ADHD only passing signal in off/true bypass

[sean2damax]

Anything obvious that I missed here? I’m only getting signal through when the foot switch is in the off position and the bypass switch is in true bypass, so basically I’m only passing signal through the foot switch. I’m fairly new to this but I feel like the IC voltages probably aren’t where they should be.

voltages:
9v @ DC jack pins and -/+ pads on the board

IC:
1: .86v
2: .80v
3: .58v
4: 0v
5: 1.3v
6: .83v
7: .83v
8: .88v

 

[Mcknib]

Your 27R resistor looks wrong can't quite see the colour bands but it looks like at least a 2K7 if it's red purple black brown brown it's 2K7 red purple black red brown 27K

Hard to see if the 4th bands gold or brown or red

That'd mess up your VREF voltages a tad and account for your low IC voltages

 

[PJS]

Are you sure you have written down those voltages correctly? Pin 8 is the power supply pin and should be close to the 9V power supply voltage 8.8V would be about correct. 0.88v is very low and suggests that your power has a problem - maybe a faulty power supply or a short somewhere.

 

[PapaBear]

Your 27R resistor looks wrong can't quite see the colour bands but it looks like at least a 2K7 if it's red purple black brown brown it's 2K7 red purple black red brown 27K

Hard to see if the 4th bands gold or brown or red

That'd mess up your VREF voltages a tad and account for your low IC voltages

4th band looks red to me, 27k

 

[Mcknib]

4th band looks red to me, 27k

#5
I zoomed in and still couldn't see it but everything points towards R20 being the problem

With 1.3v on pin 5 actually pin 8 I think, telling us VCC ain't right and as a knock on effect VREF is way off but every cloud has a silver lining the voltage divider is doing it's thang even though it's not getting fed right, you've gotta love a good old voltage divider
Reply

 

[sean2damax]

Damn you guys can spot a bad resistor well. Much appreciated. Placing a parts order for a few other builds right now so i'll add a few 27r's to the cart and update this post once I pop it in.

 

[sean2damax]

#5
I zoomed in and still couldn't see it but everything points towards R20 being the problem

With 1.3v on pin 5 actually pin 8 I think, telling us VCC ain't right and as a knock on effect VREF is way off but every cloud has a silver lining the voltage divider is doing it's thang even though it's not getting fed right, you've gotta love a good old voltage divider
Reply

You guys were correct. Got the 27k out of R20 and popped in a 27r. Works like new!

Much appreciated.