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Working on LoRa project with the RFM95W. Most online resources like 1 and 2 suggest using a PCB since the module itself is quite small and hard to work with; but where's the fun (and learning) in that!

After soldering it looks like: (it isn't meant to be deployed, just testing it out on my workbench at the moment)

Please see photos:

Front Side

And the back side:

Back Side

To my untrained eye, they don't look like they would cause a short.

Googling brings up continuity testing, which would be proving the negative (no continuity means no shorting) but I am wondering if there's something better and what the procedure is like?

I do have this Multimeter.

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  • \$\begingroup\$ is the board actually have a short? or you want to double check whether you have created a short accidentally \$\endgroup\$ – Umar Jun 24 '18 at 16:56
  • \$\begingroup\$ @Umar I want to check whether I have created a short accidentally \$\endgroup\$ – Sam Hammamy Jun 24 '18 at 16:57
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    \$\begingroup\$ If you need to solder small parts, you might want to consider using a magnifying glass or a magnifying visor. The connection to SCK has a loose strand which might cause a short if that wire was twisted a bit. \$\endgroup\$ – Andrew Morton Jun 24 '18 at 17:35
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    \$\begingroup\$ I find that a 20x or 10x optical 👁 lens to the eye gives the best feedback for potential shorts. The other is ESD prevention and a DMM \$\endgroup\$ – Sunnyskyguy EE75 Jun 24 '18 at 19:17
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  1. Clean the board with flux and let it shine
  2. use a good magnifying lens to visually check if there are any shorts, especially between two pins of the module
  3. Measure power supply pins with respect to ground to make sure there is no short waiting for first power on
  4. check the assembly BOM again once more to see that all the components required to be mounted are indeed mounted (and also, components that are not supposed to be mounted are left open)
  5. measure resistance values (you should be able to read approximately actual values, but not for all cases), at least they should not just read zero or Very less ohms..
  6. Multimeter is your friend. Check neighbor IC pins one by one. Pin4 can be short with pin 5 or pin 3.. so, that can be performed for all the pins.
  7. Check for diode polarity and capacitor polarity (if any)
  8. Repeat the same test for the connectors
  9. power on the board with current limited power supply
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An addition to the suggestions above : don't use the meter on "beep" and just listen. Put it on ohms and actually look at it for each measurement. On a board like this you will see all kinds of resistances (even negative when a cap has some charge on it, in this case the reading will take a while to stabilise), so you are looking for anything suspiciously low. But when you do a cable (where you do every pin to every other pin) any resistance that is not infinity is a sign something is not quite right. (It's rare but once in a while you see shorts that actually have significant numbers of ohms.)

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First, select resistance or continuity on the switch on the front of the meter and make sure that there are no shorts between adjacent wires in the ribbon cable. You will know it is a short when the continuity indicator bleeps or the resistance measurement shows zero or a very low ohm reading (less than 10 ohms).

Next, plug the cable into your Raspberry Pi with the ribbon running away from the board and the polarizing bump pointing into the board. Do not power up your Raspberry Pi yet. Next measure the voltage between the ground and the two 3V3 connections in turn. Again, you should see a value very close to 3V3. If these checks fail, shut down the Raspberry Pi disconnect the cable and check all your wiring.

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