Build Your Own Clone Message Board

Hi Folks!

New to BYOC and new soldering, so I greatly appreciate this supportive community.
I finished building a Blue Overdrive recently that lights up and works in bypass, but no sound when engaged. I checked that all components are in the right place, and reflowed all joints (doing connections directly behind the Gain pot from the component side). Pictures attached.

(Also, yes: I'm testing with the IC chip inserted, battery hooked up, and a cable in the input jack...I wish one of those had been the issue!)

I suspected the back of the Gain pot might be shorting against the PCB, so I took the guts out--sure enough, it was making contact with a joint. I hot-glued a bit of credit card plastic between the gain pot and PCB. Same result: bypass works, LED works, no sound when engaged.

Tested footswitch per: viewtopic.php?f=10&t=31545
...and continuity is all good.

Tested IC pins per duhvoodooman's instruction here: http://www.byocelectronics.com/board/vi ... ve#p492904
...and am getting strange readings, as follow:
-pin 1: 1.65V
-pin 2: 1.65V
-pin 3: 1.20V
-pin 4: 0...yay, ground worked out!
-pin 5: 1.38-1.39V
-pin 6: 1.68V
-pin 7: 1.69V
-pin 8: 2.42V

What might my next step be to get this gizmo working?


Cheers!

Yeah, those op amp voltages are very low--you should be seeing ~8V on pin 8 and ~4V on 1, 2, 3, 5, 6 & 7. First thing I would check is if the R2/R3 voltage divider resistor pair at the bottom right of the PCB is functioning (see labeled PCB image below). You should be seeing 8V on one side of R2, 4V on the other, then 4V on one side of R3 and 0 (ground) on the other. The two resistors should both be 10 Kohms.

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

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

The extremley low voltage on pin 8 suggests 3 things:

1. The op amp is damaged. Perhaps it was installed backwards at first.
2. You've got the wrong transistor in the Q1 spot or the wrong value in R1.
3. You're battery is almost dead.

_________________
*patience is a virtue*

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

Duhvoodooman and Keith, thank for the quick responses!

Alright, I triple-checked transistors: everyone's where they should be.
I know that I was very careful to install the IC chip with the right orientation each time, and not bend up the pins.
Checked R1: it's 2k2 indeed.
Checked "9V" battery voltage: 5.8V.
(This was a plastic-wrapped battery I only unwrapped for testing, although I did leave a patch cable in the input jack one night between fiddling. Wish I'd thought to test it right out of the wrapper!)

So, with a proper fresh battery hooked up, the IC pin readings are:
1) 4.16V
2) 4.16V
3) 4.14V
4) 0V
5) 2.82V
6) 4.16V
7) 4.16V
8.32V

What does pin 5 tell me, then?



Test results:
R2) 4.12V and 8.27V
R3) 4.11V and 0V
And both are 10kOhms. w00t.


I plugged in the pedal, and it actually seems to be functioning fine now with a new battery, despite whatever weirdness is indicated by pin 5...?

I wouldn't worry much about that pin 5 voltage--I see that from time to time & not sure why. But the rest of the voltages look perfect and the pedal is running, so unless it goes south on you, ENJOY!!

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

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

Rock'n'roll, thanks for all the help, y'all! Really looking forward to more of these builds.