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Super super basic question
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Super super basic question
Multi Grooves
I'm attempting to build a Zlob VCA but have a question about soldering:

In this diagram it looks like the resistor has been soldered top side of the board:

**Edit** the images aren't my board/build, they're lifted from the manufacturer's guide**

Is it just solder that leaked through from the underside or am I missing something?

Here's a view of the underside which looks like I'd expect- everything has been soldered:

What is the deal?
Multi Grooves wrote:

Is it just solder that leaked through from the underside or am I missing something?

I'm not 100% sure, but I think this is one possible style of cold solder joint, where you may have been heating up the leg of the resistor, but not the pad so that the solder was just pulled through the hole (capillary action?). I would wick that ball up and redo the joint, taking care to heat the resistor leg *and* the pad when you solder.
It's fine and pretty normal.
The solder tends to "wick" up any hot metal parts. This is pretty common. Not a problem. (Maybe using a bit too much solder, but thats it.)
Also, not sure if this was your board or not - but it's possible that it was soldered from the other side. I sometimes do that if there is a particular reason. The electrical currents don't care. hihi
Multi Grooves
The images shown are the build guide offered by the manufacturer. It seemed weird that there was solder on the top of the board on one of the legs but looking at how the resistor sits, its clear that it'd be the only side soldered (not the fat resistor end).
tassie tiger
I stumbled upon this question in the Eurorack forum, and provided my two pennies worth there.
Ideally the solder flows thru the hole and fills it completely, showing also on the other side, so the joint is solid and reliable. This looks like just a bit too much of the solder was applied, so it creates this ball on the other side. As long as the soldering side joint looks good it is not a problem. Soldering the leg from the top side is also doable, doesnt really matter.
So long as there is a good connection on the solder side of the board, the design of the pcb should make it somewhat irrelevant (from a connectivity point of view) as to what happens on the other side, but, as has been mentioned, its more common than not for the solder to flow through the hole.

In the old days things like vias (linking holes) may not have been plated through, and would have had to have been filled, but now everything has through hole plating (there are, undoubtedly exceptions, i know)

The important thing is the flow on the solder side. A nice meniscus arround the lead of the component shows good flow. Beading on the solder side should poor flow and probable poor connectivity / poor structural integrity.
Only thing is that if you have such big blops of solder on the other side it implies that the soldering iron was fairly long on the solder point heating that much of solder and also bigger solder blops tend to need more time to cool down. Some heat sensitive parts wouldn't like that... Resistors are mostly okay with this but some caps, IC's or trannies could take damage.
Multi Grooves
Thank you, everyone.
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