Build Your Own Clone Message Board

Hoping someone can help me here. As a pretext: This is my 5th B.Y.O.C. build. I was very careful with this one, taking my time, checked all the semiconductors before installing ( except IC), etc.

The issue is that when I have the RATIO on full compression, the SUSTAIN also has to be full clock-wise to get any sound out. If I move the SUSTAIN counter-clockwise at all from full on, the output volume drops to next to nothing. It seem that the ATTACK knob has no effect at any setting.

Does this sound like a bad IC?

Thanks.

No, it actually sounds more like something is wrong with the build. The usual advice applies here: post some clear picture of the pedal, front and back and of the off-board connections and we can see if we can help you troubleshoot the problem.

Mike

I have attached pictures for assistance. I have also measured the transistor voltages and they are right on compared to other postings:

Source = 8.97 Vdc

( E B C)
Q1 - 1.97 2.38 6.75
Q2 - 3.67 4.26 5.05
Q3 - 0.00 0.00 8.50
Q4 - 0.00 0.00 8.50
Q5 - 8.10 8.50 8.60
Q6 - 0.31 0.88 5.50
Q7 - 0.31 0.88 5.49

Also measured the IC pin voltages:

1 - 4.45
2 - 0.00
3 - 0.00
4 - 1.00
5 - 0.00
6 - 4.10
7 - 4.10
8 - 4.20
9 - 8.50

Anyone ?

I don't see anything jumping out at me. Make sure to recheck all of your component placements and reflow your solder points.

Thanks. Will do. Just for my information... Do you know about what the compression ratio runs from on this device 1:1 to 1:?

Coolhand:

I think I got it working...

Could you provide any insight into how the SUSTAIN and ATTACK controls work? SUSTAIN seems to be another LEVEL control in essence. Full counter-clockwise there is no signal. Full clockwise increases volume.

ATTACK is something else all together. It's subtlety is imperceptible. I have come across posts that say the ATTACK is really a "release" control. I am not getting any sort of "pumping" at all in for compressor release at either extreme of the ATTACK control. I "think" there is some initial transient change with the ATTACK control full on, lending a bit of pick attack clarity with high ratio settings - but it might be a placebo effect by changing the ATTACK settings.

Your thoughts?

COOLHAND:

What do you get for a DC voltage on C2 (collectors of Q3 and Q4) through the full travel of the ATTACK knob? I only get about 1/10 of a Volt difference from full clockwise to full counter clockwise. Is this normal behavior?

Reason I am asking is the ATTACK knob does not seem to be functioning correctly. It appears that the compressor's release time if fixed at VERY quick regardless of the ATTACK knob setting.

The parts list / schematic shows a 250k Reverse Audio Taper pot in this position. Wouldn't a 100k linear work better in this position and keep more with the original ?

Please advise.

Mandarine

It might be later in the weekend before I will be able to check this one. Give me a couple of days.

Coolhand:

Hoping you are familiar enough with this circuit to help here. There are a couple of things that I am not sure about with this compressor - if is it normal behavior?

First is the sensitivity of the SUSTAIN pot. It is only usable between the 3 o'clock and 6 o'clock (full on) areas. Anything below 3 o'clock doesn't provide enough output level to be useful. Not enough make-up gain in the following circuit. I have read that swapping the SUSTAIN control with the same value but a reverse audio taper makes this control more useful. Thoughts?

Second is the ATTACK control. Nobody home here. As I stated previously, the DC voltage at the Q3 and Q4 collector junction only varies by a tenth of a Volt across the full range of the ATTACK pot's travel with no input signal. I am theorizing that without a guitar AC signal present on the bases of Q3 and Q4, there is no path to ground for the DC Voltage at the collectors, thus the +V is just sitting there with no where to go. As a guitar signal is present on the bases, Q3 and Q4 conduct to ground changing the collector's DC voltage as well as the base of Q5.

As I stated before, I can't get any change in compressor release time with any setting of the ATTACK knob. I was wondering what voltage you were seeing on the Q3 and Q4 junction throughout the ATTACK knob's travel with no input signal present.

I checked all transistors and diodes before installing them, so I am stumped. Checked all solder joints.

Please help!

I wanted to correct my earlier voltage readings on my BA6110. I was apparently not pushing the Volt meter positive probe into PIN2 hard enough. IT is the same as PIN1


1 - 4.45
2 - 4.45
3 - 0.00
4 - 1.00
5 - 0.00
6 - 4.10
7 - 4.10
8 - 4.20
9 - 8.50