Solder joints

[cool9]

I have my newly acquired Sansui AU-517 amp torn apart and I noticed a couple solder joints which are touching one another and I wonder if I should rework these joints or not. (The amp does works good and haven't noticed any working problems.)
(1) The photo on left is the bass/treble board and some wires coming from the tone board have large joints which touch a few resistor solder joints.
(2) Photo on the right is the tone board and those same wires from bass/treble board have large joints which run into a few resistor joints.
(3) Also wanted to know if a board can be damaged if a 40W solder iron is in contact with a solder joint too long. (I read not to keep an iron in contact with a capacitor joint for more than 10 seconds when desoldering for fear of damaging the cap.)
(4) Finally, I wanted to know how to use braided solder to remove existing solder in a joint. (Maybe I'll go to youtube and try to find a tutorial on that).

P.S. Were these circuit boards hand-soldered in the 70's?

 

[kaplang]

As the saying goes "If it ain't broke don't fix it"

 

[KingBubba]

The key for those type of situations is to look at the trace under the joint. You will notice that all those joints in the second picture share a common trace so the are all okay. I can't see the trace in the first pic, but my guess is that they all share a common trace. You are alright.

 

[Hyperion]

I have my newly acquired Sansui AU-517 amp torn apart and I noticed a couple solder joints which are touching one another and I wonder if I should rework these joints or not. (The amp does works good and haven't noticed any working problems.)
(1) The photo on left is the bass/treble board and some wires coming from the tone board have large joints which touch a few resistor solder joints.
(2) Photo on the right is the tone board and those same wires from bass/treble board have large joints which run into a few resistor joints.

What kaplang said - leave them alone, they look a bit blobby but alright.

(3) Also wanted to know if a board can be damaged if a 40W solder iron is in contact with a solder joint too long. (I read not to keep an iron in contact with a capacitor joint for more than 10 seconds when desoldering for fear of damaging the cap.)

If you have to keep your iron on a joint for more than 2 seconds, your iron is not hot enough - or you are just not doing it right. 40w is fine, is it temperature controlled?

(4) Finally, I wanted to know how to use braided solder to remove existing solder in a joint. (Maybe I'll go to youtube and try to find a tutorial on that).

That's a good idea - a picture is worth a thousand words.

P.S. Were these circuit boards hand-soldered in the 70's?

Some were, some weren't, and those that were 'flow soldered' (machine) usually had to be hand worked afterwards to add bigger or more delicate components.

 

[glen65]

I have my newly acquired Sansui AU-517 amp torn apart and I noticed a couple solder joints which are touching one another and I wonder if I should rework these joints or not. (The amp does works good and haven't noticed any working problems.)
(1) The photo on left is the bass/treble board and some wires coming from the tone board have large joints which touch a few resistor solder joints.
(2) Photo on the right is the tone board and those same wires from bass/treble board have large joints which run into a few resistor joints.
(3) Also wanted to know if a board can be damaged if a 40W solder iron is in contact with a solder joint too long. (I read not to keep an iron in contact with a capacitor joint for more than 10 seconds when desoldering for fear of damaging the cap.)
(4) Finally, I wanted to know how to use braided solder to remove existing solder in a joint. (Maybe I'll go to youtube and try to find a tutorial on that).

P.S. Were these circuit boards hand-soldered in the 70's?

Don't see anything touching together that's not supposed to be.

 

[AAA3330]

The key for those type of situations is to look at the trace under the joint. You will notice that all those joints in the second picture share a common trace so the are all okay. I can't see the trace in the first pic, but my guess is that they all share a common trace. You are alright.

+1 It is common to see joints of a common trace flowed together this way. Sometimes when soldering it is easy to bridge adjacent traces that shouldn't be connected. Just need to be watchful for that.

 

[whoaru99]

Braid / solder wick is fairly easy to use.

What I do is to melt a tiny bit of solder on to the tip of the iron, just a very small drop, then lay the wick on the joint to be desoldered. Next, put the tip of the soldering iron with the small drop of solder directly on the part of the wick that is over the joint. Apply a bit of pressure, squeezing the braid between the joint and the soldering iron tip. Give a second or two for the heat to conduct and melt the solder in the joint (that tiny drop of solder on the tip helps that) and it should just suck that old solder into the braid.

If the joint is larger, you may need to work the braid and iron a bit toward a fresh area of the wick as it will only pull so much solder in a given area of wick. Very large joints (with respect to small lead wires and component traces) might be better off using a solder sucker, or double up/triple up the braid.

 

[Detailman]

For circuit board work on vintage usually 25w is prefered.
Also generally come with a smaller tip that makes it easier to get into tight spots.
Don't know what type iron you are using but different tips are available for most.

40w is a little high for this work.