/diy/ - Do It Yourself

[Anonymous No.1645662]

I'm looking for help on improving this flowchart.

The backstory is that I was browsing /diy/ earlier today, and I saw this thread where someone was trying to fix a speaker of some sort. It was clear that this anon was a total beginner (not much troubleshooting skills, didn't own a multimeter, etc). He was trying to replace some old electrolytic caps that were clearly bad, but wasn't sure why it still wasn't working.

Anyway, several anons jump in with suggestions like: reflow the entire board in your oven, remove every cap and measure it and resolder it, purchase a several hundred dollars piece of test equiptment to measure capacitance in circuit, etc.

So I'm sitting there noticing that no one has stated the obvious yet. Things like is it plugged in? Is the fuse blown? You know, all of the extremely fast, simple, and free stuff to check first. Instead, all these anons were giving instructions on how to do a deep analysis of the circuitry without even asking for a pic of the OPs solder job. They just weren't picking up on the fact that OP was a noob, and was looking for basic advice. It erks me because people that want to show off how they're all (t. electronics expert) don't even know the basics of troubleshooting. Instead of starting with the simplest, non-destructive things, they reveal how little they know by recommending something stupid difficult (to a beginner) AND destructive.

That shit happens all the time around here, so I wanted to make a flow chart to just get the basics out of the way. Just a picture that you can reply to the OP with, saying ---did you check all this stuff FIRST?---

So I sat down and spent the last 20 minutes throwing this flowchart together in PowerPoint, but I can't spend too long on it, so I'm wondering if any other anons have suggestions, contributions, or can point out things I missed.

[Anonymous No.1645663]

>>1645662
I'd be happy to incorporate any input and re-draw it later. Hell, even redraw it yourself if you have the time and the motivation. All I want is a goto picture that describes the beginning of the troubleshooting process, before another OP, who is totally a beginner and looking for beginner advice, gets carried away with buying an ESR meter before checking to see if the fuse is blown.

I'm hoping to see the finished flowchart as the OP on the ohm thread eventually, or whatever, but I would be happy with just a concise troubleshooting flowchart that I can post on some of the simple 'help me fix this thing' threads.

Thanks!

[Anonymous No.1645671]

>>1645662
>I have a problem with some electronics device
>OK
>Is it actually supposed to do the thing that you think is a problem?
>YES
>Problem Solved!
Delete your post

[Anonymous No.1645725]

>>1645671
That's very brave of you to put yourself out there like that with such an articulate and honest opinion. I bet you're one of those guys that does super great at group work assignments at your high school.

[Anonymous No.1645949]

>>1645662
Amateur/10

If it's blowing the fuse, let's say for a 120v device, a common trick is to take an incandescent bulb, around the wattage of the device when the draw is quiecent, and wire it in series with the mains. The brightness of the bulb will indicate the current and pinch the voltage to the device is there was a fault. Bright bulb, high current draw, fault is there. Dim bulb, low current, fault is gone. From here, the tech starts isolating portions until the fault is removed. The bulb stops current from destroying the unit even more, especially after components have been replaced and something is wrong.

Checking caps is great, even squeezing them can show that their faulty with a scope. On audio circuits a wet finger is your best friend. There's alot more to troubleshooting electronics than just caps and smells. Furthermore it would probably be wise to identify the type of component or equipment first (pwm? Class a amp? Brute force Ps? Bjt current source? Mos current source? ) then laying out a strategy. In the case of your plus/minus ohm check, it doesn't make sense if those leads came from a rectifier with a smoothing bank.

I feel this is a wonderful endeavour and if this shitty board would have stickies (which they never will cause its 4chan and chink moot is cheap af) the info could be quite valuable in the spirit of diy. But to do it right I think you have to break out troubleshooting basic components, common practices for set components, configurations and then start the decision tree for that. Course if you do, save that shit, post it somewhere else, where it can be kept and referenced. Just my 2 satoshis.

[Anonymous No.1645961]

>>1645725
I read it wrong at first as well dude, chill out.

[Anonymous No.1645989]

I love how easy it is to spot someone who doesn't know their shit because without testing anything the first assumption is almost always
>caps are bad

Capacitor plague is long over and in my experience it's pretty rare that caps, including electrolytics, are sources of failure in most electronics these days.

Typically in most of the circuits I'm working on I find it's simple semiconductors like diodes and discrete transistors that fail. In switched mode power supplies in particular it's typically transformers and the output rectifier diode. In many cases it's a cascading failure where one component failing took out loads of other stuff down the signal path.

Of course there's no gospel for how things will failure. There's all sorts of reasons things die: transient voltage spikes or ESD, user incompetence (reverse polarity, wrong voltages, etc.), defective components, poor solder quality, bad circuit design, ant took a leak on your board and shorted two traces, etc. Anyone competent should be able to narrow down the cause of failure starting with the most likely failure mode for a given device and working heuristically towards the root cause.

[Anonymous No.1646117]

bump for thread visibilty
u
m
p

[Anonymous No.1647023]

>>1645662
Apart from the first decision box being wrong, you mean?

[Anonymous No.1648316]

Sounds like we need a general decision tree for the absolute first step, then maybe a different tree for each of the main topics after that (power supplies, audio circuit, digital circuit, auto, motor, etc).

[Anonymous No.1648383]

>>1645989
>Capacitor plague is long over
There are still shit factories pumping out less than high quality caps in chingchong land, and there are still chingchong engineers making super cheap junk with underrated components. Electrolytics, while not necessarily the goto theres-yer-problem component anymore, should still be examined/tested.