Collosalus Build no sound?

[Spenzerleehorton]

Hi,

i have built the Collosaslus and im getting no sound when engaged?
the problem seems to be with IC4, pin 1 is only 2.96v and all other voltages are off?
IC6 seems to be all over the shop as well!!!!

[jimilee]

Post pictures voltages and honestly, if I were you, I'd build an audio probe, that helps me more than anything.


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[Spenzerleehorton]

hi,

yes i have a scope, so far the problems are coming from IC6 and IC9.
IC9 gets quite hot which is worrying!!
i will post pictures in a bit once I've taken it all out of the case to work on, as its such a pain to try and work on it within the case!

IC6
1 - 9.70
2 - 9.70
3 - 5.38*
4 - 0
5 - 9.64*
6 - 0
7 - 0
8 - 16.14
9 - 16.14
10 - 6.67*
11 - 16.14
12 - 5.34*
13 - 16.14
14 - 16.14

IC9 voltages without 3007 put in

1 - 16.14
2 - 7.15
3 - 10.57*
4 - 9.80*
5 - 0
6 - 6.54
7 - 15.33*
8 - 15.34*

* = too high or low voltage

looks like the MN3007 has blown right?

[Spenzerleehorton]

All voltages look a bit high, could anyone help please as it looks to me like IC5, 6 and 9 have blown?
is there a list of voltages without IC in? or is the list in the PDF without ICs?

[Spenzerleehorton]

Could anyone verify if the voltages in the PDF are voltages with the ICs in or out please?

[midwayfair]

Could anyone verify if the voltages in the PDF are voltages with the ICs in or out please?

You should always assume that voltages taken from a working build are with all components in the circuit unless otherwise specified. For one thing, not every pin of a device receives voltage or experiences current draw when a device isn't in-circuit, so the measurements aren't useful except in situations where you can't figure out whether there's a short to another voltage point.

[Spenzerleehorton]

just checking really, and didnt want to assume.
still wondering why my voltages are off and dont want to blow anymore IC's up, do you have any idea on how to move forward please?

[Spenzerleehorton]

too me it looks like the bias for the 3007 chip is way off as pins 3/4 and 7/8 are way too high?
ive ordered another IC9(3007) but also concered about pins 3,10, 12 on IC6 as they are not high enough, this seems to point to R40, C22, R38, R39 area?

[Spenzerleehorton]

right well I've scrapped that power supply and I'm just going to power with 9v battery until voltages look better

[Spenzerleehorton]

i need to try and find out whether my 3007 still works along with the 4049 if anyone could help please?

[Spenzerleehorton]

To me there is no point putting in more ICs until I know I've got the right voltages, otherwise I will just damage the next ICs.

[midwayfair]

Well, if you are 100% sure that every value you've populated the board with is correct but you think something is connected to the wrong thing on the PCB in a way that's going to damage the ICs, then get out your multimeter and start checking continuity among the parts in that section against the schematic. For example, if for some reason pin 5 of IC6 isn't connected to ground, then you need to either figure out why it isn't or just connect it to ground (because sometimes crap happens and you have to do things manually). [EDIT: Pin 5 should not be at ground. I had to zoom in on the schematic to see that it wasn't jumpered to the other legs of the chip.]

If you are just trying to get to the voltages in the build doc for the IC pins before sticking the ICs in there, then you are going to be waiting until Ohm's Law is no longer valid. The ICs complete a circuit from the voltages sources to ground and therefore draw current. Current draw across resistance reduces source voltage. Again, you will not read the correct voltages listed in the build doc until the ICs are in the circuit. And while someone might come along and happen to have measurements for empty IC sockets in this pedal, you can't count on that having been done or on someone else going back to their build and pulling all the ICs from it to give you the measurements. You could I suppose work out what your multimeter would read at each pin connection on paper based on the schematic. An MN3007's pins 7 and 8, for instance, are connected to +15V through a 47K resistor with no current draw. I should get 15V there without an IC drawing current across that 47K.

You could also get out a breadboard and breadboard the appropriate parts of the schematic for each IC so that you can have a comparison for voltages with and without the ICs. This doesn't mean breadboarding the entire circuit, just enough of the IC connections to give you readings.

[Spenzerleehorton]

I don't think pin 5 on ic6 is meant to be at ground, I have read it's a miss print on the docs.
I will try moving forward with this but it would be much more useful if someone could supply working voltages without the IC in so it's easier to trouble shoot.
Hopefully once I get this working I will supply those voltages.

[Spenzerleehorton]

Does anyone have any voltages for the transistors please?

[Spenzerleehorton]

Seems like I'm on my own with trying to sort this one out then.