# ADHD Voltage Values



## Bgrapt (Mar 3, 2020)

I'm currently troubleshooting my ADHD build. I'm recording all of my voltages for the IC and transistors as well as the references in the schematic. 

Unfortunately the build docs doesn't list what these ought to be, and I'm having a hard time tracking them down online.

Does anyone who has built this pedal before have them handy?


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## Chuck D. Bones (Mar 4, 2020)

Post your measurements here and we'll evaluate them.  Also include the settings of all switches and pots when you made the measurements.  Proof-read your post before hitting the Post button, you don't want to give us bad info.


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## Bgrapt (Mar 20, 2020)

Chuck D. Bones said:


> Post your measurements here and we'll evaluate them.  Also include the settings of all switches and pots when you made the measurements.  Proof-read your post before hitting the Post button, you don't want to give us bad info.



Finally got around to working on this some more. 
As I went around the circuit taking measurements I found some very off resistances. I either grabbed the wrong resistor without checking or had a couple bunk ones. A lot of my voltages are suspiciously low, maybe this is the cause? 

On IC pin 8 (V+), I'm only getting 1.26-1.32 V depending on the switch being open or closed. Pins 1,2,5,& 7 read 0.73-0.79V, pin 3 is 0.3-0.32V, and pin 4 (ground) is 0
Q5/6 are both hovering around 0.60-0.66 V on 2 pins, with the 3rd at 0. 
Q4 has pin 1 at 0.06V, pin 2 at 1.17V, and pin 3 at 0.41V.
My pair of 2N7000 are reading 0.62-0.65V and 0.73-0.84V on their sets of mirrored pins.

I have tripled check all of my solder joints and continuity throughout the entire schematic (which was super fun to do because this layout does not have R1, R2, etc. but the values...). The only place where what I had on my board was different than the schematic was in the LED. On the schematic, it is written as V+source-> LED -> RLED-> Sw. On my board I traced it to ICpin8 (V+) -> RLED-> LED ->Sw. (As far as I know this is a insignificant change.)

Also I am getting no audio signal when the circuit is engaged. I do have sound while bypassed. And no power to my LED. 
All pots are maxed out, I have switch 2 bypassed to true bypass, and switch 1 on LP. 

My next steps are to fix and quadruple check my weird resistance values, retake all of my voltage measurements, and hope for the best.

Good thing there's plenty of time for projects these days.


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## Chuck D. Bones (Mar 20, 2020)

Pin 8 should be 9V or thereabouts.  Check R20, it should be 27R.  According to your measurements, it's not even close.  You didn't post a pic, but that's ok because *you *need to inspect every part and make sure they're right. If you're not clear on the resistor color code, there are internet resources for that. The bags they came in should be all be labeled, so check that first.


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## Barry (Mar 21, 2020)

Did you take those resistor readings with them in circuit? One leg needs to be lifted to accurately measure them, better to do as Chuck said and verify the values are correct first.


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## Bgrapt (Mar 24, 2020)

Barry said:


> Did you take those resistor readings with them in circuit? One leg needs to be lifted to accurately measure them, better to do as Chuck said and verify the values are correct first.



Yea they were in the circuit, but I went ahead and swapped out R20 and Rled. I double checked the values off board this time and they're correct.

Voltages are now IC pin 1,2,6,7 4.47V, pin 3 1.85V, pin 5 4.38V, pin 4 0, pin 8 8.98

2N7000: Q2 p1 4.45V, p2 4.42V, p3 4.42V. Q3 p1 4.42V, p2 4.45, p3 4.45V.

2SC1815: Q4 p1 2.90V, p2 5.99V, p3 2.54V.

2N5457: Q5 p1 1.05V, p2 7.83V, p3 0. Q6 p1 7.88V, p2 1.00V, p3 0.

Still no signal, but the LED comes on now. Little victories, right?


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