ICL7660S Falling output voltage?

[patrick398]

Thanks for the fantastic reply. Helped me understand what's going on a little more which is the aim of the game at the end of the day. I'll go back over the circuit tomorrow if i have the chance. I guess there's no way of running the mutron circuit and testing it without the charge pump?

[amptramp]

^

You could always run from external batteries that are at the voltage you would expect from the charge pump.

[patrick398]

Of course! Thanks I'll get on this asap

[patrick398]

Charge pump is now putting out the correct voltages to the board so that's problem number one sorted. Went over every trace with a scalpel so must have been a short somewhere. No signal passing through though so i started audio probing and realised the first 3.3k resistor after the input was in fact a 3M3. I couldn't believe i'd be that stupid so checked the pack and they're bloody labelled wrong. It was a set of about 2000 different value resistors i bought so now i'm going to have to check every value before i use them, what a pain.

Anyway that's beside the point. I want to carry on audio probing but i'm not exactly sure where the signal is going and what it should be doing where. If somebody could give me a rough guide as to where to trace the signal and if possible a brief description of what each section is doing i would be eternally grateful! Very nearly gave up on this but i've been spurred on by my success with the charge pump

[Kipper4]

Geez Patrick I hope you read schematic.

http://www.generalguitargadgets.com/pdf/ggg_neutron_sc.pdf

In the above schematic you can ignore IC3 a and IC3b that's is your envelope detector and led driver.

I suspect that the top ic in your dreaded vero pins 5 6 7 is the envelope detector
And I think the bottom ic is the led driver pins 1 2 3.
Form a quick look.

The signal path is from the gain pot to ic1b ic1a ic2b ic2a
Happy hunting.

[patrick398]

Haha yeah sorry i was being lazy and impatient, really should just study the schematic. The irony is that it's currently the desktop background on my laptop. No excuses!
Thanks for the reply!

[Kipper4]

Yerrrp crack on boyo.