Crack Hum from loose 220uF Caps [solved]

[remedy]

Hey,

So I've been going crazy trying to eliminate the hum from my crack, and since I accidentally touched my soldering iron to the protective film on my 220uF caps (yes, all 3), I bought replacements. I'm certain the hum I get is from the new caps because the two on the side by the power plug are both pretty easy to wiggle, and I flipped the crack over with it on and poked them with a chopstick and the hum would fade in and out depending on how much I moved them.

So my question is how do I solder them in well enough to keep them from moving at all? I have extra 220uF replacements so I can take these ones out and start again, but the leads on the caps are so short that I have issues getting them to be very sturdy in their placement.

I'm finding it especially difficult with the 220uF cap that has all the black wires go to it (I believe at terminal 14/15?) because theres so many things to fit in.

Any suggestions?

[Paul Birkeland]

If the snap-in caps are giving you trouble, you can try buying 220uF 250V leaded caps.

The trick to soldering them in is not to use too much solder, but rather to be patient with your heat so that the solder can flow and form a hard joint.

On snap-in caps, bend the little leads that poke out of the bottom so that they can pass through the terminal strips a bit.

-PB

[remedy]

If the snap-in caps are giving you trouble, you can try buying 220uF 250V leaded caps.

The trick to soldering them in is not to use too much solder, but rather to be patient with your heat so that the solder can flow and form a hard joint.

On snap-in caps, bend the little leads that poke out of the bottom so that they can pass through the terminal strips a bit.

-PB

Gotcha! I think I've just been using too much solder hoping it covers everything. I'll try try again with the extra caps I have with less solder and bending the leads a little more.

[Paul Birkeland]

Yeah, solder is like mortar in brick and mortar construction.

You want just enough to take up the space between the bricks, as they don't fit together all that tightly, but no more beyond that.

-PB

[remedy]

Removed the solder from the joints of the caps and resoldered them, the hum is less prominent now and doesn't change with and prodding or movement of the caps.

Though I did just unplug the rca jacks to see if it was my source, and the hum is completely gone. Does that mean it's from my source? I never used to have the hum when I first built the crack (and then I went and messed with it to "perfect" the amateur soldering mistakes).  That was with the same source too. My RCA cables are shielded and braided too.

[Doc B.]

Yup, if the hum is gone when you pull the cables then it is coming in from ahead of the Crack. Whch means either your source component or more likely your cables are picking up hum. Try different cables if you have some.

[remedy]

Just tried a spare set of RCA cables, same issue. Also out of curiosity I turned my source off and it still has the hum but when I unplug the power cable from the source the hum is gone.

So I guess it's definitely my source then. Guess I'll try a few different power cables or something, maybe connect it to another circuit if I can.

[Doc B.]

That's a ground loop. Are both pieces of gear plugged into the same circuit?

[remedy]

They're plugged into the same power strip on the same outlet. So I believe so?

[remedy]

And it's gone after using an extension cable to an outlet on another circuit. Doh!

Thanks for the help!

[Grainger49]

Does your source have a three pronged IEC power connector?  There are a lot of smaller sources that do not use a ground.  This is an invitation to ground loops.

A dedicated ground wire from the outlet (center screw) to the chassis/frame of the source might cure it if you don't want to leave the extension cord in place.