REPLACE YOUR GUITAR AMP’S FAULTY INPUT JACK

Your guitar amplifier is useless if its input jack is faulty: either your signal is unable to pass through the jack or it’s distorted dramatically (and not the good kind of distortion). Given the time, effort, and materials needed to diagnose and repair a faulty input jack, you’re better off simply replacing the jack altogether. And you don’t need an extensive knowledge of guitar amps to do this simple repair. What you’ll need are a mono input jack, a soldering iron, and solder made for electronics — not to mention experience with soldering.

1. Plug in your soldering iron or fire up your soldering station and give it a few minutes to warm up.
2. Unless you have an open-back amp you’ll need to remove the amp’s panel to access the electronics inside.
3. Unscrew the nut securing the jack to the panel. There will be two wires connected to the jack: the hot wire is the wire connected to the prong touching the input jack’s metal ring; and the ground wire is the wire connected to the prong touching the plastic ring.
4. Melt the solder connecting the wires to the faulty input jack by touching each solder joint with the tip of your soldering iron and then discard the faulty jack.
5. Lightly touch the soldering iron’s tip to your fresh solder to melt a drop on the tip. (You can use traditional leaded or lead-free solder; it doesn’t matter aside from the temperature you’ll use for your soldering iron. However, you should only use solder marked for use with electronics as other types of solder can corrode and damage your amp’s electronics.)
6. Touch the end of the hot wire to the replacement input jack’s prong connected to the metal ring.
7. Touch the drop of molten solder to the point where the input jack’s prong and the wire are touching. Once the heat from the soldering iron is removed the solder will harden rapidly and this will securely connect the wire and input jack.
8. Follow the same procedure outlined in the previous three steps to connect the ground wire to the prong connected to the plastic ring.
9. Insert the end of your replacement input jack in the hole left by the faulty jack. Secure your new input jack with the nut you removed from the faulty jack earlier.
10. If you needed to remove the guitar amp’s panel, replace the panel. (A final note: Your soldering iron will retain heat for several minutes after being unplugged, so it’s a good idea to wait at least fifteen minutes in order to give it time to cool down.)

TROUBLESHOOTING YOUR GUITAR’S VOLUME CONTROL

Your electric guitar’s volume and tone controls are a fast, convenient way to raise and lower your guitar’s bass, mid, treble, and output volume without having to make adjustments at the amplifier; this is extremely helpful when practicing and performing, enabling you to tweak your tone and volume in the middle of a song.

When your guitar’s volume control fails the wires and connections need to be inspected. You’ll want to use your digital multimeter (DMM) to measure the resistance in ohms of the volume potentiometer. Potentiometers, or pots, are the electronic components to which the guitar’s volume and tone knobs attach. The problem with your volume control can be easily isolated and repaired with this simple three-step troubleshooting guide.

(Note: You’ll need a digital multimeter and small Phillips-head screwdriver. Ensure that your guitar is not plugged in to anything while testing your volume controls and, if you have any active electronics, remove their batteries.)

Step One

Remove all plates, knobs, and pickguards preventing access to your guitar’s electronics. Gibson-style guitars usually have a plate on the back of the body that covers the guitar’s electronics. Fender-style guitars, on the other hand, are generally accessed from the front, requiring you to remove the pickguard and the knobs attached to the potentiometers.

Step Two

Check the volume control pot’s wires and connections for any loose soldering or shorts. A loose or broken connection might be the source of the problem and this can be easily fixed by resoldering the connection with your soldering iron.

Step Three

Next you’ll want to test the volume pot using your digital multimeter. Set the DMM’s meter dial to 200k on the ohm (Ω) section of the dial and then turn the guitar’s volume control all the way in one direction. Touch the digital multimeter’s probes to the middle terminal and one of the outside terminals (potentiometers have three terminals). After that turn the volume control in the opposite direction. Depending on the direction the knob is turned the reading on your DMM will increase or decrease. If the reading on your DMM doesn’t change or even show up you’ll know the volume pot is no longer functional and will need to be replaced. The good news is that volume pots are inexpensive and need simply to be soldered.

CLEANING AND MAINTAINING YOUR SOLDERING IRON

Properly caring for your soldering iron will result in lower melt times, cleaner soldering jobs, and a significantly longer iron life. Cleaning and taking care of your soldering iron is rather easy and you’ll only need everyday household items.

Cleaning Supplies

The first thing you’ll need is a sponge, due to its ability to hold water. When you rub a hot soldering iron tip on a wet sponge the solder contracts at a different rate than the soldering iron, which helps to knock off any residual solder clinging to the iron’s tip. (This is why soldering stations include a sponge.) The sponge should be damp — not soaked.

The next thing you’ll need is six hundred-grit sandpaper, which you’ll use on the tip only if it’s been abused by the previous technician, student, co-worker, etc. Paper will catch fire at around four hundred fifty degrees, so be sure that the soldering iron has had time to cool and make sure the soldering iron or station is unplugged.

Tip tinner/cleaner isn't necessary if you have some extra solder, but it may be worth buying and using if you have a high-dollar soldering iron or station. Most of the time solder will work just as well, though.

Two Cleaning Scenarios

Let’s say someone has left you with a cold and dirty soldering iron, which is of course a common scenario in college electronics labs and a lot of workplaces. If and only if the iron is cool lightly scuff the iron’s tip with your six hundred-grit (or higher) sandpaper until the tip regains its luster — you’re just trying to remove the oxidation, not the metal.

If your soldering iron is dirty but still hot, you’ll need to set your iron aside and allow it to heat — a minute and a half is generally sufficient. Once the iron has heated you’ll notice brown deposits on the tip: this is rosin. Take your iron and flick the tip against the damp sponge. Don’t hold the sponge in your hand.

You’re almost finished.

Tip Tinning

Once you've cleaned the iron it’s a good idea to tin the soldering iron’s tip, which you’ll do in our case by lightly coating the entire iron’s tip with solder. The solder will act as a buffer zone that serves to protect the iron from oxidation.

Choose a low-temperature solder so that the iron cools fairly quickly — that way you won’t fry the solder to the tip, which would completely defeat the purpose of cleaning your soldering iron or soldering station. I won’t go into details regarding tinning here, but you’ll find a number of helpful tutorials elsewhere online.

Take care of your soldering iron or soldering station and it will work flawlessly for years to come.

SERVO & STEPPER MOTORS IN CNC MACHINES

Computer Numeric Control (CNC) machines convert instructions into actions for controlling operating tools. Movement is triggered when alphanumerical codes are entered in a CNC machine, and they have several attached tools: laser cutters, routers, and cutting tips. Component design is automated using computer-aided design and computer-aided manufacturing programs. CNC machines use either servo or stepper motors, each having its own unique dis- and advantages.

Servo Motors

Servo motors transfer information to the CNC machine using closed-loop circuitry. A regular (DC or AC) motor is connected to an encoder with a fixed sensor: this encoder is why servo motors have high accuracy and resolution. The servo amp powers the motor and counts the steps made as well. The servo motor’s impressive torque-to-inertia ratio permits rapid load acceleration and, with light loads, efficiency may be as high as ninety percent.

The downside to using servo motors in CNC machines is they are more complicated to operate and typically more expensive than stepper motors. Servo motors are also more susceptible to damage from overheating and -loading because their ventilation system is easily contaminated at high speed. What’s more they require servicing once the brush has reached its two thousand-hour lifespan.

Stepper Motors

The stepper in stepper motor comes from the steps the motor makes, which are triggered by each signal pulse. Stepper motors are easy to operate, generally cost less than servo motors, and have a higher reported accuracy. Several loads can be driven without gearing due to stepper motors’ low-speed torque, allowing use of a timing belt and pulley reduction. Steppers usually use fifty to a hundred-pole brushless motors, whereas servo motors have only four to twelve poles. Steppers don’t require encoders.

Stepper control systems are optimal for applications requiring low-to-medium acceleration, high-holding torque, and the flexibility of open- or closed-loop operation.

Stepper motors are normally less efficient than servo motors. Smooth movement often necessitates microstepping because steppers are resonance prone. Their low torque-to-inertia ratio causes loads to accelerate less quickly. Steppers are louder than servo motors and, like servo motors, are prone to overheating at high performance. Lastly, stepper motors have a lower overall power output relative to their weight and size.

THE ROBOTS ARE COMING — FOR YOUR GUITAR

It’s tedious to tune up your guitar before you play, to tune between songs, and to retune to, say, drop D for one song — only to retune again after the song is over a couple minutes later. If you’re playing in a band you have to make sure that everyone is tuned to exactly the same notes, which gets trickier when you add certain instruments to the mix (e.g., mixing equally tempered instruments with ones that are stretch-tuned).

If you like lighter strings or are a heavy-handed player or, worse yet, if you’re a heavy-handed player who likes lighter strings, you’ll know how quickly and unexpectedly your guitar can go out of tune. A perfect take in the studio amounts to nothing if you’re not in tune. And nothing is as irritating as going out of tune in the middle of a song.

If you have multiple guitars, electric and acoustic, chances are you have multiple tuners, perhaps a clip-on tuner for your acoustic and a pedal tuner on your board for you electric guitar, and maybe you still have that cheapo tuner you got when you bought first guitar. Maybe you even have a high-dollar strobe tuner for setting your intonation. Good pedal tuners are around a hundred bucks, and there are plenty that cost more than that. And heaven help you if you’re searching for that elusive perfectly accurate tuner pedal that doesn't color your tone and has a display that’s easy to read in low light or if you have bad G.A.S. Not only do you have to pay for the tuners themselves, but you've got to shell out for batteries, patch cables, replacement switches, etc.

You get the picture. Tuners are kind of a giant pain in the you-know-what.

Imagine being able to switch from standard tuning to open G to DADGAD in a matter of seconds. Think about how much time you spend tuning when you could be playing. Those times when your guitar goes out of tune in the middle of a song.... What if you could roll off your volume pot, strum all six strings at once, turn your volume back up, and launch into the solo in the middle of a gig?

Self-tuning “robot” tuners have been around for a few years. Maybe you've seen Gibson’s Robot Guitar or their other high-end guitars (e.g., the Dusk Tiger) with robotic tuners built into the back of the headstock, or maybe you've seen Jimmy Page’s Les Paul Goldtop with the costly Transperformance robotic tuning system, which requires heavily modifying your guitar. Soon enough robotic tuners are going to be available on the mass market, and you’ll be able to retrofit practically any guitar.

The catch is that they’re probably going to be expensive.

You don’t have to wait, though, and you don’t have to pay a premium. Students and do-it-yourselfers have been building robotic guitar tuners for years now, using affordable stepper motors and various components you can get from an electronics parts supplier. If you've got chops with a soldering iron, why not give it a shot yourself?