Ibanez TS808 footswitch repair

[Hemmel]

Hi guys.

I'd appreciate your advice on this.
My nephew has a TS808 that looks like this one:


We tested it together and the footswitch doesn't work properly. Sometimes we need to press it 3 or 4 times for it to activate or deactivate the effect.
So I offered to replace the footswitch with a 3pdt, mainly because it's all I have, and I'd try to change it to a true bypass.
The goal is NOT to have a true bypass, it would be a "nice to have", but isn't necessary. As I said, the only reason I'm putting a 3pdt switch is because it's the only footswitch model I have in stock right now.

Inside of pedal looks very much like this:


The current footswitch has only 2 wires, one going to connector #2 (on the picture, the 2nd from right, green wire) and another wire going to ground on output jack.

So this is what I thought of doing:


Advice? Questions? Comments?
Thanks!

[bluebunny]

Have you confirmed first that it's the switch that's at fault?  It should be making a reliable short across its lugs each time you press it.

[Hemmel]

I will double-check tonight.
During first test, after removing the switch from the circuit, both wires had continuity.
After pressing it, continuity was still there, and I had to press it hard, 3 times, before continuity broke.

Will reply tonight after more tests.

[bluebunny]

So the two wires that go to the switch are connected somehow, even without the switch connected to them?  Sounds like something amiss in the flip-flop circuitry.   

[Hemmel]

Actually, no.
I unsoldered the wires from the circuit board, not from the switch.

However, your reply has made me think that perhaps there is a bypass switching on the circuit board itself.
I'll have to find which version of the 808 this is, and find proper schematics.

[bluebunny]

I'm pretty sure that they're all the same (from a switching point of view).  But go to GeoFEX and check out the "Technology of the Tube Screamer".  Either way, yes, the switching is on the board: a couple of transistors and some associated passives.

[Hemmel]

Thank for the link, Marc.... so after reading I realize it's a momentary switch, not an on-off switch like I thought it was.
This changes everything...

Also, after reading this post I think a simple squirt of contact cleaner might do the trick.
I might have a small momentary switch laying around somewhere, I could use it to determine if the switching circuit is functional...

[bluebunny]

I might have a small momentary switch laying around somewhere, I could use it to determine if the switching circuit is functional...

You could test it simply by shorting across the switch lugs with a handy screwdriver or paper-clip or ...

[Les Turnbull]

Dont no if the 808 is similar to the TS9 but i replaced the spring under the foot switch on my TS9 and it now works 99% of the time though the TS9 are well known for there poor footswitching . The TS808 is back in production so a email to Ibanez may source a new switch .

[Hemmel]

Coming back to this... my nephew says he'd very much like a 3pdt stomp switch, mainly because all of his pedals have them, and that he's not used to the small switch on the 808.
Okay.

I found this guide:
https://web.archive.org/web/20120804013546/http://www.jackdeville.com/jackdeville/manuals/click-less_ibanez_ts808_install_manual.pdf

It seems quite straight-forward but it talks about having a "Click-Less True-Bypass PCB", which I obviously don't have.
So, I figured I'll simply use the 3pdt wiring scheme I'm used to, but then I'm a bit hesitant on a few things:
- Do I still remove the 56K resistor as suggested on page 3? I'm guessing it'll cut the JFET-switching part of the circuit, right?
- Looking at pages 6 and 7 I'm pretty sure I understand where to connect the 3pdt lugs but then on page 7 it talks about Switch 1 and 2 wires". I'm not sure what to do with them. Short them? Remove them?

Thanks again

EDIT: Okay. I found that the 56K resistor needs to be removed so that the JFET-switching circuit stays on "effect ON" mode, by preventing one of the JFETs from getting voltage. Got it.

[Govmnt_Lacky]

Keep in mind that most likely, the momentary flip-flop switching also controls power to the On/Off LED. Getting TB for the audio may just be as simple as removing and jumpering past a JFET (Q102?) but getting the LED to respond correctly may require replacement and wiring (with a CLR) to the new 3PDT switch.

[Hemmel]

Good call, G_L... hadn't thought of that...

>> Getting TB for the audio may just be as simple as removing and jumpering past a JFET (Q102?) but getting the LED to respond correctly may require replacement and wiring (with a CLR) to the new 3PDT switch.

TB?
Tuberculosis?

CLR?


Sorry, I'm not sure what those acronyms mean...

[Govmnt_Lacky]

TB?

CLR?

Sorry, I'm not sure what those acronyms mean...

TB = True Bypass

CLR = Current Limiting Resistor

[Hemmel]

TB = True Bypass

CLR = Current Limiting Resistor

Yep. I feel stupid. Those were pretty obvious.

Well, I lifted the 56K, removed the old switch.

I'm going to try putting a 2K2 between the "LED-" wire and a lug of the 3pdt, just like most true-bypass (or TB ) wiring.
Unfortunately, I've misplaced those 3pdt, so it'll have to go to tomorrow.

[thermionix]

I just did a 3PDT true bypass mod on a TS808 for a customer.  Just hours ago.  I was my first time and I had to figure it out with the factory schematic and layout.  But I nailed it and it works perfectly.  I can probably be of some help, it's all very fresh in my mind.

The LED part is easy.  Leave the two wires, red and pink, going to the LED daughter board.  The red wire is the +9v, and the pink goes to the CLR on the main board.  On the other side of the CLR is a zener diode, right near the middle of the main board.  Remove that zener diode.  In the hole where the cathode had been, add a wire, maybe 4 inches long.  That goes to the new footswitch to get connected to ground when the pedal is engaged.

I recommend wiring the new 3PDT to ground the input during bypass.  You can avoid switch pops without adding a pulldown.

[Hemmel]

I can probably be of some help, it's all very fresh in my mind.

Thank you for offering.
I'll try out what you said tonight and keep you posted.

[thermionix]

I grabbed these two images off a .pdf version of the original Ibanez service manual.  Tried to clean them up a bit.  The reissues are built exactly the same, came in very handy for me.

[Hemmel]

It's hard to get free time to work on this.
Tonight, this is what I will attempt:



Fingers crossed!

[thermionix]

I also removed Q104, Q102 (replaced by jumper), R127, R117, R121, and C111.

I think your footswitch plan will work fine.

[Hemmel]

Well, yesterday I only had time to solder the jumpers on the 3pdt switch (pins 1-6 and 3-9).
I hope I wont be interrupted tonight.

Thermionix, can I ask why you removed all of those parts?