My Turntable needs to be soldered.

March 20, 2005 9:29 PM

My Turntable will only play through one channel. I have a soldering question, because I have to replace the RCA cables. Can someone teach me how to properly solder audio equipment? I have never soldered before, but I am handy with electronics. The Turn Table in question is a Pioneer PL-10, a nice older one that goes well with vintage reciever. I bought it for $30 along with some scratched up first pressing Beatles albums. Basically, when the needle is down you can only hear one channel. There is absolutely no signal from the left RCA cable. When I reverse the plugs, the dead RCA cable is still dead.... just on the other channel.

I opened the record player and all the wires are connected and they look clean. The RCA cables have a light bulge in the middle of the wire and I am guessing that is the culprit. I don't mind soldering new RCA cables on it, but I have never soldered before.

Here is basically my question:
1. How do I properly remove the old RCA cable from the solder point?
2. Should I clean the connection before soldering?
3. How do I solder a new cable on, assuming I exposed the wires properly?

posted by Dean Keaton to technology (13 comments total)

In case anyone is wondering, yes I verified the cartridge is not mono.
posted by Dean Keaton at 9:30 PM on March 20, 2005

Get an adjustable heat soldering iron and set it fairly low. To remove something, put light tension on the wire by pulling on it while you place the hot iron to the soldered joint. You should be able to easily pull the wire away when the solder is melted.

If not, it may be stuck through the board and bent around the other side, in which case you'll have to heat the opposite side while you pull from the top. Not hard, just plan accordingly.

You shouldn't really need to clean any of the connections before soldering, but it does make the solder flow better if you get a little bottle of soldering flux, available from arts-n-crafts stores in the stained glass section. Apply a little of it with a wet paper towel to make things go smoother.

To solder a new wire, you'll want to prepare the stripped end with some solder before you attach it. Hold the wire steady while you rest your hot iron against the bare end to heat it up. Apply some solder to the iron and let the molten solder lightly coat the tip of the wire. This makes it much easier to attach the presoldered wire to the pad on the board later. Hold the presoldered tip onto the desired point, lightly rest your iron on the top, and everything fuses together without much fuss.

Other miscellaneous tips: Get very thin solder. You don't need the thick stuff from the plumbing section, you want the very thin stuff from radio shack or other electronics stores. Get pure solder, not the kind with a resin core. Use less solder than you think you'll need, it's probably enough. Use just as much heat as you need to melt the solder, never more. This means getting an adjustable iron. Some small components can be damaged easily by too much heat.
posted by odinsdream at 9:45 PM on March 20, 2005

*Apply a little of it with a  wet  paper towel to make things go smoother.
posted by odinsdream at 9:47 PM on March 20, 2005

Get thee to Radio Shack and purchase desoldering wick (braided metal floss) and a desoldering bulb, plus solder and a soldering iron if necessary. If you are buying solder ask the salesman to make sure you get the right thing, but a fine gauge 60/40 rosin core solder like this will do (no acid core). Skip the lead-free solders, they require much higher heat and are hard to work with. Apply heat to the joint with your solder iron, trapping the desoldering wick between the joint and your iron. As the solder melts draw the wick across the joint to allow it to absorb the melting solder. The bulb can be used to suck up large blobs, but follow with the wick anyway. (You may not need the bulb.) After you separate the parts remove any large amounts of solder remaining at the connection. You don't need to get to anal here. Tin the new wires by heating them and applying a little solder, then wrap them securely onto the connection. I cannot overemphasize the importance of a good physical connection. Remember, solder is not glue. Then apply heat to the wire and the joint, add solder by touching it to the wire or joint, but DO NOT ADD SOLDER BY TOUCHING IT TO THE SOLDERING IRON. After you have enough solder hold the iron on the joint for a few extra seconds and then remove it. The resulting joint should be shiny, if not it may be a cold joint which will adversely affect the sound and will ultimately fail. If so, try reheating with just a touch more solder. If that doesn't work, desolder and redo the joint.

You also want to properly tin the iron prior to soldering or desoldering. Heat it and apply a touch of solder to the tip and coating it with solder. Wipe any excess off on a wet sponge. The tiniest bead of solder on the tip prior to applying it to the joint aids in heat transfer. This is a small amount just to the heat moving, not anything that will really add to the joint. Soldering tip tinner and cleaner paste, also available from Radio Shack, helps once the tip starts oxidizing a little. With just one or two joints this hopefully won't be a problem.

On preview, yes an adjustable iron is nice, but you will be fine without it. Also, do not use solder flux, the Radio Shack solder has flux in its core. I wouldn't trust art store flux; if it has acid the joint will ultimately fail over time. Also, DO NOT rely on the amount of solder on the tinned wire to make the joint. Add more solder, and make sure it melts through contact with the wire and joint, not against the iron.
posted by caddis at 10:13 PM on March 20, 2005

Prior to soldering on a new cable, you may want to verify with a multimeter that in fact the cable is bad. Test the resistance from the joint to the cable end and it should be essentially zero. You may very well find that the real problem is a bad connection at the wire which attaches to the cartridge.
posted by caddis at 10:17 PM on March 20, 2005

I checked the cartridge wiring, I even plugged a different cartridge into it while checking. Should I just buy some RCA cables, or should I get some nice ones? I only need 2-3 feet at most.
posted by Dean Keaton at 10:27 PM on March 20, 2005

I almost forgot, thank you for the quick and relevant replies.
posted by Dean Keaton at 10:48 PM on March 20, 2005

For all manner of DIY cable goodness check out Jon Risch. Good cables can make a difference. For a really simple but good DIY cable get some Belden plenum rated CAT 5E cable; it has Teflon insulation (insulation affects the sound, really). Take out two sets of twisted pair cables and use these. Get some quality RCA plugs (Radio Shack has some OK plugs, the Parts Connexetion has even better parts) and you have a high end cable that will perform at least as well as $100 interconnects (isn't it just insane that many audiophiles consider $100 interconnects entry level?).
posted by caddis at 10:54 PM on March 20, 2005

You want a rosin core solder. A solder without rosin in the core will be a real pain to solder with, since the flux not only cleans the connection, but transmits the heat to the joint first, before the molten lead/tin. I usually reccomend 37/63 eutectic solder (ask the electronics store) with a 2% Activated Rosin Flux core. DO NOT GET ACID CORE OR ORGANIC CORE. Acid and organic core solder are useful for factories where the boards will be washed with water after soldering. You probably don't plan to do that.

A heat adjustable iron isn't necessary for this job, get a $10 cheap 30 watt (or less, at least 15 watt) jobbie for this, it's enough for a simple job like this.

Be sure to prep the iron the first time you use it by liberally spreading solder on the tip to seal it. Never file the tip. If it gets dirty, use your solder to clean the dirt up, then wipe the excess solder off on a wet cellulite sponge (normal household sponge).

Solder should be added by placing the solder wire at the point where your iron is heating the connection.

For extra cleaning, you can buy rosin electronics flux. I reccomend the liquid over the paste, although they are both pretty good.

If you are having a hard time soldering to REALLY cheap connectors, rough the soldering area up with a wire brush or sandpaper first to remove the chrome (solder doesn't stick well to this).

Excess flux can be removed with 99% Isopropyl Alcohol and a q-tip. You can buy flux remover, it's just Isopropyl Alcohol with some sort of detergent that moves the stuff out of the way.

To minimize heat retention when soldering a connector, place the connector in vise-grips or a real vise (if you have one handy).

Oooo! #1 thing to remember: Slide the connector jacket over the cable before you start soldering. :-D

caddis, I defy you to prove to me that any normal wire insulation affects anything below 20 kHz (the threshold of human hearing). Insulation does affect your wallet, though. :)
posted by shepd at 11:15 PM on March 20, 2005

Thanks shepd. Actually, I am part of another audio enthusiast forum and they are sending me a pair of $500 speaker wires to test the difference between them and my el cheapo bottom of the line Monster wires.

Since my reciever has dual audio outs, I am going to have my girlfriend blind switch them and listen through a few albums (jazz, rock, punk and contemporary) to tell if there is a difference. I honestly doubt there will be with my equipment. Maybe if I had some unbelievably expensive stuff I might tell a difference. I agree that for the most part expensive wiring is a joke, but then again I have been asked to write a report on my findings.
posted by Dean Keaton at 11:24 PM on March 20, 2005

Solder should be added by placing the solder wire at the point where your iron is heating the connection.

I am pretty sure shepd means adjacent here. The absolutely most important rule of soldering is making sure that the parts to be soldered are hot enough to melt solder otherwise the joint will be imperfect. That is why soldering tutorials emphasize making sure you melt the solder by touching it to the parts being soldered and not to the iron. If the parts are almost hot enough and you touch the solder to the iron it might transfer enough heat to the parts to make a good joint, or it might not. If however, the parts themselves impart the heat necessary to melt the solder then you know the parts are hot enough.

Eutectic solder is a bit better than 60/40 but I don't think you will find it at Radio Shack.

In certain audio circles, effects of cable insulation on the sound can be argued with similar intensity to abortion debates. I will just leave it as we agree to disagree.
posted by caddis at 12:16 AM on March 21, 2005

The absolutely most important rule of soldering is making sure that the parts to be soldered are hot enough to melt solder otherwise the joint will be imperfect.

That's important enough to say again, in bold. In other words. The soldering iron does not melt the solder. The soldering iron heats the parts to be joined. *They* melt the solder.

The flux in the solder will only last about a second, so you can't put a big blob onto the iron, then hold it on the joint and get a good connection.

One way to get the idea. Strip and twist two wires together. Hold the iron against the twist. Hold the solder about 1/8th of an inch away from the iron, touching the wire. Wait. The wire will warm up to the melting point of the solder, then the solder will melt. Feed it into the wire. The (now liquid, with now liquid flux) will wick into the wire. Once the whole joint is silvery, lift the iron and solder. Wait a couple of seconds for the joint to cool, and you should have a well soldered joint.

Do this a few times with scraps of wire until you feel comfortable with holding the iron, and understand how solder melts and flows, before you poke at a circuit board.

Note Well: Don't leave the iron on the board too long. You can delaminate the circuit board and/or lift circuit traces. If the joint isn't getting hot enough to melt solder in two seconds, you need a stronger iron. A 25-35W should be plenty.

Eutectic solder is a bit better than 60/40 but I don't think you will find it at Radio Shack.

Well, technically, 60/40 is aeutetic alloy (that is, it has a lower melting point than either of the metals that make up the alloy.) The problem with 63/37, which is the eutetic point for Sn3Pb alloy, is that it solidifies too quickly, making it hard to get good flow. 60/40 is more than adequate for this application.
posted by eriko at 4:32 AM on March 21, 2005

I have had very good experience wetting the iron a little (with solder, not water, duh!), so there is a small ball of solder on the tip. Applying that to the work, and then adding more solder right where the work touches the tip.

The reason I find this better... When the tip is dry the contact patch with the work is teensy tiny. You need to have a wet iron to get good heat flow from the tip to the work.

Improving the heat flow by using a wet tip has huge benefits. You want the target spot to heat up, not the rest of the object (think melting plastic). If heat flows from the tip to the work fast there is less time for the heat to spread.

odinsdream: Get an adjustable heat soldering iron and set it fairly low.

For all the reasons I just listed that is pretty bad advice. Depending, of course, on what you mean by low... My iron is set at 350 C right now, I wouldn't think twice about boosting it to 400 C (700-800 F).

caddis: Get thee to Radio Shack and purchase desoldering wick (braided metal floss)

I hate the stuff! If you want to desolder something just use a solder sucker. If it isn't doing a good job add a little more solder to the spot, then try again. The bit of solder to be sucked needs to be large enough to catch the moving air (like a parachute, I guess), so adding more solder actually does make sense. I'm sure desolder wick has a purpose, but I have never figured out what it is.
posted by Chuckles at 5:54 PM on March 21, 2005