How to check my soldering using a multimeter

[Maurice Krijtenberg]

Hi guys,

I'm struggling a bit with building my first battery powered sensor. I have the following setup:

• Rev.8 of the newbie/easy pcb board
• Chinese clone Arduino Pro Mini 3.3v / 8 MHz
• NRF24L01+ radio
• 0.8-3.3 V DC 3.3 V StepUP Boost

I have no sensor attached as of yet, because I get stuck at init. I get a "RADIO:FAIL"

My first thought is: maybe I've done some bad soldering. So my question is: how do I check if all connections are okay, with a multimeter? I have no experience with electronics and soldering, and the multimeter looks like a Star Trek gadget to me :)

Second question: When I'm using the serial monitor in the Arduino IDE, the Pro Mini gets powered by both my USB connection and the battery (I need it on, because it powers the radio). Is that setup okay? Or is there another way to monitor the debug messages?

[sundberg84]

@Maurice-Krijtenberg .

1. Check the voltage (DC) on the radio from VCC to GND. It should be the same voltage as you have on the batteries (from GND to PWR on the blue block). Check this link (https://www.google.se/search?q=dc+voltage&source=lnms&tbm=isch&sa=X&ved=0ahUKEwitnp6B8bnRAhXClSwKHSA1B30Q_AUICCgB&biw=1143&bih=702#imgrc=9AY0NGzZHkizoM%3A) for the symbol for DC voltage and how to set your multimeter.

2. No, that is not correct. Using the serial monitor you connect RX/TX and reset(dtr) only. Power should come from the battery only and this can be whats causing your problems in 1). The radio is always powered directly from the batteries to avoid noice (pcb is designed so if you have BAT jumper shorted).

3. You also need a capacitor on the Radio!

[Maurice Krijtenberg]

Thanks for the fast reply @sundberg84

I didn't know the capacitor was mandatory, but I've added one.

Before I start measuring using the multimeter, I want to make sure 2) is correct. I removed the VCC/GND connection and only left the RX/TX connected (I don't have reset), but now I don't get any feedback in the monitor at all. I know my PL2303HX isn't the best USB/serial device, but it's the only I have at the moment.

[sundberg84]

@Maurice-Krijtenberg - ok, the try adding ground as well - but dont add VCC from your USB device.

Did you check the voltage levels? If you dont get anything it can indicate your arduino isnt getting enought power since you got it worked adding VCC from USB. Check voltage levels on the arduino as well VCC - GND. Might be a solder problem or a booster problem (Arudino is powered throught he booster).

Soldering is an art - but if i check your pictures I would make sure that the solder is touching the pads/holes so you get a good connection. If you look at A2 in your picture this isnt good enough to make a ok connection. The solder should "sink" into the hole in the arduino.

[scalz]

Hi.

If you want to check your voltage levels, continuity etc, learn how to use your multimeter :
https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter/all

VCC between your ftdi and your board can be removed if you power from battery depending on your circuit (follow @sundberg84 advice for this), but the GND connection is in all case mandatory or it won't work, get garbage etc.. ;)

[Maurice Krijtenberg]

Again: thanks for the fast replies. Don't guys to work or something? :P

1. Connecting the GND to the FTDI made my monitor work again
2. Using the multimeter I see the radio gets 3.3 V, so I guess the problem is somewhere in the data pins.
3. @scalz Thanks for the link! I was looking for something like that. I'm gonna read it and I'll return with some questions, or answers ;)

[sundberg84]

@Maurice-Krijtenberg - With that info - your conclusion is most likely true. If you are getting a good voltage but Radio Init fail - recheck every data cable connection and solderpoint.

[Maurice Krijtenberg]

Finally!! I got it to work :)

Using "Continuity mode" on my multimeter, I found out that two connections didn't work. I probably damaged my board during soldering. Using two wires I was able to get it working

One step closer! Thanks again @sundberg84 and @scalz

[sundberg84]

@Maurice-Krijtenberg - nice to see! Great work.
This is why its so dangerous... you get that rush when you fix something and you need more and more... its like a drug :)
Thanks for reporting back!

[Nca78]

Hello, now you have read how to use your multimeter, may I suggest you check more tutorials from Spzrkfun website ? I think they have one about basics of soldering that you should watch ;)
Looking at the "balls" of solder on the pins of your Arduino you skipped that step which is crucial to have good working circuits.
And don't forget to always keep your soldering tip shiny !

[Maurice Krijtenberg]

Hey @Nca78
Thanks for the suggestion... I just watched this video from sparkfun: https://www.youtube.com/watch?v=f95i88OSWB4
Wow.... I was doing it soooo wrong haha. I'm gonna practice a bit to get my "balls" look more like "volcanos" (yes, still talking about electronics :P )

[tbowmo]

@Maurice-Krijtenberg

First time I've seen a person using safety goggles when soldering, and I've been in the industry since early 90's.. Working in a handful different factories.

[Yveaux]

@tbowmo You don't want a hot soldering iron to bounce back into your remaining eye! :confounded:

[Maurice Krijtenberg]

haha :joy: well, to be extra careful, I wear gloves during soldering.

[tbowmo]

Another thing I noticed in that video..

"Some has a heating element in the handle, this one has it separate" So the heating element is in the blue box?? And heat is transmitted through the wire to the handle? Won't you burn your pretty hands, if the heating element was in that blue box, Wonder how hot that cable would be, to heat the soldering iron part to 300 degrees celcius..

Why don't they make those tutorials factual correct?

[hek]

Reminds me of this (disturbing) video...

https://www.youtube.com/watch?v=5QajKC_EyXI

[mfalkvidd]

http://makezine.com/2016/03/08/beautiful-woman-soldering-stock-photo-wrong/