Collosalus issue

[Axe_34]

Hi all. Well the streak of trouble-free builds -- including a Dirtbag -- has ended. 

Hooked the Collosalus up to my 9v test rig and I get no guitar signal. I can hear the effect working -- you can hear the flange swooshing and the controls effect the swoosh as they should. The problem is, there's no guitar signal being processed. I checked the usual suspects but didn't see any traces. Component values are good as are the electrolytic orientations.

I am getting some strange voltages on a few chips.

IC1 -- spot on

IC2
1- 7.20
2 - 7.2
3 - 7.18
4 - 0
5 - 0 (!)
6 - 13.71
7 - 15.71
8 - 14.38

IC3 -- spot on

IC4
1 - 4.02
2 - 4.02
3 - 3.98
4 - 0
5 - 7.2
6 - 7.26
7 - 7.26
8 - 14.4

IC5 - spot on

IC6 - spot on EXCEPT pin 5 is showing 7.18 instead of 0

IC7
1 - 1.74
2 - 4.25
3 - 0
4 - 8 mv
5 -  213 mv
6 - 2.5
7 - 1.43
8 - 9.09

IC8
1 - 15.87
2 - 0
3 - 14.46

IC9
1 - 14.46
2 - 7.16
3 - 7.91
4 - 1.37
5 - 0
6 - 7.19
7 - 7.81
8 - 7.81





I sure hope it's not IC9. I dropped $10.95 on that SOB.  

I'm going to spend the rest of the evening audio probing. Wheeeeeeeeeee! What fun.  

Any suggestions are greatly appreciated.

[alanp]

Them's some fancy capacitor solderin'. (Sodder-ing, if I was to extend the bad American accent )

Capacitors react differently to resistors when they're in series/parallel, is your maths right on those?

[Axe_34]

  Frankencaps. 

Just remeasured everything. Caps are fine but I found R26, R27, R41 and R47 are all off way more than 5%. Markings are correct but the values are out of whack. I'll replace those and see where it gets me.

[jkokura]

Be aware that sometimes resistors measure funny in a circuit. Just because they measure wrong in the circuit doesn't mean they are wrong. They interact with other components.

Jacob

[Axe_34]

Be aware that sometimes resistors measure funny in a circuit. Just because they measure wrong in the circuit doesn't mean they are wrong. They interact with other components.

Jacob

Thanks.

Turns out it wasn't the resistors. Problem remains. On to the audio probe!

[Axe_34]

Well, I'm not getting signal on most of the circuit. I have it on the input and first resistor, but nothing after that. Think I'll take another run at this in the morning. 

[gordo]

I have good news and bad news. Good news is that my 117 build works. Bad news is that I finally gave up on trouble shooting and ordered another board. Lazy, I know, but I finally threw in the towel. Your's looks very clean and I think I snuffed mine by lifting traces while trouble shooting. Hang in there, it's worth it.

[Axe_34]

Anyone know if the 3007 is prone to failure (like PT2399s)? Also, is there anyway to check the chip out of the circuit?

[jkokura]

Well, I'm not getting signal on most of the circuit. I have it on the input and first resistor, but nothing after that. Think I'll take another run at this in the morning. 

Based on that info, you need to start by verifying you can get signal into and then out of IC1B - if you can't get signal there, then the chips don't even matter yet.

Since IC1 voltages are good, there must be a reason that you get no signal after R1, and I'd start looking for that.

Jacib

[Axe_34]

Update: I worked my way through the circuit using the schematic and the only places where I'm getting a guitar signal are:

C6, R13 and VERY faintly on Pin 1 of IC1

[Axe_34]

Them's some fancy capacitor solderin'. (Sodder-ing, if I was to extend the bad American accent )

Capacitors react differently to resistors when they're in series/parallel, is your maths right on those?

Culprit found! Replaced the frankencaps with single caps (as close as I could get to the stock values) and we have flange! And chorus! And a vibey thing too. This thing's a very versatile beast.

Thanks for the suggestion alanp!