an optional step here is to pour 97% isopropyl alcohol in the device (but try not to pour on a screen, it can mess with adhesives) the benefit of this is the alcohol will often displace the water, meaning you now have a device that is now soaked in alcohol, still not ideal but way better because alcohol evaporates faster than water and is less corrosive)this can be accomplished by drying with a hair dryer (not on high), next put in a bag with some dessicants (those little bags in food that say do not eat, can be purchased on amazon for cheap) for a day or two, reassemble and voila!

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Thank you very much, was a good read and helped me out a lot!

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Your welcome John, I'm glad you found it helpful.

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@lost815execute besides all those great answers you already got, I swear by the right schematics and board layouts. It does not matter what make and model your phone is, unless you know what part you are looking at, it will be difficult to just replace. You can not distinguish if it is a capacitors, resistor, inductor etc. simply by looking at it. Same goes for troubleshooting. You do need to identify the individual circuits responsible for i.e. power up etc. Of course you do need the right tools. Multimeter, capacitance tester, etc. I use some ST5S smart tweezers to help me with the identification of the SMD components.

Update (02/05/2017)

As you commented to @theimedic if it is just an example about how to check a no power on situation, there are no standard answers. These are all model specific. Use a Samsung Wave schematic for example

Block Image

and you'll see that is will only work for this model. You cannot use it for any other phone. There are not really any commonalities between cellphones on a circuitry level.

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Thanks for the good info, a couple of questions if you don't mind, is there a good website for schematics? I've heard of zxw but as this is more of a hobby I'd rather not have to pay for a dongle. And say I done a visual check of the pcb and there was a suspicious capacitor, how would I check to be sure?

Thanks

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@lost815execute you really can't check that component unless you know what it is. Again, you'll need both the schematic and board layout. You can of course also ask on here. Post a Question and add images of where the component is located. Use this guide for those questions Adding images to an existing question ZXW is great, I personal;ly use PADS which is similar. I hear you about the hobby, but there are not really any alternatives. Same with schematic websites, not any one that is better than any other. Most of the schematics will even cost some money. Tools, schematics, etc all make this a costly hobby

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I understand what your saying, thanks for your help. The main thing I was wondering is that if it says check this *insert here* and make sure it's *insert here* how would I check that? With a multimeter set to voltage? Would I need the phone to be connected to a external power supply whilst doing so? Like I say I'm still a beginner so any help is appreciated

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@lost815execute you would not need power on to test a single component. For that you need your multimeter and measure the part. This is where it once more gets interesting. If you do not know what you got, you can't measure it. Resistor? Capacitor? Inductor? Fuse? Who knows....Now there are ways of troubleshooting for short circuits as well as components that have failed but once more you need to have a schematic and need to know which component is located where. It might help if you can give us a specific make and model with a specific error. We could try and be very specific on that. @rany @refectio would be a great resource for anything iPhone boardlevel related. Of course there are more specialist than those two on here, but they are the first once coming to mind.

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@oldturkey03 I worked on a really well researched answer, with links and everything and when I posted it, the system said it was spam and then it was gone...just like that.

I didn't feel like spending another 10 minutes to re-write it.

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Ok. First could you tell us which device you're working on. After that, since you already tested the battery, and have ruled that out. You'll want to test the charging port, is it getting electricity? After that you'll need to find the chip, on the board, that is responsible for charging. That last part is no easy task. I've currently put $800 into my microsoldering equipment, and find half of it lacking, and waiting to reinvest

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Hi I'm not working on any device in particular I was just using that as an example. Was more to do with how would I test the charging port is getting power and how would I test if that power is going further through the board if you get what I mean

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Well as I'm certain you've figured out, each phone is very different, so you kinda literally have to go through a case by case process. Which make? Which model? If you have any questions we're all here to help. And as you learn and grow, we'd love to have another tech here helping with us. The worlds a big place, gots lots of problems need fixin

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@lost815execute , John , Other then the vast info. on the net in repairing electronics, I would suggest try to get part time/full time job at a good electronics repair shop that interests you. There hopefully you will gain knowledge looking over the shoulder of a master Tech., who may see your interest and can share his knowledge, technique, specialty tools, etc.. Another way possibly is to gain knowledge through on line or in class training courses as seen in links below, which you can do a search on for your preferences. Good luck.

I hope this helped you out, if so let me know by pressing the helpful button.

https://mengtormdtraining.com/?gclid=CL3...

http://cellphonerepairtraining.ca/

https://online-tech-training.com/gb/et_v...

http://study.com/electronics_repair_trai...

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My take on this is that microsoldering repair is about:

- Knowledge and experience in troubleshooting. For this you need a DMM, brains, google, schematics, and some tears. Start with basic components (what are resistors, caps, filters, diodes, etc.). Move to circuits like backlight circuit, touch circuit, etc.

- Microsoldering tools. The cheap ones are the Japanese Hakko. Cheaper will introduce more variables.

- The skill to use the tools. Be able to replace small components and micro BGAs. Lots of frustration.

- Parts.

What does it matter if you have everything you need except one of the above? I know I need a 2.2K pull-up resistor because my brains and my $150 DMM and my schematics told me so. I can see it looks bad through my $700 scope. I have the tools and skills to replace it. But I don't have a replacement. That part is like $0.01 and yet my phone will not boot without it.

Or I have it, but am not skillful enough to replace it and instead heat the board too much and kill it.

All the above mean serious investment in time and money. Just that you know what you're up against.

Many have done it.. it is far from impossible, but it does take dedication like everything else you want to learn in life and be good at.

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I'm far from a professional repairman, and my knowledge of tech repair is probably less than 1% of the Greybeards like @oldturkey03 and @mayer, but as one enthusiast to another, I like the challenge of finding stuff out and figuring what's wrong. For example, if I had a phone that didn't power on (maybe a galaxy note 3), I would check for water damage, fried components, research on the internets to find error codes, anything at all. What many people don't realize is what they would do without the internet. Remember this: FIGURE IT OUT! What if there where no repair shops, internet, people that know how to do it? And know for some good advice that totally counterdicts that last sentence: You can always rely on us folks at ifixit to give you a wealth of repair answers, and we can fix. We can fix it, ba, ba bum, bum bum ba bum! (We are farmers/We can fix it, get it?)

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John will be eternally grateful.
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