Dr. Scientist Woofer Wailer

[Alex]

This was a request but I didn't add it to the main page cause at the end it's just another Tube Screamer's copy with a couple of switches.

[MatSmith]

Alex. Thank you SO SO SO SO SO MUCH.I borrowed one of these from my work buddy and fell in love with it. Been gassing hard for one since.The building starts this weekend :D!

[Alex]

You are welcome!
The LED is a transparent/red one.
It should be good to go but double check the layout against the schematic first.
Let me know if it works!

[MatSmith]

Hey Alex. Built this over the last few days. Still waiting for a 500k pot but couldn't wait so put a 470k in to test with.

Here's the image.



When I turn the effect on I get nothing. No sound at all.

I took voltages down in the hope someone somewhere has voltages for a tube screamer.

IC 1- 4.6v
IC 2- 6.5v
IC 3- 4.5v
IC 4- 0v
IC 5- 4.6v
IC 6- 4.6v
IC 7- 4.6v
IC 8- 9v

T1 E- 3.6v
T1 B- 3.9v
T1 C-  9v

T2 E- 2.5v
T2 B- 3v
T2 C- 9v

Do these sound correct? The only changes I've made to the layout you created for me is I've added a 2nd 4.7k ohm resistor off the 9v rail for a 2nd LED (you can see it right in the bottom left corner of the photo) and I had to use 2x10k resistors in parallel to make the 5k.

I'm confident that the soldering under the board is fine with no jumpers or anything weird like that.

Any clues?

[Alex]

Hi Mat.
Volume is not connected because there is a 1uF cap missing:
Vol 3 -> 1K Res -> 1uF Cap -> IC pin 7
Let me know if it works.

[Ciaran Haslett]

Hi Matt

Pin 2 on the IC is high.  Should be around vref (4.5V).  Q1 emitter voltage seems a bit high too.  You would usually expect one diode voltage drop (0.7ish V) between the Base and Emitter....just like your Q2.  I'd have a look around those two areas for any solder bridges/misplaced or wrong value components etc.  It's very hard to make much of anything with your pic as a lot of joints are obscured by the caps/transistors/massive resistors etc.

Good luck

[Ciaran Haslett]

haha.....there's that too

[MatSmith]

Alex:

OOOOOOPS! How the hell did I miss that? Momentary lapse of concentration. Haha

Anyway, 1u cap is in now and when I turn on the effect I get noise. It's just a tone, like a never ending beep that I can make louder or change it's note by playing with the controls.

Ciaran:

Just realised I was using the PSU that came with my EHX Soulfood which is 9.6v. Voltages with my powerbank 9v PSU are:

IC 1- 5.1v
IC 2- 5v
IC 3- 4.9v
IC 4- 0v
IC 5- 5.1v
IC 6- 5.1v
IC 7- 5.1v
IC 8- 9v

Q1 E- 3.9v
Q1 B- 4.2v
Q1 C-  9v

Q2 E- 2.6v
Q2 B- 3v
Q2 C- 9v

[Alex]

There is a problem somewhere in your circuit.
Wiring, bridges, cuts, components..
As Ciaran said, you need to take more detailed pictures.

[MatSmith]

Hi guys.

Had to wait for my day off work to troubleshoot the board some more.

I've just gone over the whole vero layout from top to bottom measuring all the components I can and making sure with a continuity checker they all connect to the correct places with no shorts or links or anything. The only things that are a little odd (to me) is 2 or 3 of the resistors seem to take a while to count up to their value on my multimeter and I replaced the 1m resistor with another one as I was getting a weird reading, but now this one reads the same as the last one so I assume it's ok.





Here's the top and bottom of the board. I realise the underside picture is a bit blurry but it does show my soldering is good, no links.

I'm still just getting this squeal when I try to use the pedal.

Anything else I can check. Sorry to be a pain!

[MatSmith]

Links to the pictures so they aren't cut off:

http://guitar-fx-layouts.42897.x6.nabble.com/file/n31484/P1000241.jpg;cid=1464798995166-824

http://guitar-fx-layouts.42897.x6.nabble.com/file/n31484/P1000240.jpg;cid=1464798995166-824

[Alex]

One of the picture is out of focus.
Have you tried to re-flow the solder?

[MatSmith]

I haven't tried to reflow but I've been over the whole board with my continuity tester and everything is making a good connection.

Could it be something as simple as a faulty transistor or IC?

[Alex]

Hey Mat!
Have you tried swapping IC and transistors?

[MatSmith]

Hey Alex.

Thought you'd forgotten about me.

I've changed the IC but not the trannys (as I've run out).

Waiting for pay day so I can order some more (yes, I'm THAT broke).

[Hozy31]

I built this a while ago and put it to one side as i had ran out of 10k resisitors so finished up today and mine works fine. Used 5088s instead of 5089s as it just sounded a bit better with 5088s. I must admit that it didn't work at all when i first built it, eventually discovered that i had an incomplete solder at the base of the first 5088. Thanks Alex.

[MatSmith]

Hi Hozy.

Do you have a picture of your board? Perhaps I can compare?

Thanks for the feedback. I should be able to get some 5088 a bit easier, so I'll try a couple of those.

[Hozy31]

Here you go. Hope it helps. I use polybox caps as i prefer them. The diode is a KD521A, socketed so i could mess with other options. You might spot how anal i am about having all the resistors facing the same direction as well as the caps. I am thinking more and more I may have an OCD.