Hum from crack - tried resoldering

[shujinko]

No change... I'm concerned that at this point I'm doing more harm than good resoldering everything.  I'm also seeing that my soldering iron is too hot.  Its 60 watts and seems to be causing coloration and browning/blackening of the solder (I'm sure there are more accurate terms for this) if I use it after it's warmed up for a bit.

I took a few pictures in case there's something that jumps out.  Let me know if you want me to take more pictures of anything in particular.

I'm not really sure what to do at this point.  Here are some things I'm considering.  Please let me know which of these you guys think I should do.

• Buy a temperature-controlled soldering iron.
• Continue to try to resolder things.
• Redo wires that don't look great.
• Completely dismantle the Crack and rebuild it.
• Guess at a possible failing part(s) and replace it/them.
• Send the Crack in for repair.
• Buy a whole new Crack.

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[Paul Birkeland]

The LED installation to A8 is kinda funky.  When the leads are left that long, the LED can move around and short out to adjacent sockets.

The soldering on the ground tab at the back looks like a potential problem.

(The brown/black coming out of your solder is the flux, that's normal.  60W isn't too much)

[Grainger49]

I'm going with PB/CB, the solder joint at A8 looks missing in the next to the last photograph.  There may be a good solder joint on the other side, but I don't see any there in that photograph.

[shujinko]

Thanks for looking.  I addressed those and no difference, unfortunately.  Always happy to take more pictures if you need.


A8 is soldered around back and looks okay -- here's another screenshot.  The LED legs aren't close to any other socket leads or exposed wires, but if you think I should clip them down I certainly can.

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I added a bit of solder and cleaned things up as best I could on that ground tab (unless you were talking about a different one).

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[Doc B.]

Your soldering iron isn't too hot. As far as I can tell it's too cold. Those joints aren't smooth and shiny like a hot iron tip would help you to achieve. It could just be that you are using a tip that is too fat to allow you to get right into the "inside corner" of the joint between wire and terminal. If you used lead free solder that may be part of the problem too because it requires a rather high temperature. If the amp was on my bench I would reheat all the joints on the bad side and add just a little bit of 63/37 solder to each joint to get as smooth a joint as possible. 

[shujinko]

Okay, I'll give that a go.

I used a two-temp soldering gun to build it and it may have been cooler than what I'm using now.  I'm also not sure of the solder I used (it was from a friend), but my guess is that it was 60/40 because it flowed pretty well.  When I replaced the power switch recently (after the hum started) I did try silver solder, which I had never used it before, but then stopped because of how poor it flowed.  It was only used on the switch connections, and they seem okay.  Currently I have rosin core 60/40 and that's what I've been using in my recent touch-ups with the 60 watt iron.  Do you think that's okay or should I get some 63/37?  Should I attempt to remove much of the existing solder using a sucker?  If so, any recommendations on one?  I don't have one currently.

And just to clarify, when you say "the bad side", you mean the side with less visible solder, or the side's that's aren't smooth and shiny?

Are there any videos, pictures, or tutorials out there that you guys would recommend that would be especially helpful for this project?  I've watched a couple "how to solder" videos, but maybe I would do a better job if someone provided some pictures of properly soldered connections on their Crack?

Thanks for all the help.

[Paul Birkeland]

I'm also not sure of the solder I used (it was from a friend)

You're very lucky that this wasn't plumbers' solder (it eats holes in the chassis plate). 

Solder guns tend to have a lot of power, but very little control.  It can be hard to get the gun tip up against the parts your soldering, so the heat doesn't transfer that well. 

60/40 or 63/37 will work, just be sure there's some lead in there.