Debuggend LM3875 SE amp still bugs !

Started by petemoore, February 19, 2010, 11:05:52 AM

Previous topic - Next topic

petemoore

  Can't figure out where I'm missin' it !
 Voltage on pin 3 output is 15 or so, same with the inputs, using 3x9v for 28 V supply.
 I wrapped my red/black wires across a battery [red to button of 1 battery, black to buttonhold of a battery], third battery in the middle = off switch...2 pieces of duct tape and a battery..
 yupp, triple checked all the grounds, have the 1k/10uf to gnd. off pin 8, the "20k's plus a 50pf triangle between 8 and 3, 3 has the *2.7ohm [actually *1.6ohm/ .1uf to gnd.
 Iow, been back 'n forth on it and figure theres a trick i'm missing, but I see no mute pin, everything else is as shown on the single supply application diagram...except only little clickies when power up/power down, thumbuzz and Telecaster at input makes no output.
 Hmmmmmmmmmmmm static sensative, I tried to not touch the pins and did the whole shebang on a damp cutting board...Hmmmmmm
Convention creates following, following creates convention.

R.G.

If we had much of the information from "what to do when it doesn't work" it would be easier.

Just a thought.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

petemoore

  No good when it was cold solder on pin 4, packed behind and within with hidden probe finding ground strand...it's all in the timing of the beep, very small difference in timing between the stray-ed strand and pin 4.
 
Convention creates following, following creates convention.