Help! My Engineer Thumb Compressor does'nt work

[Agung Kurniawan]

Hi guys...
I have build the Engineer Thumb comp yesterday but it doesnt work. My comp is 4 knob version without the release knob.

Here's the layout I'm using


And here the problem I deal with:
1. There is no compression out of it, when I turn the ratio knob, it become a booster pedal.

2. I get 6,4V on Vb instead of 4,5V.

3. I have add the LED compression indicator. But the LED was doesnt work.

I have double-check anything and there is nothing wrong, Last time I get this comp working nicely on breadboard

And this is my build:


Hope you guys can help me, thanks...

[antonis]

Which is the 4 knob version without the release knob..??

I only know 2-4-5 knobs versions in which 4 & 5 release knob is included...

Maybe Merlin could enlighten us..

edit: OK.. I've seen the 1M release resistor in the junction of inverting input and D2 (wrongly marked as D1 on perfboard) but I can't get the reason to have selectable Attack but not Release..

[Agung Kurniawan]

OK.. I've seen the 1M release resistor in the junction of inverting input and D2 (wrongly marked as D1 on perfboard) but I can't get the reason to have selectable Attack but not Release..

ah, my apoligize. I did'nt mark the diode number.
and also there is a 100k pot for the attack. I have no 1M or 500k pot left on my hand so I use the 1M fixed resistor.

[antonis]

I have double-check anything and there is nothing wrong,

If it's so, somebody put a spell on you.. 

<I get 6,4V on Vb instead of 4,5V.>
Provided recticude of 1M resistors and 9V supply, you've created a voltage follower with gain..
(spell proved effective..)

<I have add the LED compression indicator. But the LED was doesnt work.>
LED doesn't mind if it's working current is 12mA or 20mA (actually, it feels happier on second case..) so you can't put the blame on elevated Vref - but you may freely blame BC237 for being non cooperative. In turn, BJT's base can accuse U2a's Out which, in turn, surely is ready to turn it's nose pointing to it's own inputs..
(tale may turn to saga if you are receptive..)