The Ibanez Tube Screamer

Love it or hate it, when it came out, the Ibanez Tube Screamer TS808 was an innovative product which used a feedback loop with diode clipping to produce a distorted tone instead of overloading transistors.  Now the method of using feedback diodes is practically standard. 

Using feedback diodes to clip the signal gave a very predictable and controllable method to distort the signal.  Instead of relying on the (extremely) variable gain of transistors, the amount of gain is controlled by very easily calculated formulas.

The only transistors in the design serve to buffer the input and outputs (virtually any small signal transistor will work for this and not influence the sound in any appreciable way) and operate the bistable flip flop which controls the effect switching. 

The flip flop is at the heart of many modern pedals.  While it is not true bypass, the buffer on the input minimizes any tone loss.  In fact, it will have less tone loss than an effect pedal (such as a wah) with a non true bypass setup.  This is because the input impedance of the effect is quite high while a wah pedal (without a buffer or true bypass) has a comparitively low input impedance.  It is also cheaper to manufacture due to the reduced cost of transistors and tact switches than a traditional SPDT or DPDT (and now 3PDT) switch. 

The original TubeScreamer was designed and manufactured by Maxxon (who now produce effects under their own name).  Ibanez currently has a host of products that they market or have marketed as a Tube Screamer as well as products with different names and the same internals as a Tube Screamer.  Most noteable are the TS808, TS9, TS5, TS7, and TS9DX.  There are other models such as the TS808HW as well as a TS9 for bass which have come out recently. 

The TS808 and the TS9 are very similar with small differences in part values here and there.  Overall, the sound of the two pedals is quite similar and the easiest way to tell one from the other is the actual box design.  The TS808 has a flat square style button which I personally find to be a little bit unreliable (particularly on the reissues).  The TS9 on the other hand has a panel which activates a rather small tact switch underneath of it (DOD pedals used a VERY similar setup for some time).  Tact switches can be replaced for pennies.  The TS9DX looks like a TS9 except it has an extra knob which controls the clipping.  One thing that is less obvious is the quality of the pots on the TS9 are MUCH higher than the TS9DX.  Additionally, the pots are mounted onto two boards in the TS9DX so if you break a pot, be extremely careful when fitting a repacement or you will be buying a new pedal.  The boards damage easily and have traces which lift off easily as well.  This is not to say that the TS9DX is a bad or unreliable pedal.  In fact, it is one of my favorites. 

For some reason people believe that because you activate pedals with your feet, you can just kick them any old way.  I have even heard people going on about BOSS pedals' bullet proof steel case design.  Open up the battery door and look at the very delicate (and easily broken) switch that BOSS uses and then rethink how you abuse your pedals. 

The TS5 was part of the SoundTank series.  The sound tanks were small plastic enclosures (although the first few sound tanks released in blister packs were actually metal) designed to be very modestly priced.  They actually sound surprisingly good AND are very quiet in terms of noise.  In fact, the TS5 is much quieter with regard to noise than any other Tube Screamer I have ever used.  I have own multiple TS5's in the past and they were all quieter than any TS9, TS9DX, or TS808 I had used.  The tone of the TS5 was also mildly cleaner. 

The TS7 was a part of the ToneLok series.  The initial run of Tube Screamers from this series came in a green alloy case and eventually they were switched to a grey alloy.  I do not like these pedals.  They are built to be cheap and sound it.  The enclosures are squeaky and prone to breaking.  Fortunately, they have been discontinued and a return to the 9 series and their enclosures has been Ibanez's current offering of pedals. 

Some of these models may use different values or ICs but all more or less sound as though they came from the same family.  I have seen some Tube Screamers with metal film resistors (which supposedly have less thermal noise than carbon film) as well as different chips.  The TS9 and the TS9DX for example do not use the same IC.  The sound difference is noticeable to a discerning ear and both are recognizeable as Tube Screamers.  I have also heard an early reissue versus later reissue where the later reissue was much much brighter than the earlier model.  I can't really account for it (other than age and parts drift), but again, both were easily said to be Tube Screamers.  As a whole, the Tube Screamer family all pretty much sound the same or close enough to each other than whichever one suits your needs best is the one that works. 

I personally like the 9 series best because the enclosure is the strongest, doesn't use a goofy switch, and doesn't use a goofy adapter.

You can find more detailed circuit analysis online as well as mods, but what I'd really like to talk about now that I have given a bit of a background on the pedal is how to revive a dead Tube Screamer. 

Firstly, never overlook the obvious.  Always check your batteries, your adapters, cables, volume (on the guitar and amp), make sure your amp is plugged in, etc.  Sometimes it is the obvious things that slip past us the easiest.  If you are unsure of your setup, remove as much of it as possible until you are down to the guitar, a cord running into the effect, the effect, a cord running out of the effect, and the amplifier.  You may have other trouble that you are falsely attributing to the Tube Screamer.  In fact, make sure it is operating its own dedicated power supply be it a battery or adapter.  Have a friend try it as well to verify that you aren't forgetting something obvious.  This could save you a lot of trouble later on. 

Here are some common problems with Tube Screamers and how to remedy them.  Note, most of the issues here are talked about assuming you have a TS9, TS9DX, or TS808 (as they all share the same main board).  These techniques can be applied to any of the Tube Screamers, but the pedal disassembly, and part locations may be different. 

Does not work with a battery but works with an adapter - The adapter jack is broken.  This is usually caused by somebody using the wrong adapter and forcing it into the jack.  This in turn causes the switching adapter jack to become sprung and not short out when no adapter is used.  Hopefully if somebody did this, they at least used a properly rated adapter or else you may have other issues.  Sometimes the adapter jack is so badly mangled that the pedal won't work with an adapter either or will be intermittent.  The solution is to replace the adapter jack or if you never use the adapter to short the adapter jack internally and use the pedal with batteries only.  My advice, repair it correctly so as not to damage resale value should you decice to go that route. 

Also, look for broken circuit boards around the ground lug (which helps hold the board down to the enclosure).  This is common when the adapter jack is forced.  To repair this break, take a piece of solid wire and strip all of the insulation off.  Bend it around into a circle.  and solder it over the ground lug pads.  For additionaly reinforcement of the board, you can carefully use super glue or epoxy to mend the crack.  Using glue may not be necessary depending on the size of the crack. 

The effect does not work at all or only the clean sound comes through - This is almost always caused by using the wrong adapter but there are exceptions to this.  Sometimes a bad switch simply will not switch leading you to believe that the effect is not working.  The first place to look is at the protection diode.  This is the diode located closest to the adapter jack and the ground lug.  It is a larger diode that is used to shunt an adapter with the wrong polarity to gound.  This will not protect against using an AC adapter nor will it protect against using too high a voltage adapter.  If your adapter is putting out more than 10 volts, do not use it.  A brand new alkaline 9 volt battery will actually put out closer to 10 volts.  

What happens when you plug in the wrong polarity adapter?  The diode begins to conduct around .6 volts.  As far as the adapter is concerned, it sees a dead short and begins to draw infinite current (or whatever current it can draw before it overheats and destroys itself).  Once this happens, it is a contest to see which will destroy itself first, the diode or the adapter.  If the diode goes first, two things can happen, the diode can become open or the diode can short.  Both are bad and both should lead to the immediate replacement of this diode.  If the diode shorts, the pedal will never turn on as it will never get power.  The batteries will also get hot as will the adapters.  If the diode is open, the pedal is no longer protected.  Damage is also likely to have occurred elsewhere. 

The diode can be replaced with just about any diode but the 1N4007 is a pretty standard pick as it is robust enough to handle a shorted situation from an adapter for a brief moment without blowing.  Observe correct polarity when replacing this part.

Additionally, you may need to replace the IC in the pedal.  There is a lot of hype around the JRC4558D.  These were originally made by Japan Radio Corporation.  They are now being made by the New Japan Radio Corporation (NJRC) and are basically the same part.  For extended options, you could put a socket in and try different chips and pick which sounds best to your ears.  If you can find a chip with a marking 4558DD, the double D is an extra low noise variant. 

If an AC supply was used, you will almost definitely need to replace the power filtering capactor.  This should be pretty obvious as they literally explode when the wrong polarity is used as they short out.  There may be a stringy substance that looks kind of like the insides of a cigarette filter hanging around an electrolytic capacitor.  That is the one you want to replace. 

In dealing with shorted supplies, I never had to replace any other parts than those 3 to get a Tube Screamer working again. 

However, there are still other problems...like that pesky switch...

The effect does not switch - You have no reason to suspect a bad chip or anything of the like but the effect won't switch.  How do you test to find out if you have a bad switch?  On a TS9 open the battery door.  Remove the battery foam.  It pulls out.  Most of the time it will fall apart, but if you are careful and take your time, you might be able to get it out without completely destroying it.  There will be a small board beneath the foam.  This board has two wires running to it connected to a momentary tact switch.  Take a screwdriver and short the two leads or the tact switch itself.  If the effect switches, you have a bad switch.  Just about any good quality tact switch of the correct size will work. 

This switch is not under foam on the 5 series pedals.  They also use a much different switch.  This switch is the same as SOME but not all of the switches on the 7 series.  From what I understand, this has to do with country of origin of the pedal.  These switches may be available online or perhaps with some clever improvising or rehousing, the pedal can be revived. 

Another thing that can cause the effect not to switch is either a short or a cold solder joint in the flip flop section of the board.  The resistors that have the ceramic caps tied to them are a good place to look for cold solder joints.  Any close pads may also have too much solder and might be shorting them.  Check carefully.  Use a magnifying glass if need be.  Obviously, if the effect was once working, I'd check for cold joints and not worry to much about shorted pads as that would have been a day 1 observation. 

The light changes but the effect is either always clean or always dirty - You have a short in the flip flop section of the board or one of the FETs used to isolate the input and output of the effect are not getting powered correctly.  Touch up all of the solder joints in that region with some fresh solder.  Check any pads that might be close for solder bridges. 

The tone control makes a lot of noise when it is above or below the 12 o'clock position - I have only ever seen this once, but the solution was replacing the bad tantalum capacitor for the tone control.  This was a frustrating problem as I had never encountered a bad tantalum capacitor before.  Be sure to observe correct polarity when replacing it and have another tantalum capacitor handy as they are very small physically and have high capacitance values that you will not be able to get a poly film style cap to fit and have the correct value. 

If all else fails, you could always do what most people end up doing anyway, and return your pedal to a Guitar Center or Sam Ash type of store.  These stores do a lot of business with Ibanez.  Consequently, Ibanez does not even question their returns and will credit them.  This translates to you getting a new pedal at little or no cost.  You can decide on the morality of it. 

I'm sure I missed something so if you have a unique situation, feel free to message me or post a comment and I will be sure to respond.