Zonk Machine - middle transistor is silicon ??? trim pot

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Zonk Machine - middle transistor is silicon ??? trim pot

Postby toby2 » 22 May 2019, 03:55

Has anyone seen this version of Zonk before ? The middle transistor is silicon which has a trim pot connected to it .
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 17 Jun 2019, 20:31

Yes. I actually have an identical one in the shop for repair right now. It arrived over the winter, but I haven't had the time to take a look at it yet as I have wait lists for all of our regular builds, which is how I pay the bills and feed my family. It's only the second Zonk like this I've ever seen and it looks ~identical to yours. Yours is the third I've seen, assuming it's not the same one I've seen prior.

There is no schematic out there for this version, so I will trace the circuit when I repair it. I'd like to do a youtube video on it as well, as there isn't any info available on these extremely rare models. The pedal was actually shipped to me from an tube amp builder in Texas who's had it for a year and was unable to repair it. The guy is very knowledgeable and definitely not a hack. He was just at a loss because there is no schematic or info. Doyle Bramhall's pedal board tech recommended me and that's how I ended up with it. I'll try to change the zero info situation when I have time. I suppose I can trace the circuit real quick tonight after dinner if you're curious and don't mind my chicken scratch. Let me know.

Best,

Jon

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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby tonyharker » 18 Jun 2019, 09:33

How do you know its a silicon transistor? Germaniums were available in plastic packages like this - I have some. What is the type number?
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby nightraven » 18 Jun 2019, 10:40

These 'hybrid' Zonks have 2N4061's. Same part can be found in other Hornby boxes from the time. Including this one, I've got photos of 7 surviving 'hybrid' Zonks so far. Date codes on the pots in these pedals places them at 1968 at the earliest.
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 18 Jun 2019, 14:31

Night raven is exactly correct with the 2N4061. I've personally only seen two of these beasts, but there are some photos floating around the internet. I have been unable to confirm if they are of the same pedal(s). I haven't pulled the pots and looked at date codes yet. I have to do repairs in the odd hours when I'm not taking care of the regular Acid Fuzz stuff.

I did trace this one out last night and found the problem with it in the process. I'll try to get it under the soldering iron later in the month & do a demo of it. I'm assuming it's going to be more stable with temperature changes having the Si tranny in there? If it is, and I dig the sound I'm thinking I may offer this hybrid transistor combo in our Zoink builds as the whole point of the Zoink was to be pedal board friendly for live use. Curious to hear what it sounds like when I fire it up.

It would be cool to get an accurate list of survivors going! Maybe we can get the ball rolling here on freestompboxes and other owners/stewards of these will chime in?
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 18 Jun 2019, 19:12

There's a fun article on the Zonk here: https://www.vintageguitar.com/23068/hor ... -machines/

"Skewes translated that cultural shift into a business; with his wife, Madge, he founded his own musical-instrument company in ’65, from his home in Garforth, in West Yorkshire – far from swinging London. Among his first products was a fuzz pedal." I think it's cute that JHS started out just his wife and him working from home. Reminds me of the Acid Fuzz thing.

"To design and build his stompboxes, Skewes commissioned a small firm called Wilsic Electronics, in the village of the same name near Doncaster. Owner Charlie Ramskirr set to work."

“Charlie designed the pedals, and I guess he cribbed circuit ideas from others, though I do not know whether from the Tone Bender,” Skewes remembers.


I'm gonna take a wild guess and assume that whoever was building the Zonks got fed up with tuning the all germanium transistor set and the hybrids were an in between stage before the Zonk II? I pulled the pots, but no date codes. If there are photos of others with pots dating to 1968, I assume these were the final version of the Zonk before they moved on to the Zonk II?

This Bad Larry is in the que for repair and I'll try to clean up my office and get a video demo and post pics & the schematic shortly. I think it would be cool to see a thread here documenting this version and I'll do my best to provide as much info as I can. The guy that had it before me is a very talented tube amp builder and actually pulled the 2N4061 and replaced it with an OC71, because he couldn't find any schematic or evidence of this version, so he thought it was an aftermarket repair/mod. I don't blame him. He's a tube amp guy, not a fuzz nerd, and there's ~no info on these. Deductive reasoning illustrates the 2N4061 is original. If anyone has doubts these hybrids were OG from the factory, I ran a curve trace on the 2N4061 and compared it with another 60's production TI 2N4061 and they are ~identical. I did that mainly because the stamp was worn off this 2N4061 and I had to put it under a microscope to see anything. I wanted to be 100% sure about this one. The provenance on this particular pedal is the owner found it for sale in London, CA on a site called kijiji, which is basically a Canadian Craigslist. The wacky thing is that you'd think if one was going to pop up for sale it would be in London, England as they were made in Yorkshire. Anyway, it doesn't make sense that any of the hybrids with 2N4061's are mods, as some have suspected. As NightRaven stated, JHS was already using the TI2N4061 in other pedals. Does the Pope shit in the woods or what?
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby nightraven » 18 Jun 2019, 20:37

acidfuzz wrote:? I pulled the pots, but no date codes. If there are photos of others with pots dating to 1968, I assume these were the final version of the Zonk before they moved on to the Zonk II?

Possibly. The turret board version of the Zonk is pretty late too.

The guy that had it before me is a very talented tube amp builder and actually pulled the 2N4061 and replaced it with an OC71, because he couldn't find any schematic or evidence of this version, so he thought it was an aftermarket repair/mod. I don't blame him.

Ergh, you sure he's not a hack? :shock: Was it ProAnalog 'Scotty'? He's got a reputation now for pulling silicon transistors from unusual fuzz pedals and replacing them with germanium parts because of tEh mOjOz. Makes for a good case to put information about this version out there, because it's not the first hybrid Zonk that's been butchered:
3362947863_b134176fe2_b.jpg


The provenance on this particular pedal is the owner found it for sale in London, CA on a site called kijiji, which is basically a Canadian Craigslist. The wacky thing is that you'd think if one was going to pop up for sale it would be in London, England as they were made in Yorkshire. Anyway, it doesn't make sense that any of the hybrids with 2N4061's are mods, as some have suspected. As NightRaven stated, JHS was already using the TI2N4061 in other pedals. Does the Pope shit in the woods or what?

Canada is not at all wacky. Zonks overwhelmingly turn up there, rather than in the UK. It seems that Hornby Skewes had a big distribution thing set up there.
Kijiji, eh? Is this the one on your bench?
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby Electric Warrior » 18 Jun 2019, 20:58

nightraven wrote:
acidfuzz wrote:?

The guy that had it before me is a very talented tube amp builder and actually pulled the 2N4061 and replaced it with an OC71, because he couldn't find any schematic or evidence of this version, so he thought it was an aftermarket repair/mod. I don't blame him.

Ergh, you sure he's not a hack? :shock: Was it ProAnalog 'Scotty'? He's got a reputation now for pulling silicon transistors from unusual fuzz pedals and replacing them with germanium parts because of tEh mOjOz. Makes for a good case to put information about this version out there, because it's not the first hybrid Zonk that's been butchered:
3362947863_b134176fe2_b.jpg



That happens quite often. Some actual vintage parts get replaced when someone thinks they don't look old enough. :(
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 19 Jun 2019, 17:06

I don't have the pedal on my desk right now, but I'll check it against the photo night raven posted. No, not Scotty "Pro" Analog. Incidentally, I was actually accused of BEING Scotty/Proanalog when I first started doing the Acid Fuzz thing around 2009 or so. I was selling on Ebay a lot then and people were emailing me saying they know I'm Scotty and I owe them money!!!???? :slap:

I would not say he's a "hack". I don't bring my FIAT to a FORD mechanic. The guy who had it before me is an old friend of the owner from Texas, Paul Sanchez at Red Iron Amps. He had it for a year, but couldn't find any info on it and assumed the 2N4061 was a replacement. I don't want to talk shit on anyone here guys, lets check our egos and all agree to stick to the facts on documenting these Zonks. This dude Paul got it non-working and is NOT a pedal nerd. He builds tube awesome amps and I assume he was just offering to help out a friend and didn't have much invested in the project. That's when Dave Phillips at LA Sound Design hipped him to me. "From each according to his ability, to each according to his needs." I used to get that kinda shit all the time in LA. My friend Christian Bland once dropped off a Binson Echorec at my house that had already been "serviced" twice but never worked. It was the single most fucked up piece of gear I've ever repaired, but what was I gonna do say no? His band is one of my favorites and I wanted to help him and see that old lady being used to make awesome music. So,I told him "I'll get to it eventually" and stuck in in my attic until I had time to sort it out. I honestly did the same with this Zonk. It arrived over the winter and Kristina actually originally answered the repair request and said NO, that I don't have time without even TELLING me!?? Acid Fuzz is the only thing I have to pay me way in the world and we have a daughter to support, so it's not as glamorous as some people may imagine. I'm on a build schedule and Kristina keeps me in check. Quick tip for any single builders: don't get married (kidding).

I can't really say I blame the people who pulled the 2N4061's and replaced with germaniums. We don't know what we don't know. Lets make sure the info gets out there and this does not happen again. I'm curious whether of not all of the hybrids have the same exact schematic?

I'll clear off my desk and sort this out today or tomorrow and post what I can. Hopefully over the weekend I can actually do a video demo so y'all can hear it.
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 22 Jun 2019, 03:36

Here's the schematic for this one. Really no different than the all germanium Zonk, aside from the trimmer:

ImageZonk Hybrid Schematic Web by Jonathan Curl, on Flickr

I'll post some photos shortly. I also did an overview of the repair and a demo of what it sounds like. It's a bitchin' fuzz for sure :horsey: . I'll try to edit that and get it uploaded to youtube over the weekend so you can hear it.

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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 22 Jun 2019, 03:43

Please note, that's actually the wrong file. That's the trace I did before I repaired it. The 47 ohm output resistor is WRONG. It's what was in this when I got it, and there's no way in hell that it is stock. The out put level was insane with only 47ohms to tame it back. I replaced it with a 2.2 Meg and it's still a LOUD pedal, like all Zonks.
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby Manfred » 22 Jun 2019, 06:16

acidfuzz wrote:Please note, that's actually the wrong file. That's the trace I did before I repaired it. The 47 ohm output resistor is WRONG. It's what was in this when I got it, and there's no way in hell that it is stock. The out put level was insane with only 47ohms to tame it back. I replaced it with a 2.2 Meg and it's still a LOUD pedal, like all Zonks.


Have you read the voltages on the transitor pins?
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 22 Jun 2019, 15:58

Yes, I did note the voltages at 1/2 "SWELL" and at full "SWELL". I did a video overview of the repair. I'd gladly post it here but freestompboxes doesn't seem to like youtube links, even with the youtube tag button. Anyone else have this problem?
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby Cub » 22 Jun 2019, 17:20

acidfuzz wrote:I did a video overview of the repair. I'd gladly post it here but freestompboxes doesn't seem to like youtube links, even with the youtube tag button.

Remove the "s" from "https" in the addy and she'll be alright.


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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 23 Jun 2019, 02:12

Thanks Cub! I tried that, but maybe I was just confused because the video wouldn't load when previewed?

[youtube]http://youtu.be/q9I5HRkP13Q[/youtube]
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 23 Jun 2019, 02:14


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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 23 Jun 2019, 04:11

Here's what it sounds like:

Link
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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby Manfred » 23 Jun 2019, 15:27

Thanks for sharing all the details of the mods.

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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 23 Jun 2019, 17:46

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Re: Zonk Machine - middle transistor is silicon ??? trim pot

Postby acidfuzz » 23 Jun 2019, 17:57

Here are the voltages at ~70°F with a 9V battery:

1/2 "FUZZ" Full "FUZZ"

Q1: C -8.98V -8.95V
B -.707V -.715V
E -.656V -.676V

Q2: B -.643V -.672V
C -7.16V -3.632V
E -0.1mV -0.1mV

Q3: C -7.99V -7.51V
B -51.7mV -51mV
E -0.1mV -0.1mV

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