# Problems with Woodpecker Tremolo build.



## Stephenthegun (Jul 9, 2021)

I am at a bit of a loss as to what is going on with my build. I am a total newbie, this is my second build, and am still trying to understand how to read a schematic let alone know what I have done wrong. Many thanks!

The pedal allows sound through when off. When on, sound continues to be produced but it does not do the tremolo thing. Instead, the depth knob (B10k) when turned down increases the volume and when turned up it gets quieter. The B100k volume pot works like it should, increasing and decreasing the volume as well. The rate pot and switch do not seem to be doing anything. I did decide to add an expression input for the rate, but I think I have it wired correctly. If someone could please help me that would be great. I will attach pics.


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## Coda (Jul 9, 2021)

How do you have the expression jack wires? Just curious…


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## Stephenthegun (Jul 9, 2021)

Coda said:


> How do you have the expression jack wires? Just curious…


I will check when I get home, but I used the wiring diagram from the pedalpcb wiki page as a template. If you are looking at the gut shot photo the pot is wired to the lower lugs and the pcb is wired to the top lugs.


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## Stephenthegun (Jul 9, 2021)

Stephenthegun said:


> I will check when I get home, but I used the wiring diagram from the pedalpcb wiki page as a template. If you are looking at the gut shot photo the pot is wired to the lower lugs and the pcb is wired to the top lugs.


I have checked the jacks and, as best as I can tell, they are wired like the expression control diagram. https://wiki.pedalpcb.com/wiki/Expression_Control_Wiring


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## Popnfreshbass (Jul 9, 2021)

Where did youget your 2n6027? I had a fake and mine was doing the same thing.


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## Stephenthegun (Jul 9, 2021)

Popnfreshbass said:


> Where did youget your 2n6027? I had a fake and mine was doing the same thing.


Do you know how to check if it is working? I got it from the website Banzai Music. I have seen on here that some people have gotten fakes from them. How did you end up solving the problem? Did you get one from somewhere else? Unfortunately, I got my 2N5089 and PF5102 from them as well.


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## Popnfreshbass (Jul 10, 2021)

Stephenthegun said:


> Do you know how to check if it is working? I got it from the website Banzai Music. I have seen on here that some people have gotten fakes from them. How did you end up solving the problem? Did you get one from somewhere else? Unfortunately, I got my 2N5089 and PF5102 from them as well.


Banzai was where I got fake/dud. 

I fixed mine by buying a central brand from Mouser.


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## Stephenthegun (Jul 10, 2021)

Popnfreshbass said:


> Banzai was where I got fake/dud.
> 
> I fixed mine by buying a central brand from Mouser.


Thanks, I will have to give that a try and see if it solves the problem. I found your old thread where you had the same problem. I don't see a solder bridge at all so I am not sure why my depth pot is still working as a reverse volume. Also, did you have to pay €20 to ship? I just put it in my cart and it was showing €22.11, yikes.


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## giovanni (Jul 12, 2021)

Your board could use a bit of cleaning and the solder tits could be trimmed shorter. But that wouldn’t explain the issue you are experiencing. Bad transistor could be the root cause. I think there are legit European vendors that won’t charge you that much.


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## Coda (Jul 12, 2021)

giovanni said:


> Your board could use a bit of cleaning and the solder tits…


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## Stephenthegun (Jul 13, 2021)

giovanni said:


> Your board could use a bit of cleaning and the solder tits could be trimmed shorter. But that wouldn’t explain the issue you are experiencing. Bad transistor could be the root cause. I think there are legit European vendors that won’t charge you that much.


I will give the board a clean and clip the tits 😂. What vendors would you recommend? I am new to sourcing parts and got hit with a bunch of customs charges on my Tayda order a while back. This is why I was hoping Banzai would be a good source. Also, in fairness to Banzai, I contacted them about the faulty 2N6027 and they are sending me a new one at no charge.


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## music6000 (Jul 13, 2021)

giovanni said:


> Your board could use a bit of cleaning and the solder tits could be trimmed shorter. But that wouldn’t explain the issue you are experiencing. Bad transistor could be the root cause. I think there are legit European vendors that won’t charge you that much.


I may never look at my Soldering the same way again!!!


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## giovanni (Jul 13, 2021)

I have never purchased components from Europe but I read that https://www.musikding.de/ should be good.


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## giovanni (Jul 13, 2021)

BTW, “tits” is a technical term, believe it or not!


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## Stephenthegun (Aug 2, 2021)

Got my free replacement 2N6027 from Banzai and still the same problem. I am wondering, is there an alternative to the 2N6027 I could source?


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## fig (Aug 2, 2021)

Good News Everyone!

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## Loxton (Aug 2, 2021)

I get my 2n6027 from Smallbear. Yes shipping costs are stupid to Australia. But never had an issue with their items.








						Transistor 2N6027 Programmable Unijunction
					

Small Bear Electronics DIY Parts




					smallbear-electronics.mybigcommerce.com
				




As far as your issue I'm unsure but, understand this. With the Depth control all the way down it turns the tremolo effect completely off. Meaning you can use it as a boost pedal via the volume/level adjustment.

Do you have the same effect with it out of the enclosure and wired correctly with your expression input removed?? I'd start there.


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## Stephenthegun (Aug 5, 2021)

Loxton said:


> I get my 2n6027 from Smallbear. Yes shipping costs are stupid to Australia. But never had an issue with their items.
> 
> 
> 
> ...


I have not unwired the expression input, but I am certain I have that correct. It works the same outside of the enclosure. Thanks for the tip on Smallbear.


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## Stephenthegun (Aug 5, 2021)

I feel I should give a shout out to Banzai. I contacted their customer service about the issue with my 2N6027 and they immediately apologised and sent out a new one. Upon receiving the replacement 2N6027 it was also found to be a fake. I contacted them and had an immediate response and explanation. They explained that they bought their lot in 2015 and had not been made aware that they were not working for some people. He told me they have pulled the old lot from sales and that they have gotten in a new lot from Central Semi. I reported my problem to them yesterday and they have already sent me the replacement. I am really impressed with their willingness to make sure they make this right. They have gone through a lot of effort on a very inexpensive part.


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## Popnfreshbass (Aug 7, 2021)

I’m glad they got it straightened out. The 2n6027 was the only dud it the lot I bought from them. So it’s nice to hear they are correcting.


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## Stephenthegun (Jul 9, 2021)

I am at a bit of a loss as to what is going on with my build. I am a total newbie, this is my second build, and am still trying to understand how to read a schematic let alone know what I have done wrong. Many thanks!

The pedal allows sound through when off. When on, sound continues to be produced but it does not do the tremolo thing. Instead, the depth knob (B10k) when turned down increases the volume and when turned up it gets quieter. The B100k volume pot works like it should, increasing and decreasing the volume as well. The rate pot and switch do not seem to be doing anything. I did decide to add an expression input for the rate, but I think I have it wired correctly. If someone could please help me that would be great. I will attach pics.


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## Stephenthegun (Aug 28, 2021)

I have received the newest 2N6027 from Banzai. As best as I can tell it works as a PUT should, but the pedal is still not working correctly. When the depth pot is all the way down the pedal works as a boost and when all the way up the pedal is off. Does anyone have any ideas?


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## xefned (Sep 4, 2021)

Your soldering looks fine. 

I stumbled upon this looking for a different Woodpecker thread. Having just wired an expression pedal (successfully) to a Woodpecker, it's fresh in mind. Looking at your expression pedal wiring, it seems that plugging in a cable might short all 3 of the rate pot pads.

My reasoning: your green and yellow wires are connected to pads that are continuous through a trace on the PCB. If you plug in a mono jack, the sleeve will bridge yellow to black, and you end up with green, yellow, and black all shorted together.

Of course, that doesn't explain why your depth pot doesn't work. It might be worth getting it working on a test rig first without the expression pedal or stomp switch. Good luck!


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## Stephenthegun (Sep 7, 2021)

Thanks for the suggestions and for sharing that thread. I will be taking out the expression pedal and trying to get it working without it. I am still really baffled as to why I am having this problem as the 2N6027 PUT seems to be a working part as best as I can tell.


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## Popnfreshbass (Sep 7, 2021)

Stephenthegun said:


> Thanks for the suggestions and for sharing that thread. I will be taking out the expression pedal and trying to get it working without it. I am still really baffled as to why I am having this problem as the 2N6027 PUT seems to be a working part as best as I can tell.


 Does the 2n6027 say CEN on it? If it doesn’t I might still be suspect of it. But that could be because thats what was wrong with mine. I will take some readings on mine tonight and post them. We dan compare and see where you’re at.


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## Stephenthegun (Sep 7, 2021)

Popnfreshbass said:


> Does the 2n6027 say CEN on it? If it doesn’t I might still be suspect of it. But that could be because thats what was wrong with mine. I will take some readings on mine tonight and post them. We dan compare and see where you’re at.


It does say CEN. That would be super helpful if you could take those readings. Thanks so much for doing that! When I get home I will take a photo of the 2n6027.


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## Popnfreshbass (Sep 7, 2021)

Stephenthegun said:


> It does say CEN. That would be super helpful if you could take those readings. Thanks so much for doing that! When I get home I will take a photo of the 2n6027.


Should be legit if it says CEN. And no problem! I’ll let ya know what I find


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## Popnfreshbass (Sep 7, 2021)

So I took a few quick measurments on mine. It is workinf and I was having similar problems as you so hope the info helps.

Looking at the component side, mode 3 all knobs 100% left to right. 

2n0627
2.9
3.7
0.5

2n5089
0.0
0.4
0.0

Rate
7.5
7.5
7.5

Depth
0.0
0,0
0.0

Mode 3 All knobs 50%

2n6027
2.8-3.8
3.8
0.1

2n5089
0.0
0.4
0.0

Rate
7.6
5.0
5.0

Depth
0
0
0


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## Stephenthegun (Sep 8, 2021)

Here is a photo of my 2n6027. I took the measurements of my pedal at 100% and here is what they came to...
(component side and left to right)

2n6027
1.4
3.8
.17

2n5089
0
.5
0

Rate
7.5
7.5
7.5

Depth
0
0
0

I am a total electronics beginner to the point of quickly becoming confused at what I assume is basic knowledge. As a complete buffoon when it comes to understanding what all of this means I welcome everyones help (and name calling if you must). Am I right in assuming that there is still something not right with my 2n6027? My right and left pins seems to be much less than yours (2.9 compared to 1.4) (.5 compared to .17). I will also say that the left pin was really bouncing around. There were times where it would show a similar reading to yours and then go back down. Other times it was less than the 1.4 I recorded. It seemed around 1.4 was the most consistent number I could get.


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## Mcknib (Sep 8, 2021)

It's based on the vox repeat percussion when you turn depth all the way down it should act as a clean boost as @Loxton said

You're basically dumping all the modulated / oscillating signal to ground through the depth pot wired as a voltage divider all the resistance will be between lugs 2 and 3 turned CCW sending everything to ground via lug 2 and 1

So all your incoming signal goes through Q1 and boosts it

You don't say if you get tremolo between the 2 pot extremes as you turn it up before it cuts out do you get tremolo through the pot range

Q3 is the oscillator so you would get varying voltages on it on what I think is the anode pin (I don't know much about PUT's)

With no power to the circuit check the resistance on the depth pot turned all the way up you should have little to no resistance between lugs 2 and 3 with most resistance between 2 and 1 all the way down little to no resistance between lugs 1 and 2 with most between 2 and 3 you may not get accurate resistance readings albeit it looks like you should you only want to check resistance does change as you turn the pot


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## Stephenthegun (Sep 9, 2021)

Mcknib said:


> It's based on the vox repeat percussion when you turn depth all the way down it should act as a clean boost as @Loxton said
> 
> You're basically dumping all the modulated / oscillating signal to ground through the depth pot wired as a voltage divider all the resistance will be between lugs 2 and 3 turned CCW sending everything to ground via lug 2 and 1
> 
> ...


This is all really helpful information. Thanks!
I am getting no tremolo effect at all though the anode does seem to be oscillating as you mentioned.

I tested the depth pot and it worked exactly as you said it should.


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## Mcknib (Sep 9, 2021)

You wouldn't get any audio on the oscillator part afaik

I know from making a few vox repeaters at the extreme end of the rate pot with mode set to max speed it just sounds like an oscillating noise well to me anyway

Gotta be somewhere from C2 down, you know the boost part works

Is it the same in all mode positions and do you get varying voltage on the rate pot in fact that's a dumb question if yer 6027 oscillates but I'd check it anyway!


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## Stephenthegun (Sep 9, 2021)

Mcknib said:


> You wouldn't get any audio on the oscillator part afaik
> 
> I know from making a few vox repeaters at the extreme end of the rate pot with mode set to max speed it just sounds like an oscillating noise well to me anyway
> 
> ...


The voltage changes as I move the pot but it is not varying. I re-tested the anode of the 2n6027 and cannot get a consistent reading. Sometimes it wobbles around 2.1 - 2.2v other times there is hardly anything like 17mv and still other times it seems to descend in volts the longer I hold the multimeter probe to it from 2.2 down to almost zero. Does this make any sense at all?


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## Mcknib (Sep 9, 2021)

It sounds like you don't get oscillation modulating the signal which you get through a combination of the PUT, rate pot and R10, C7, 8 and 6 I think in the switch off position

6027 left to right pins would be Anode (1), Gate (2), Cathode (3) for comparison to @Popnfreshbass voltages 

Your Anode pin is the one standing out 

The 'programme' resistors are R6 and 8 I'd try reflowing those and R9 and the 6027 anode solder joint which looks like it may be dry try reflowing that first


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## Stephenthegun (Sep 10, 2021)

Mcknib said:


> It sounds like you don't get oscillation modulating the signal which you get through a combination of the PUT, rate pot and R10, C7, 8 and 6 I think in the switch off position
> 
> 6027 left to right pins would be Anode (1), Gate (2), Cathode (3) for comparison to @Popnfreshbass voltages
> 
> ...


Will resolder the 2n6027 joints. I have it socketed at the moment and will now try actually soldering it in and see if that makes a difference.


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## Mcknib (Sep 10, 2021)

Stephenthegun said:


> Will resolder the 2n6027 joints. I have it socketed at the moment and will now try actually soldering it in and see if that makes a difference.


Keep the socket


Just remove the transistor from the socket and visually inspect the socket solder joints and reflow them

It doesn't look socketed in your pic so all the better it is


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## Stephenthegun (Sep 12, 2021)

Mcknib said:


> Keep the socket
> 
> 
> Just remove the transistor from the socket and visually inspect the socket solder joints and reflow them
> ...


The original pic had the old 2n6027 soldered in. When I removed it I socked the joint in case the next one was fake too (which it was). This third one, I think, is real. 

I will indeed reflow the joints as soon as I get a chance. 

Thanks for your help!


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