A pricey used pedal arrived non-functioning - is it a simple fix or a return?

[Delicieuxz]

This is a Tone Bender MK III clone, with some nice vintage transistors in it. And I got it for a really good price. But when I powered it on after receiving it, it made a tk-tk-tk-tk-tk sound while engaged and having some guitar signal run through it, while running on either battery or adapter power. It passes the guitar sound while bypassed, though.

Internally, it looks fine - no sign of damage.

Since I got this for a relatively pretty low price, it'd be a shame to have to return it. But I don't really have the tools or experience to troubleshoot it myself, yet. I'm hoping to get there. Can anyone here identify the cause or severity of the issue?

[idy]

Did you know it is positive ground? Did you use a normal polarity power supply? I see the LED is not working either....
Try battery? Perhaps all is not lost.

[soggybag]

Repair would not be difficult with this type of circuit.

Repairing it might void any return option if you can't get it fixed or if repair requires shelling out for some new Ge Transistors which might cost a little bit.

[Delicieuxz]

Did you know it is positive ground? Did you use a normal polarity power supply? I see the LED is not working either....
Try battery? Perhaps all is not lost.

I already tried it with a battery. And it had the same issue.

The pedal says "tip positive" on it. But, as with all Soul Benders that I've seen, it uses a Boss-style adapter, there is no "tip", but the center and sleeve. Boss adapters are centre-negative, sleeve-positive.

[idy]

Right. Look at the manual, it is center positive, the reverse of the normal boss type plug. "Tip positive" is a slightly careless nomenclature, you are right "center positive" would be preferred

You don't know about positive ground(?), very common with old PNP Ge fuzz face.
Can't daisy chain that pedal
Can't use normal 9v guitar center negative
Quite likely plugging in wrong power has killed the transistors and any residual warranty. That's what it does.

the box says right on it "positive tip" and you decided to find out what would happen if you did the opposite. Now you know! Cheer up, maybe it arrived broken and this mistake didn't matter.
Feel like buying new transistors and doing some soldering?

[Delicieuxz]

Right. Look at the manual, it is center positive, the reverse of the normal boss type plug. "Tip positive" is a slightly careless nomenclature, you are right "center positive" would be preferred

You don't know about positive ground(?), very common with old PNP Ge fuzz face.
Can't daisy chain that pedal
Can't use normal 9v guitar center negative
Quite likely plugging in wrong power has killed the transistors and any residual warranty. That's what it does.

the box says right on it "positive tip" and you decided to find out what would happen if you did the opposite. Now you know! Cheer up, maybe it arrived broken and this mistake didn't matter.
Feel like buying new transistors and doing some soldering?

This pedal didn't come with a box or manual. The chassis, which doesn't identify that it uses an unconventional polarity, is all I had to go on - and I was unaware that there exist pedals which use a Boss style connector that aren't centre-negative. Though, even if it's positive ground, that doesn't necessarily mean it will have a positive centre, according to what I read here:

https://www.thegearpage.net/board/index.php?threads/what-do-i-need-to-power-a-positive-ground-pedal.2079196/post-29185385

I searched up what "positive tip" means on a Boss-style adapter, and didn't find a clarification. Only statements like this: https://www.reddit.com/r/guitarpedals/comments/jlv858/boss_sd1_polarity_is_it_tipnegative_sleevepositive/

"There is no tip on this kind of jack and plug. It's center is the hole which is negative and the outer sleeve is the positive. Hence, center negative, outer positive."


If it's damaged due to reverse polarity, then I will have to get some transistors and replace them. If there is reverse polarity damage, will all 3 transistors be affected, or just the first one in the circuit? And is it possible that capacitors would have taken the damage and failed, leaving the transistors OK? Will testing each transistor with a DMM reveal whether it is still perfectly good?

[idy]

Manual
https://www.fulltone.com/sites/default/files/documents/SB-2%20manual_web_4-16-2014.pdf

So the chassis says tip positive. It is a barrel. No tip, just center. That is called Identifying unconventional polarity.

[alexradium]

there should be a trimmer for biasing,try moving that,people like to mess with things

[idy]

The first thing to try is a proper (reverse, center positive) polarity power supply.

It appears to have a silicon diode attached to one transistor, maybe 1n400? series, maybe schotky?
Benders usually have a germanium diode on the Base of Q3, and its reverse leakage biases that transistor. 
I don't know how a silicon would do the job. The other possibility is it is a polarity protection diode, then a 1n400? would make sense. I would test it first:
power off, diode test on the meter, try both directions. Sometimes polarity protection diodes fry, but 1n400? are pretty robust.
Is it attached to both power rails?
And yes, once you have proper power the bias pot might be worth a wiggle.
Is there another, probably glass encased, germanium diode on the board? I don't see one...

[Delicieuxz]

The diode might pertain only to the SB-2, which is a newer and current-production version of the Fulltone Soul Bender that uses different transistors.

The v1 Soul Bender, which has NKT275 transistors, doesn't appear to have a diode on the circuit board or off it.

I've played with the trimpot, but there's no sound however it's set. And there's also no sound when powering the pedal with a battery.

[ElectricDruid]

I feel for you. The idiot that designed that pedal to use the exact same plug/socket as the near-universal boss power supply, except with the polarity reversed needs taking outside and throwing into a lake! If they think that one badly-phrased message is clear enough, they're a fool. And they didn't even think to add any reverse polarity protection to the circuit, despite having made virtually certain that this pedal would be subjected to reverse voltage. It's so, so stupid. Gagh!

[anotherjim]

I see a hint of a power diode lurking in the shadow of one of the green blobby caps. If it's parallel reverse diode protection (actually the most commonly touted arrangement), it could have failed short circuit which will not be liked by PSU or battery. The ticking could be the PSU repeatedly trying to get going against a short circuit.

[Delicieuxz]

I see a hint of a power diode lurking in the shadow of one of the green blobby caps. If it's parallel reverse diode protection (actually the most commonly touted arrangement), it could have failed short circuit which will not be liked by PSU or battery. The ticking could be the PSU repeatedly trying to get going against a short circuit.

I notice it now.

There a diode in the original circuit, but it doesn't look like it's protecting things. It looks like it's what idy mentioned: "Benders usually have a germanium diode on the Base of Q3, and its reverse leakage biases that transistor."

[ElectricDruid]

I see a hint of a power diode lurking in the shadow of one of the green blobby caps. If it's parallel reverse diode protection (actually the most commonly touted arrangement), it could have failed short circuit which will not be liked by PSU or battery. The ticking could be the PSU repeatedly trying to get going against a short circuit.

If that were true, it would be a blessing.

[duck_arse]

when I look at your photos, I see a glass-bodied diode, which suggests germanium. jambed up close to a transistor like that also suggests the biasing diode found in the benders. why not use your meter and probe the connections for connectivity, work out just that diode/transistor even. and when connected to just a battery, what voltages do you read around the circuit? and we expect them all to show the minus sign in front - black lead goes to ground.

[danfrank]

I'd return it if I were the OP... Yeah you got a good deal on it but chances are if there's no protection diode in there, the transistor(s) are fried when you hooked up the wrong power supply. It's one thing to get a good deal on something that's working but really not worth it if the item is a P.O.S. I'm not blaming you, anyone could have made that mistake with the crap "instructions " that came with the unit. Your time is worth money... How much time are you going to have to use to get the unit working again?

But then again, it would be a great opportunity to learn about pedal electronics...

[Ben N]

I feel for you. The idiot that designed that pedal to use the exact same plug/socket as the near-universal boss power supply, except with the polarity reversed needs taking outside and throwing into a lake! If they think that one badly-phrased message is clear enough, they're a fool. And they didn't even think to add any reverse polarity protection to the circuit, despite having made virtually certain that this pedal would be subjected to reverse voltage. It's so, so stupid. Gagh!

Gee, I wonder who that idiot might be? 🤔

[GibsonGM]

I'd never accept that back for a return.  Betcha it was 'really working' when it arrived. It's marked. You can debate whether it was marked CLEARLY or INTELLIGENTLY,  but it WAS marked, and the manual states:

"DC Power Options WARNING! You may only power this pedal with a 9 volt battery OR our Fulltone FPS-2, NO EXCEPTONS. Germanium Transistors require that you use a center-pin POSITIVE 9 volt powersupply, therefore you cannot use a standard
Boss, Ibanez, or even a Fulltone FPS-1 with Center-Pin/ Negative...only use a Fulltone FPS-2 or a Voodoo Labs PedalPower with
their REVERSED cable!"   

Done deal, OP did not read the documentation regarding how to use the product properly.  It was not 'certain' that a reversed voltage would be applied - there are millions of wall warts in the world, and people constantly mis-match them. They called for THEIR wart, if the manual had been read.

It's like putting the wrong fuel in a car - it's in the manual, and a label on the gas cap MAY clue you in. Your responsibility, sadly.   Just obtain and install new transistors and electros, and learn from it.   Fire them off a nasty email to ask them to change the label, too.  Sinceyou bought it used , you're on your own (unless you revert to telling tall tales).  Not up to the reseller to re-mark something etc.

[ElectricDruid]

I feel for you. The idiot that designed that pedal to use the exact same plug/socket as the near-universal boss power supply, except with the polarity reversed needs taking outside and throwing into a lake! If they think that one badly-phrased message is clear enough, they're a fool. And they didn't even think to add any reverse polarity protection to the circuit, despite having made virtually certain that this pedal would be subjected to reverse voltage. It's so, so stupid. Gagh!

Gee, I wonder who that idiot might be? 🤔

Sorry, do we know? Not trying to offend anyone here, but if there's something there that *isn't* true, I'm quite willing to retract what I've said. I don't mean to come across like a d!ck, but it seems to me that there's several bad design decisions lined up in a row there.

Boss centre-negative 2.1mm power has been a standard since the 1980's. Since the 90's it's been widely adopted by everyone else too. If you stick a 2.1mm socket on a pedal in the 2020's, you *absolutely have to* expect that someone will put a Boss centre-negative power supply into it. If that isn't what your pedal requires, protect your pedal against that eventuality, because sooner or later it *is* going to happen. A much better idea would be to use *some other* power connection to emphasise the fact that this pedal uses non-standard power. Like Gibson says about the gas cap to stop you putting wrong fuel in the car,  the Diesel nozzle is a different size from the gasoline/petrol so you literally can't put diesel in your petrol car. That's a way better clue than a bit of unclear text on the enclosure. We want: "Oh! Plug doesn't fit! Wonder why not?!?"

2 cents,
Tom

[Processaurus]

The clever way to power those unusual positive ground vintage fuzzes for todays boards and 9v conventions is to make a -9v supply from a charge pump IC like LT1054. Shocked by the bad decisions with the power supply jack on this one. And no series reverse polarity protection diode? Ridiculous.