The Repair Bench: Ibanez TS9 Tube Screamer

| March 29, 2011 | 20 Comments

Learning how to troubleshoot electronic circuits is one of the handiest skills anyone can have if they are building or modifying amplifiers or effect pedals. At some point you’ll power-up a circuit and find that it doesn’t work, and then what? For this reason we write “The Repair Bench” section of Guitar Kit Builder about our own troubleshooting of amplifiers and other devices, to pass along to the reader the thought process, tips and techniques of troubleshooting electronic equipment.

IBANEZ TS9 TUBE SCREAMER

In this edition of The Repair Bench we troubleshoot an Ibanez TS9 Tube Screamer effect pedal. This is one of the most common and well-known effect pedals in use by guitar players, so we won’t describe it further. We received this pedal to repair and then modify. We’ll cover the modification in a later article. The owner reported that the pedal simply stopped working at some point.

INITIAL ASSESSMENT

Our visual inspection of the exterior showed it to be in typical used condition. The silver label from the back of the pedal was missing, so the serial number could not be identified, but this appears to be what Analogman calls a “2nd version reissue” due to the “Maxon” imprint on the inside of the battery cover.

Opening the case we found the printed circuit board marked “Maxon KU” with a Toshiba TA75558P op amp chip. Viewing the underside of the printed circuit (PC) board showed it to be clean, with no evidence of prior repairs, which is always a welcome finding.

We hooked up the pedal to an AC power supply, plugged in a Fender 1952 Telecaster Reissue, and connected the output to the Carvin SX200 amplifier we recently repaired in a prior edition of The Repair Bench. This test setup confirmed what the owner reported – no output sound with the effect in or out.

We decided to trace the signal with an oscilloscope, but while moving the board around to get it ready, we heard a sudden “bleeep” sound through the amp. By holding the board at a particular angle we were able to momentarily get an output signal. We concluded that we had an intermittent situation. Finding the cause of an intermittent problem can sometimes be difficult. Our procedure is to use an insulated probe or “orange stick” to gently nudge each wire and component to attempt to isolate an intermittent mechanical connection. In this case we quickly found that moving the purple #13 wire from the PC board to the level control caused the sound to cut-in and cut-out. Further inspection revealed that the potentiometer pin connected to the purple wire was touching the metal case of the adjacent tone control (see photo). This can happen when the potentiometer has rotated from its original mounting position, perhaps due to becoming loose from vibration, or perhaps from someone continuing to turn the level control higher when it has already been turned to its maximum.

We loosened the potentiometer mounting nut, rotated the pot to its proper position (photo below) and tightened the nut. Some more testing with the pedal showed it now to be working properly.

As some of our recent repair projects have shown, we don’t always get repair projects that are quite this easy, but they do happen. Our next article on this pedal will cover some modifications for better tone.

Category: Kit Building 101, The Repair Bench

Comments (20)

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  1. avatar todd says:

    I have the same pedal.I’ve had it since the early 80’s,I could never figure out how it was suppose to work.After reading your article I found the same problem with the purple wire touching the tone pot.I wonder if this could be a manufacturing defect? The Pedal screams now. Thanks for showing a problem with an easy fix that was something that could easily be overlooked.

  2. avatar guitarkitbuilder says:

    Todd, we’re glad to hear that this fix worked for you too, and thanks for leaving us a comment.

  3. avatar conorparnell says:

    Hey i have a Ibanez TS9DX I’m trying to repair right now. I think i may have found the problem, one of the resistors(203k) is shot. Im new to all of this though and I cant find the part anywhere, any good suggestions for a website to order from?

  4. avatar guitarkitbuilder says:

    There are many sources for resistors but we frequently purchase from Digi-Key at http://www.digikey.com.

    How did you determine that the resistor is shot? Resistors very rarely fail on their own.

  5. avatar conorparnell says:

    I’m not sure it’s the resistor but I don’t know what else it would be, still trying to figure it out actually. The first thing i did was replace a diode that was obviously broken, and this came before the resistor im talking about. I used a DMM to test around using the TS9 schematic and when I tested the 203k(yellow) resistor it was the only one that didn’t show a reading. Signal is passing through the pedal when it’s switched off but not once it’s switched on.

  6. avatar guitarkitbuilder says:

    Conor, send us a really good photo of the inside circuit board of your pedal, so we can see the resistor and diode you replaced

  7. avatar Marcus says:

    I did a Monte Allums mod on my TS9DX and I can’t get the “Tri-Gain Gain Mod” to work. I’ve tried different switches and components, but I still don’t hear any changes in sound when I click the switch…HELP!!

  8. avatar Jeremy says:

    I’m trying to purchase the three pots for my TS-9 and I’m having a very difficult time. Can you help me? I know they’re Alps 100KB 411G,500KA 402G, and 20KW 349G. I was told the 16mm Knurled by Alphas (from Mouser) work, but I seem to not be able to find anything like that on Mouser. If I enter a few parameters (i.e. Alpha, 100k resist, linear), I loose the others (16mm, knurled). I’m new to this, so I’m probably missing something. Thanks for any help you can provide!

  9. avatar andy says:

    Hey!

    Thanks. Same problem now working : )

  10. avatar nick says:

    You guys are geniuses. If I’d have known this a day or so earlier, I wouldn’t have run out and bought a new-used TS808. Oh well … the more pedals, the merrier, I suppose.

  11. avatar Paul says:

    Hi i have TS9 and it was working properly yesterday. I move the pedal to a different location on my pedal chain. Then suddenly there was no signal on the entire pedal chain. I noticed that when i remove the TS9 from the chain everything works well. However, when i try the TS9 alone there was no sound or signal but power is there because the indicator light was on. Hope you can give me an advise. Thanks.

  12. avatar Eric B. says:

    Hey Guys,
    I was ready to toss my TS9 that I bought in the mid 90’s – as the Drive and Levels were not working. My last ditch effort brought me to your site and after opening the back to find that all three pots were quite crooked…I loosened them up and straightened them out. Worked like a charm. Thank you so much!!!

    Eric B.

  13. avatar Dave says:

    Hi! Mine had a rather unique problem. I could use the footswitch once to turn the effect on, but could not use the pedal to turn it off. Anyway, there is a spring below the metal footswitch that connects it to a very small circuit board with a micro-switch. The spring was mounted in such a way that it would not allow the micro-switch to operate correctly. Easy to adjust if you simply open the TS9 and remove the little circuit board under the footswitch.

  14. avatar David says:

    Hello, I was wondering if it is common for the dry signal to be louder or only as loud as the ts-9 when turned on? Is there any way to fix this? Thanks!

  15. avatar Alex Z says:

    My TS9 has TROUBLE SWITCHING ON or OFF sometimes. I sometimes press harder to make it ‘catch’ but i think just pressing several times also triggers on or off. Is this just a bad switch perhaps? When on or off it seems to work fine. It is just getting the switch to trigger that fails (sometimes).

  16. The input jack on my TS9 tube screamer physically broke. After I had it repaired ( or replaced, I don’t know which ) it doesn’t work as it did before the repair. I always used it with the drive full up and the tone at zero. Since the repair it seems to have ( please excuse the expression as I don’t know of another way to describe it ) no balls. ( no creaminess and less gain ) I’ve always used Batteries. I’ve tried new and different brands of batteries but nothing seems to help.
    I found those settings to work perfectly for my solo parts. ( I play a strat through a fender Vibrolux Reverb amp. What would be the reason for this drastic change and can it be brought to work before the repair
    PS: I brought it to what I thought to be the most reliable repair shop in my area (Prov. R. I.) PLEASE HELP!

  17. avatar John Davis says:

    I have a TS808(w/Keeley mod.)that works ok sort of! The foot switch is the
    problem. It is intermittent on/off when pushed. Seems to be a contact issue under
    the pedal switch. Can you recommend either a fix or a company that sells these
    type switches. I have researched and as yet have not found anyone who has a replacement. Thank you.

  18. avatar Lou DiCanzio says:

    I have a TS9 Tube Screamer. I bought a universal power supply and by mistake put the tip on backwards which reversed the polarity. Obviously it does not work now. I was hoping this pedal had a fuse, but it does not.
    Can someone tell me what component I may have fried?
    thanks,
    Lou

  19. avatar Asher Crane says:

    I have one of the newer TS9 pedals, and when I turn it on its just a constant buzzing. However if I jiggle the power jack the sound will go away for a moment or two, then come raging back. Anyone know what the problem is?

    Thanks,
    Asher

  20. avatar ARJNORO says:

    my ts9 wont work, no sound, the led lights up, switch works and I have checked the in and out plugs and nothing. help

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