madbeanpedals::forum

Projects => General Questions => Topic started by: kdmr on March 21, 2018, 12:38:23 AM

Title: SANITY CHECK: CB30 clone
Post by: kdmr on March 21, 2018, 12:38:23 AM
cloning a CB30 and I've built a few in the past but damned if this thing isn't getting under my skin. I want to believe i've got shoddy transistors but I can't find my documented working voltages. Losing signal strength at the Q1D/Q2S junction. The circuit passes signal through but i know what its supposed to sound like and this aint it. 2N5457, 12v Meanwell switching supply.
Pin voltages (DSG):
Q1: 8.08 / 2.28 / 0
Q2: 12 / 8.08 / 4.09
Q3: 7.91 / 2.34 / 0
Q4: 12 / 7.91 / 4.05
Q5: 12 / 9.58 / 2.88

Obviously the drains on Q1/Q3 are well above the target, but I'm assuming this is due to running at 12v which I haven't had issues with in the past. Running at 9v gives about 6v on the Q1/Q3 drains. Anyone have working voltages that I can use to cross reference?
Title: Re: SANITY CHECK: CB30 clone
Post by: stringsthings on March 25, 2018, 04:40:08 PM
Quote from: kdmr on March 21, 2018, 12:38:23 AM

Q5: 12 / 9.58 / 2.88


I believe that Q5 is set up as a buffer and that the voltage on the gate should be close to 1/2 * supply voltage.
Closer to 6.0V for a 12.0V supply voltage.  If someone knows more, please chime in.