EDIT: maybe solved? Klon Centaur: going in the trash bin?

[Kost1978]

Hi everybody,
this is build number 18 for me (and number 12 with Mark's layouts), I built this one for a friend who bought the Bitsbox kit. Even if I told him not to buy it and try a different overdrive first, he insisted and I had to buid this "nightmare" in a box (at least for me).
Of course the pedal was not working the first time, not even in "bypass" mode, only the LED was working...

First problem: one of the cuts was still uncut, a microscopical thread was still attached... Once I found it and fixed it the pedal was at least working in bypass mode.

Second problem: no sound when the pedal is engaged, actually if I "move" with my fingers both the TL072 (of course socketed) I occasionally hear a normal sound going to the amp (and the pots seem to work as expected), but most of the time is no sound or low volume sound or a quite "harsh" low sound...

So, my question is: could it be a faulty TL072? Is it possible I overheated one (or both) of them because of the uncut stripe (the upper IC got quite warm before I solved the cut issue)?

I read in the blog's post some of you guys had to try different ICs before find something that worked, so I'm hoping to be in the same situation and want to buy a bunch of them (or the much more expensive substitute OP2134A...).
Or do I still need to search for something wrong in my build?
I went over the board with much more attention after the first problem, I re-did all the cuts and passed a cutter between all the stripes, so I'm confident all the possible bridges are gone...

Thanks for listening...

[IvIark]

Measure the voltages between all the IC pins and ground.  That will give a good idea where the problem is happening.

[Kost1978]

Thanks Mark,
I will for sure tonight.

Didn't do it yesterday cause I had enough of the board, I wanted to throw it outside the window...

I'll post the results as soon as I get them and I'll go over the board again, cause letting some time to pass after the first troubleshooting is probably better...

[Kost1978]

Hi to everybody,
the pedal is now working, I found an electrolitic mounted in the wrong way, as usual it's always the builder first that need to be check...

I got the voltages of the ICs anyway, on the 7660 I got a strange (at least for me) "changing" reading for PINs 2 and 6, is it normal? Do you guys think my other readings are OK?

As far as I know the pedal works as expected: pots working OK, no weird noise and so on...

Thanks!

IC1 TL072
PIN1=4,49 PIN8=9,00
PIN2=4,49 PIN7=4,49
PIN3=1,21 PIN6=4,49
PIN4=0     PIN5=4,44

IC2 TL072
PIN1=4,51 PIN8=7,74
PIN2=4,50 PIN7=4,51
PIN3=4,43 PIN6=4,49
PIN4=0,58 PIN5=4,44

IC3 ICL7660S
PIN1=9,00  PIN8=9,00
PIN2=0->8 PIN7=3,79
PIN3=0      PIN6=4,44->3,86
PIN4=0,57  PIN5=0,58

[Kost1978]

Anyone could check my readings please?

Thanks!

[IvIark]

Something is still amiss, you should be getting around -8.5V on IC2 pin 4, and around 16V on pin 8.  That to me makes me believe something is wrong with the charge pump which the voltages of IC3 suggests could well be the case.  Swap IC3 if you have a spare, check all the components around that IC for orientation errors, misplaced leads, cuts and unwanted bridges.

These are voltages from a working build:

  IC1
1 +4.43V
2 +4.44V
3 +3.45V
4 0V
5 +4.43V
6 +4.43V
7 +4.41V
8 +8.87V

        IC2
1 +4.6V
2 +4.43V
3 +4.43V
4 -8.44V
5 +4.42V
6 +4.43V
7 +4.26V
8 +15.92V

        IC3
1 +8.84V
2 +4.52V
3 0V
4 -4.13V
5 -8.42V
6 +3.97V
7 +5.29V
8 +8.82V

[Kost1978]

IvIark wrote

These are voltages from a working build...

Thanks Mark,
I was also suspecting something wrong from the charge pump...

I'll check again everything and maybe buy a spare for IC3.

Thanks.