Help replacing cornwall type B-2 caps w/ crites replacement caps

[davestef]

Hi,

So I've put off replacing my cornwall I's caps for about two years. I'm off today and decided today was the day. I just went out and bought a soldering iron and some electronic solder. I opened up the back of the speaker. Disconnected the input and output wire, unscrewed the crossover from the speaker, and that's where I'm at. I still dont know how to solder, but I can learn from youtube. My main dilemma is what goes where. I'm looking at the schematic and not really getting it. Anyone have any advice? A walk through would be nice.

Cheers,

dave

[davestef]

heres the schematic

[davestef]

Heres the crites replacement for one speaker, the soldering iron i bought, and the solder. The hardware store by me only had a 12watt and a 40 watt soldering iron.

[davestef]

So i was able to figure out how to use the soldering iron. NOw I just need to know what goes where and what wires to solder together.

[Mongo171]

It looks like the iron and solder are too big for this project. I would suggest no-clean solder and flux. A pencil-tip iron will do you good for this project.

[djk]

Both the solder and the iron look fine for use on a network.

[DizRotus]

This reminds me of the old TV shows where the pilot of the small plane has a heart attack and the tower talks the passenger through landing the plane.

A few minutes on the phone would work well. Trying though typed posts would be difficult.

It's 7:40AM EDT USA . Send a PM or email with a phone number and I'll try to talk you down.

[Deang]

Dennis, I'm surprised to find you good with 60/40 and I think it's too thick -- since he's inexperienced, he might end up putting heat on things for too long. He's most likely to end up with either cold solder joints or dry joints.

I recommend 63/37 .031". 63/37 is eutectic, which means it goes from solid to liquid to solid almost instantaneously. It actually both melts and solidifies at almost the same temperature. The melting point is also about a 100 degrees below 60/40. 60/40 melts and solidifies over a range of temperatures, which means it takes longer to solidify once you remove the tip from the joint, increasing the chances of a cold solder joint. Speaking of tips, clean it constantly and put a little bit of fresh solder on it as you go from joint to joint.

Get out a piece of paper and trace out your crossover using the schematic. IOWs, make a physical drawing of the board while using the schematic, which is logical. It's a great way to learn the circuit and will help you not make a mistake as you move forward.

Bob still uses those cable tie screw mounts, an idea of mine after seeing them at Parts Express while checking out, but now only rarely use. The bottom of those things have hard sharp edges, and when you tighten the tie, they dig into the bottom of the capacitor. I also don't like the zip tie going across the middle and the pressure that's exerted onto the surface either. All of these caps are largely unprotected. Immediately under that teflon tape is the delicate film layer. So, when I do use those things, I cut a little piece of foam and lay it on the bottom of the bracket before I set the cap in it, and when I use the zip tie, I only use the amount of tension it takes to hold the cap in place. I often follow up with a bit of hot melt to stop things from vibrating out of place. I prefer these things:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=080-847

On larger capacitors, I wrap one around each end of the capacitor, and then run screws through the holes and into the wood. The ends of capacitors are usually epoxy end caps, so you tighten can tighten a little without risking damage to the capacitor. On smaller caps, I just use one, but don't bear down with the tie -- just enough to secure it. In the picture below, I really didn't get the ties on the bigger cap out to the edge far enough, but with the crossovers that don't go inside the speaker, I don't crank down on the zip ties anyway.

[djk]

"The melting point is also about a 100 degrees below 60/40"

60/40 Tin/lead (Sn/Pb) which melts at 370 °F or 188 °C and
63/37 Sn/Pb used principally in electrical/electronic work. The 63/37 is
a eutectic alloy, which:
has the lowest melting point (183 °C or 361.4 °F) of all the tin/lead alloys; Slightly cheaper than Sn₆₃Pb₃₇, Sn₆₀Pb₄₀ is often used instead for cost reasons as the melting point difference is insignificant in practice.

Dean, are you freaking out about 5°C?

If he ties the part down before soldering, it won't move while solidifying.

While the gauge of the solder is large, these aren't surface mount parts either.

Bad joints are generally from too little heat and movement of the joint after removing the heat. The only bad joints I've seen on heritage Klipsch networks came from not enough heat. I use a 45W iron-clad tip with a permanently attached heater element (Ungar), it is huge, and has enough mass to get the job done quickly. I use a Metcal at work, they can run to $1000 (without tips).

I use Sn₆₂Pb₃₆Ag₂ on personal projects, it melts at 179°C. Soldering to silver generally requires silver in the solder.

Soldering to gold: always tin gold plated parts, then wick all the solder off and re-solder with 2% Ag. Failure to remove the gold plating will result in tin-embrittlement down the road (the gold migrates into the tin), resulting in fractured joints. Using silver (after removing the gold) improves the fracture strength.

[Deang]

I will most definitely freak out over 5 degrees centigrade. Hmm, I really didn't realize there was so little difference.

I've got some SAC 305 when I have to solder silver. I like it don't like it -- I actually don't know what to think about it.

If he ties the part down before soldering, it won't move while solidifying.

That depends, if you know what I mean.

[tube fanatic]

A 40 watt iron with 60/40 rosin core solder is just fine for this type of work. Many folks who are just learning to solder tend to overheat the connection; with that in mind, I'd buy a small alligator clip (copper preferred) and clip it onto the capacitor lead as close to the body as possible to act as a heat sink (if, by chance, you have a small hemostat around, that will work also.) It's extremely effective at preventing component damage from overheating. As was mentioned, keep the tip clean. It also can't hurt to apply a tiny amount of solder to the iron's tip immediately before soldering to "prime the pump" a bit. Email me if you want additional advice or pointers.

Maynard

[Marvel]

I started using Sn₆₂Pb₃₆Ag2 when I wasdoing repair workon industrial knitting machine electronics. It was what the company used, and I liked it so well I began to use it for all my own projects. I still have a new, unopened one pound spool. The price has gone up considerably since I got it. [:|]

Bruce

[Deang]

So now I'm behind the curve. Yeesh.

[Daddy Dee]

Dean,

the screw down cable ties are cute little guys.

makes for neat work