Some Basic Debugging Voltages

[Scruffie]

I figured this might save some time, some basic voltages to expect for debugging, all readings are approximate, use your judgement. They may not apply to everything, but in a pinch they might just help solve your issue.

This all applies to positive voltage effects!

If you have a circuit with standard ground, V.Ref and 9/12/15/18V supply, any audio path dual opamps you can usually expect to see;
1 - 1/2 Supply
2 - 1/2 Supply
3 - 1/2 Supply (Sometimes this may show lower)
4 - 0V
5 - 1/2 Supply (Sometimes this may show lower)
6 - 1/2 Supply
7 - 1/2 Supply
8 - Voltage Supply

If the pedal uses a charge pump to achieve +/-9V or Split Supply, the audio path opamps should read;
1 - 0V
2 - 0V
3 - 0V
4 - -9V
5 - 0V
6 - 0V
7 - 0V
8 - +9V

In effects with modulation, if you have a dual opamp LFO at 9/12/15/18V (this will have a rate control connected to it) you should expect to see;
1 - Varying Voltage
2 - N/A
3 - N/A
4 - 0V
5 - N/A
6 - N/A
7 - Varying Voltage
8 - Supply voltage
The varying voltages here indicate that your LFO is running, the N/A pins will vary, the main thing is there is moving voltage.

8 Pin BBDs (3007 etc.)
1 - Supply Voltage
2 - 1/2 Supply
3 - This will be changed by the bias pot, start at 1/2 Supply and adjust until the effect passes.
4 - Between 0 - 1V
5 - 0 V
6 - 1/2 Supply
7 - Just above (approx 1V) pin 3s voltage
8 - Just above (approx 1V) pin 3s voltage

8 Pin BBDs (3207, 3208 etc) you should see
1 - 0V
2 - 1/2 Supply
3 - This will be changed by the bias pot, start at 1/2 Supply and adjust until the effect passes.
4 - Supply or up to 1V below
5 - Supply Voltage
6 - 1/2 Supply
7 - Approx half supply (varies with pin 3)
8 - Approx half supply (varies with pin 3)

14-Pin Package BBDs (3005, 3008)
1 - Supply Voltage
2 - 1/2 Supply
3 - Just above (approx 1V) pin 7s voltage
4 - Just above (approx 1V) pin 7s voltage
5 - 0V
6 - 1/2 Supply
7 - This will be changed by the bias pot, start at 1/2 Supply and adjust until the effect passes.
8 - Between 0 - 1V

14-Pin Package BBDs (3205, 3208)
1 - 0V
2 - 1/2 Supply
3 - Approx half supply (varies with pin 7)
4 - Approx half supply (varies with pin 7)
5 - Supply
6 - 1/2 Supply
7 - This will be changed by the bias pot, start at 1/2 Supply and adjust until the effect passes.
8 - Supply or up to 1V below

[mgwhit]

Thanks for posting this, Scruffie!  This should be a sticky.

[Stomptown]

Thanks for posting this, Scruffie!  This should be a sticky.

This!  Thanks Scruff!!!

[dont-tase-me-bro]

Thank you. Just emailed this to myself

[lincolnic]

Thanks for posting this, Scruffie!  This should be a sticky.

I was already planning to write this exact post before I finished reading. This is awesome!

[FloorIt]

You rock!

[Scruffie]

Haha thanks guys, really this is actually a selfish experiment though to save my self time

Time will tell if it'll be of any use or just add confusion, please post here if it does prove useful so I can know if it's worth adding to.

My only worry is that some people will try these and make incorrect assumptions about their builds... but if you're not sure always post in the tech forum!

[selfdestroyer]

How the hell did I miss this post. Great job Scruffie this will help out a lot.

Cody