[MD1032]

 

OK, so, I built a cmoy the day before I left for Wisconsin. Might not have been the brightest idea but it didn't take too long and it was a lot of fun. Here's a picture.
 
http://img.photobucket.com/albums/v451/MD1032/Cmoy/IMG_2178.jpg
 
I made a mistake when buying supplies. I bought Radio Shack 18 AWG stranded hookup wire when I should have opted for 20 or 22 AWG. I also made a mistake when installing it, that is, I used way too much of it without realizing I'd have to cram it all into a case. No biggie, I can always rewire, although I likely won't.
 
The problem I'm having is with the Panasonic EVJ pot. I will never buy a pot that looks like this with the 6 pins straight in a row again if I can help it because soldering 18 AWG wire into there while avoiding contact is an art...not that I've had problems with solder bridges, but why would I want to put something with that kind of short-circuit danger into a portable amp I will be banging around like crazy?
 
I soldered it in once. It worked great but it had intermittent shorts. I desoldered it and soldered the wires together. Great! Amp works fine, sounds amazing, rock solid, I can throw it across the room and wiggle all the wires and the sound doesn't stop....my soldering and wiring work is not in question here. Solder the pot back in. Working great, sounds fine across the whole range of the pot. I fold the wires into place and case it up, still shorting. Rip it out, re-solder the wires together, check like crazy for flakey wiring and such...none, amp works fine. Solder the pot back in, case it up, shorts galore, remove it to find out the pins are shot and one has broken off from repeated installation.
 
TL;DR Pot's shot, look, it's no big deal, I can order another 100 Panasonic EVJ pots and keep soldering until I get the perfect alignment and none of the wires are banging into each other or anything else, but I would like a recommendation for a different pot that has the standard 3x3 pinout config and a way to mount it to the case.
 
I ordered an alps pot that I thought would be good (mouser part #688-RK12L12C0C0V), but I forgot that the particular model I bought didn't have threads and a nut for installation on a case. I might use a higher than 10K pot in the end, though. The gain is very high and I don't feel like changing the resistors to change the gain when I can just use a different pot to get the same effect.
 
The reason I even did all this is because I now have a Hakko 936 soldering station which made soldering all of this a breeze, and then some. I don't know how, but I seem to have ruined my soldering tip already. My next question is: how did I do it? The tip has some spotted black areas that will no longer retain solder and it just generally works terribly. I tinned it regularly and towards the end I used the Radio Shack tip tinner and cleaner...it's this gray-looking hard stuff that tins the tip and sizzles like crazy when you dunk the tip in it...I hope I didn't nuke the plating on the tip with this stuff. The other suspicion I have is that I did not use enough water on the sponge or I let my sponge get too dirty. I also didn't use softened or deionized water on the sponge, although I doubt this is a problem since the water in my area rarely has more than 20 ppm hardness. I will order more tips, they're very cheap.
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[nikongod]

Remind me before the next time we meet and I will bring you a bunch of very bright yellow solid-core 30ga silver plated copper. Its awesometoast for hookup wiring, especially when you have pins really close together like on those little pots. 
 
The 10Kohm pot will have pretty much the same volume control range as the 100Kohm one, although there are some advantages as far as noise is concerned. If you have too much gain change the feedback resistors.
 
To tin the iron, you are supposed to put solder directly on the tip. I usually aim for about the size of a small drop of water. Let it sit there for a moment, then wipe it off on the sponge and repeat a few times if necessary. Tips for high-end soldering stations last practically forever in hobyist use. 

 

[MD1032]

The problem I usually have is that when I put that small drop of solder on it, it likes to cling to one area rather than evenly coating the whole tip the way it does when it's a fresh tip.
 
50K ~= 10K? I forgot that it's logarithmic, that makes sense.

 

[tomb]

One solution is simply to cut a piece of perfboard to match the pins, stick the pot's pins through the perfboard, then solder to the pins underneath.  It may take some clamps to get the first pin soldered, but once you do that, the perfboard will hold in place.
 
The EVJ is made for a PCB mounting.  Any way you look at it, it's a kludge to air-wire it.  That said, the EVJ is a better performing pot than the Alps you referenced.
 
Yeah, that Radio Shack stuff is acid, if it's the stuff I'm thinking about.  Hakko tips will last a really, really, really long time, as long as you only 1) use the wet sponge that Hakko provides or 2) use brass wool.  Get a new tip - they're cheap enough and easy to replace.

 

[MD1032]

I thought of doing that, however, the 6 pins on the EVJ are exactly the same size as 5 holes on my perfboard...it doesn't fit. I could bend the pins, but I've already proven that they are not designed to be bent in any way and easily snap off.
 
You're right, my problems started when I decided to use elaborate means of cleaning the tip. I should have just stuck with the sponge.
 
The Radio Shack stuff is definitely acid, but then again, so are all fluxes. I think the problem is that it contains something else in addition to the tin and flux that eats away at the plating on the tip. If I tin it with the RS stuff and then put it on the stand, a glass-like residue will eventually develop.