Problems with Woodpecker Tremolo build.

[Stephenthegun]

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.

 

[Stephenthegun]

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?

 

[xefned]

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!

 

[Stephenthegun]

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.

 

[Popnfreshbass]

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.

 

[Stephenthegun]

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.

 

[Popnfreshbass]

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

 

[Popnfreshbass]

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

 

[Stephenthegun]

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.

 

[Mcknib]

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

 

[Stephenthegun]

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

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.

 

[Mcknib]

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!

 

[Stephenthegun]

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!

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?

 

[Mcknib]

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

 

[Stephenthegun]

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

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.

 

[Mcknib]

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

 

[Stephenthegun]

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

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!