Debug help General Guitar Gadget Ibanez Tube Screamer First Build

[Phoenix60]

Hi everyone,  first build here and I'm testing the board  outside of the box before I  connect the switches.  I'm getting sound through my amp, but it's clean sound, no distortion.   I did have diode 5 in backwards, and the battery heated up in an earlier test.  I've since removed it and no more overheating.  It's the diode that protects against reverse polarization. Anyway,  that's where I'm at, hoping you can help me.   Here are the particulars:

Pedal schematic and diagram: http://www.generalguitargadgets.com/effects-projects/distortion/tube-screamer/

Battery 8.28v
IC
1 4.13v
2 4.23v
3 4.13v
4 0v
5 4.13v
6 4.13v
7 4.13v
8 8.28v

Q1
C 8.28v
B 3.02v
E 3.03v

Q2
C 8.28v
B 3.45v
E 3.0.v

[bartimaeus]

you haven't yet added the switch to choose which clipping diodes are used. without the switch, no diodes are connected, so you get no clipping. if you don't want the switch, you need to jumper C1 and C2, as explained here: http://www.generalguitargadgets.com/pdf/ggg_its8_lo_no_clipper_sw.pdf

also, it's non-essential but i'd trim some those leads a bit more, them being that long makes them more likely to cause accidental shorts.

[11-90-an]

yep what ^^he said. also i'm gonna emphasize on the clipping of component leads... can short out +9v and GND, in some cases.

also, welcome to the forum..

[Phoenix60]

I will make a jumper to test and trim the leads, thanks!

[duck_arse]

also welcome, and it looks like you have a short between b and e of Q1. measure the resistance between those two pins.

[Phoenix60]

Hi, it's showing. 532 between base and emitter on Q1.

[antonis]

Hi, it's showing. 532 between base and emitter on Q1.

How come then..??

Q1
B 3.02v
E 3.03v

[Phoenix60]

I don't know how to answer that - I can recheck it tonight.

[willienillie]

Meter loading?  Both bases are fed Vref via 510K.

[Phoenix60]

So I rechecked, and Q1 base is 3.46v.  Something still wrong though, I jumped the switch, and getting a pretty strong buzz through the amp and the guitar signal is barely there, and what I hear sounds more like what I think of as a phase effect, than a crunch distortion.

[Phoenix60]

I will bump my own thread here.  Turns out I was using a bad cord, so the tone is sounding strong through the amp now and the buzzing has lessened considerably.   The tone is sounding fuzzier than I expected.   Any way to fix thst?

Thanks

[antonis]

The tone is sounding fuzzier than I expected.   Any way to fix thst?

Lower Drive pot (R19) value or raise R6 (4k7) value..
Of course, C4 (51pF) or C3 (47nF) value should be altered respectively if you wish to maintain initial LPF (0.159/R19*C4) or HPF (0.159/R6*C3) corner frequencies..

[Phoenix60]

Thanks, I'll give it a try