Questionable solder joints?

jamiet · 2216

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Offline jamiet

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on: May 04, 2014, 01:51:41 PM
This is my first electronics project and I've been feeling a bit nervous about cold solder joints after reading so much about them. I thought I'd attach some pictures to get some opinions before I proceed much further.

I am using a Hakko 936 with a roughly 2 mm chisel tip set to 750 F. Solder is Kester 44.

Thanks!

-Jamie.


Offline kgoss

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Reply #1 on: May 04, 2014, 03:15:42 PM
I like to do a continuity test on all my solder joints after they cool. That should catch a cold joint - anyway it has worked for me.  It's not necessary or a good practice to fill the solder lugs. Make a good mechanical connection to the solder tab with your pliers and just use enough solder to cover the wire. One more thing you need to do is trim the tag ends as short as you can to avoid electrical shorts.

Take your time and have fun!

Ken

Ken Goss


Offline jboehle

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Reply #2 on: May 04, 2014, 03:55:19 PM
They look okay but it's hard to tell for sure as most of the pictures are somewhat out of focus.  You don't need to set it that hot.  600-650F should be sufficient.



Offline Paul Birkeland

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Reply #3 on: May 04, 2014, 06:01:11 PM
If you use about 1/3 of the solder that those joints have, the job will be a bit easier, and the quality of work will go up.

The joints in the photos look like they will work well.  One way to test for cold joints is to jiggle the wire going into the joint to see if it's locked in place, or if it appears to move from within in the solder.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Grainger49

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Reply #4 on: May 05, 2014, 01:01:06 AM
It is always good to ask.  And here is the place to ask.

As Ken said, try checking for a good solder joint with a meter.  Adding what Paul said, wiggle the wire as you measure to see if the resistance changes.  This requires a pair of jumpers, listed as necessary tool in the Tech Tools folder.  Good solder joints start with a hook on the end of the wire or component, a crimp onto the terminal or tube pin and then solder and heat.

A quick note about checking continuity.  Most meters today are digital.  When checking for a good solder joint, continuity, set the meter on ohms (lowest scale if you have scales) and touch the meter leads together.  This will not be zero.  It will be the resistance of the two leads.  It will be under one ohm.  So anything below one ohm is considered zero.





Offline jamiet

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Reply #5 on: May 05, 2014, 04:06:50 AM
Thank you. I'm waiting on a multimeter and flush cut pliers.

The wire strippers I have, have the wire cutter towards the inside of the handle and it's hard to get in really close with them.

-Jamie.


Offline Grainger49

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Reply #6 on: May 05, 2014, 05:06:54 AM



Offline jamiet

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Reply #7 on: May 07, 2014, 05:56:25 AM
It looks like all the solder joints are ok per the continuity checks. Also trimmed off the excess pieces of wire.

I'm going to proceed with the build this evening.

I'd like to really understand the schematic so I can move on to bigger tube projects in the future. Any suggestions on how I can learn as I go? I like that the manual explains things like "the tube heater comes from the transformer secondary winding 6.3 v". Things like that make it easy to understand what is going on after looking at the tube datasheets. I've ordered Morgan Jones Valve Amplifiers 4th edition.

-Jamie.