Dr Boogie need help debugging

[0ron124]

Hi all,

So just recently decided to start a new project while I still have time before summer break is over. This is my second pedal build now (not including mods) so I'm still pretty new at this whole thing. Anyways the problem is below any help would be greatly appreciated.

Here is the checklist to fill out:
1.What does it do, not do, and sound like?
2.Name of the circuit =
3.Source of the circuit (URL of schematic or project) =
4.Any modifications to the circuit? Y or N
5.Any parts substitutions? If yes, list them.
6.Positive ground to negative ground conversion? Y or N
7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? =>
Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:
Voltage at the circuit board end of the red battery lead =
Voltage at the circuit board end of the black battery lead =

Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:


1. It turns on (LED lights up), there is sound when bypassed, also when the strings are strummed fairly hard a muddy/bladdy distortion sound is heard.
2. Boogey 57 (Dr Boogie)
3. Guitarpcb.com here's a direct link to the PDF build document.
4. No mods
5. No subs.
6. Umm not sure
7. Not relevant due to a AC adapter that is being used. The voltage is 9.05v.
Note: I am not sure how accurate the pinouts are on the 2N5457's I used this link to determine what they are http://thedatastream.4hv.org/images/prm_pre_amp/bc182_pinout.png
Q1:
   C: 6.0v
   B: 0.624v
   E: 0v
Q2:
   C: 6.0v
   B: 0.460v
   E: 0v
Q3:
   C: 6.0v
   B: 0.506v
   E: 0v
Q4:
   C: 6.0v
   B: 0.433v
   E: 0v
Q5:
   C: 8.96v
   B: 1.589v
   E: 0.6v
D1:
   A: 0v
   K: 9.05v
D2:
   A: 0v
   K: 2.5v

[Brymus]

2N5457 are FET's
Drain Gate Source not Collector Base Emitter
You need to switch pins 2 and 3 on all your FETs and try again.
That should get you sorted once you bias them to about half of your supply (9V) so around 4.5V
Google 2N5457 and download data sheet.

[deadastronaut]

http://thedatastream.4hv.org/images/prm_pre_amp/2N5457_pinout.png

[0ron124]

Awesome got it running! Turns out I just biased the JFet's wrong. Divide each of the required voltages by 10 and that's what I had them at. Totally silly on my part.

Anyways, I do have an issue with the bass knob. When turning it there is no change in tone whatsoever. It literally doesn't make a difference. Could it be a bad pot? I am going to pull some voltages tonight and go from there or should I just start tracing the bass circuit?

[deadastronaut]

wow that was in july you started that...

anyway great!..ive had issues with the bass pot on some boogie builds too...double check those connections, especially on the pot itself...dry joint etc..

[0ron124]

Yeah, I've been super busy with school and work and finally made time to work on it. I'll do a trace tonight and let ya all know how it turns out.

Thanks