Tech Tips: Replacing Through-Hole Components | SRA Solder

In this tech tips video, Sam takes us through his process of replacing electrolytic capacitors on one of the 12 tone generator boards in 1960s Farfisa combo organ. All of these tips and tricks apply to any through-hole soldering projects.
01:06 - Step 1 - Tinning
02:37 - Step 2 - Desoldering
03:45 - Trick #1 - Bent leads
07:35 - Trick #2 - Cut the leads
08:29 - Step 3 - Lead Forming
10:23 - Step 4 - Placing components
10:35 - Trick #3 - Tacking
12:52 - Step 5 - Soldering
13:43 - Step 6 - Trim the leads
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For more information on how the tone generator cards work:
www.bustedgear.com/repair_Farf...

[@billlaut608]

Nice video, Sam! Reminded me of when I replaced the caps in my 1970s amateur-radio slow-scan TV monitor and camera. My Aoyue 8800 went through its paces and did such a thorough job that the desoldered parts fell off the boards!
For soldering the replacement parts, I found using a chisel tip best. A tip of solder to form the heat bridge, then touch the pad and lead and finish soldering the joint.
Those boards look like candidates for your ultrasonic cleaner!

[@samuelglennmusic2174]

Yeah these boards definitely need a good cleaning! Canned air didn't quite cut it.

[@billlaut608]

Here's a suggestion for a couple of future videos.
#1 - A demonstration of the Aoyue 8800 Desoldering Gun. Maybe show off how thoroughly it removes the solder from through-hole joints. And how to minimize it getting plugged with solder, requiring a boring with the drill bit.
#2 - How to replace the heating element. You've already demoed replacing the 500W heater in hot-air, and maybe (I think) replacing the element in the soldering iron. Now, how do we replace the element in an 8800?

[@redberlingo]

Great video... can you add any details re the temperatures you find best for this sort of work...

[@SRASolderLab]

Hi and thank you! I personally work at 350 C / 662 F with my setup. This seems to be a good point for vintage PCBs and fairly robust through-hole components like this when using leaded solder. For smaller boards that are more sensitive you may want to start lower around 300 C and if you find 300-350 isn't hot enough to efficiently heat the joint then you could go up to 400 C / 750 F. That's about the top of the range I would go. Any further and it gets too hot and oxidizes the tip rapidly. The one exception would be soldering chassis grounds when you're dealing with the surface area of the chassis in which case a bigger tip/higher wattage is necessary. Also, on heat sensitive components like LEDs and diodes, I'd use forceps or an alligator clip to absorb some of the extra heat. There are several factors here to consider that affect heat transfer from your iron to the workpiece. Including the surface area you're heating, the surface area of the tip, the condition of those surfaces, the iron wattage, the temp of the iron, melting point of the solder, and amount of flux used. I used 63/37 rosin core solder wire in 0.031" diameter with a 60W microprocessor controlled iron. By tinning the pad and the iron and using the broad side of the conical tip, I was able to get perfectly adequate heat transfer.

[@redberlingo]

@@SRASolderLab Great answer - thanks!