DIYstompboxes.com

DIY Stompboxes => Building your own stompbox => Topic started by: Evad Nomenclature on February 12, 2009, 11:42:59 PM

Title: TS debug (tons of luck for me this week!)
Post by: Evad Nomenclature on February 12, 2009, 11:42:59 PM
On a bad streak of builds apparently.
last 2 have been buggy on fire up... this one has me stumped.

Built my first TS 808 off the tonepad layout.
Here's whats happening.  I get signal through the effect on the breadboard... The tone pot and volume pot both work, but I don't get any drive.
I measured the voltages on the IC and both of the transistors and it is almost dead on the money what they are supposed to be... all measurements within .02 V of readouts given on the GGG website.
It is obviously an issue with something on the drive pot... or on the board where the drive pot is.
I have checked the orientation of the diodes 5 times (they are correct... Im sure of it)
I added a jumped in the spot where the assym. 3rd diode should be. 
I'm stumped... here's the link!

http://www.tonepad.com/getFileInfo.asp?id=81

Any ideas what would make it do this... I'm sure there is something in this post that is a big red flag to someone =P
thanks much
Evad "The everstumped at debugging" Nomenclature.!
Title: Re: TS debug (tons of luck for me this week!)
Post by: oskar on February 13, 2009, 03:23:40 AM
The first OP-amp is acting as a buffer not amplifying the signal. Either there is a short between the output and the inverting input like one of the diodes is bad or a solder bridge... or there is an open connection in the net going from the inverting input to ground ( or V ref don't remember).


Oskar
Title: Re: TS debug (tons of luck for me this week!)
Post by: earthtonesaudio on February 13, 2009, 07:22:35 AM
What he said.
Title: Re: TS debug (tons of luck for me this week!)
Post by: Evad Nomenclature on February 13, 2009, 09:08:27 AM
Coool, I'll check that out when I get home from school later.