Debug

[jonathansuhr]

I'm working on my own pedal design and ran into a strange problem.

I have a working prototype, and so I got some PCBs fabbed and now I'm having some trouble.

Here are the voltages on the working pedal:

Q1:
C: 6.5 V
B: 0.82 V
E: 0.24 V

Q2:
C: 6.89 V
B: 0.6 V
E:  0.01 V

Here are the voltages on the defunct pedal:

Q1:
C: 6.7 V
B: 0.81 V
E: 0.23 V

Q2:
C: 2.19 V
B: 0.65 V
E: 0.03 V

I triple checked part values and they're identical on both pedals. I will go over solder joints to make sure everything is working as it should.

[LucifersTrip]

triple checking won't always help...it's easy to miss the same thing repeated times.

measure the in circuit resistances of each resistor in both circuits and see if they match

[duck_arse]

q2 suggests it has a grounded emitter, yes? so the collector resistor of q2 maybe a good place to look.

[LucifersTrip]

Q2E voltage a little > 0 since R11 is small

[jonathansuhr]

Turns out it was a bum collector resistor.

Never had a resistor that didn't work before. Guess I should've checked the most obvious place first. 

[duck_arse]

ahhh, now that I turn on images for this page, I see there is a circuit posted ........