Build Your Own Clone Message Board

Hi All,
Apologies if this has already been answered somewhere. We searched and found nothing. This is the first kit my son and I built. It's a Blue Overdrive and it has a few problems.
1. It generates a loud lower octave when I'm playing on the G string from the 12th fret up to the 20th. Also present a bit on the D string and B string.
2. The overdrive seems to die too soon.
3. In general the sound is very muddy

I will have some pictures in a few hours.

Thanks in advance! Hoping to get my son really into it!
Bob

These are the pictures of the circuit board:

https://www.flickr.com/gp/189140226@N05/a0ppiE

I don't see any resistor errors, so that's good. Are you sure that you correctly placed the 3904, 3906 and 5457 transistors, since it's easy to mix them up?

Do you have access to a multimeter and know how to use one to measure DC voltage levels? If so, I'd like to see the voltages on all 8 of the IC pins.

The most common problem that we see here, BY FAR, are poor solder joints. Yours don't look bad, but such problems are often not visually evident. We often recommend working through this process in cases like this: viewtopic.php?f=9&t=52188

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks!! I will check all those things right now! I have a Digital multi meter, been a long time since I used it but I will figure it out.

To measure the DC voltage level on the op amp pins, set your multimeter to the DC voltage mode, indicated by a solid line above a dotted one. Use the 20VDC range setting if it's not an auto-ranging meter. Your power source needs to be connected and there needs to be a cable in the input jack. If the pedal is assembled into the metal enclosure, put the black probe into one of the corner screw bosses of the enclosure--this is your ground connection. If the "guts" are out of the enclosure, use the sleeve tab of the input jack for the ground connection. Then touch the red probe to each point that you want to measure. Pin 4 of a dual op amp like the TL072 should read 0 volts (ground), pin 8 should be your power source voltage, and the other pins should all be very close to 1/2 of the source voltage (nominally 4.5V). See image below for the numbering of the pins.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I finally got the chance to pull it apart and check the pin voltage on the TL072

The battery was testing at 8.95V

Pin 1 - 3.92V
Pin 2 - 3.92V
Pin 3 - 3.92V
Pin 4 - half a mV (0.5mV)
Pin 5 - 3.68V
Pin 6 - 3.44V
Pin 7 - 7.25V
Pin 8 - 7.81

And yes, all the 3904, 3906 and 5457 transistors are in the right place correctly oriented.

2 things I notice here. The first is that the pin 7 voltage suggests that there is something wrong. Not sure what that would be at this point, but it does suggest something isn't functioning correctly. The second is how much your voltage sags when it's under load (the differnece in voltage produced by the battery when you just test it by itself vs. when it's actually powering the circuit). This suggests that the battery is about to die. This has nothing to do with the problem at pin 7 so don't expect that to go away when you replace the battery.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Ok thanks. I will pick up a brand new battery and test the pins again.

Bob