SRV Special problem

[Sody54]

Mornin,

I've got sort of an odd problem I've run into with one of my builds.  I built an SRV Special tube screamer ciruit using Ulysses vero layout (Great layout BTW Ulysses!!).  Took me a while to debug (my goofs), but I finally got it working about 1am Monday morning.  I then messed with it for about 2 hours, doing some recording of the different tones and settings with my amp.   I then emailed our lead player and asked him to stop by after work and pick it up to try it out and see how he liked it.  About 3:30pm I went down to play around with it a bit more and found that once activated, there was no signal.  The bypass works fine, so it's not the jacks or my cords.  I also tested the battery and had a strong 10.45V.  I then checked for a ground from the board to the case, and replaced the 2 tranny's and 4558, thinking that if there had been a short, it may have damaged something.  No luck. 

The pedal hadn't been touched since I left it.  Was in the same place I left it with the cords disconnected.

Has anyone else ever run into a problem like this?   

I'm going down now to put together an audio probe and see if I can locate the problem, but thought I'd drop a line here first and see if I get any hits.

Thanks for any pointers,

Brian
www.myspace.com/crookedcreekband

[GibsonGM]

That's a strange one, Brian.  You definitely should try the audio probe for this problem!!   I might have tried it before replacing the transistors, since more soldering could have added additional problems like solder bridges! 
I would suspect either a secret short to the case that happened when you unplugged the cords, something like that.   Sometimes jacks can be loose, rotate a little, and make 2 things touch that shouldn't!!!    I think you'll find the problem pretty quickly with the audio probe...good luck!  )

[Sody54]

I wasn't resoldering any of the components, because everything I replaced it socketed.  I don't solder any trannys' or diodes until after I've debugged, in case I want to swap anything out.

I'll post after I finish with the audio probe.

Hope it's something simple because this pedal sounds incredible in front of my Fat Tele!

Thanks,
Brian

[ulysses]

this is a really nice sounding circuit.. mine is still working fine..

audio probe would be your best bet.. did you put the opamp in the right way around the second time?

cheers
ulysses

[Sody54]

Sure did.....facing south.  Audio probe is a pain in the butt when everything is all squished together....sheesh.....it's fightin me!  Not being very adept at following the signal path isn't helping matters much either    Oh well....chalking it up to a learning experience

Still no luck BTW....

[Sody54]

Well...now that I've had a little free time to mess with this, I found that I need a drool cup. 

When I swapped out the pop switch I wired up the in to the out and vice-versa.  I know...I know....triple check the wiring and then check it again.  Still not sure what the original problem was.  After re-wiring the 3pdt it started working again.  I may never know.

Thanks for the help guys.  I'm going to go hang my head for a while now....then go and make some noise!

Thanks
Brian

[MartyMart]

No shame Brian, I've made that exact same mistake and a I SHOULD know better !!!!

FWIW - the best one is testing  a new build and thinking "why no sound at all" ? only to look down
and see an empty 8 pin DIL socket !! 

MM.

[96ecss]

No shame Brian, I've made that exact same mistake and a I SHOULD know better !!!!

FWIW - the best one is testing  a new build and thinking "why no sound at all" ? only to look down
and see an empty 8 pin DIL socket !! 

MM.

One time I tested a new build and found it had no sound and the LED didn't work. I turned it over and found that I forgot to put the battery in. 

Dave

[petemoore]

  A million silly things...
  backwards jacks...
  No battery...
  The relevant pins to check on the opamp are:
  the inputs, negative and positive, if in a gain or buffer stage, signal should be present at these pins as well as the output, all three should be 'between the rails' at least, somewhere near 1/2v [or 4.5v of 9v supply] is fine. A gain stage should have more volume at the output than the inputs, buffer would be about the same output as at the input.
A dual oa of course has 4 inputs...a - and a + for each side, and two outputs, all should be biased near 'center' or around 1/2v.
  That leaves V+ and Gnd. pins [unless you're using a compensated OA].
  V+ [pin 8 of dual oa [pin 7 of single OA], should be at the supply voltage [direct connected to 9v?] or very near it [small resistor inserted to help filter, say 100ohm].
  Gnd. should be 0.0v, all grounds connected.
  The probe of the audio probe can be put right on the OA pin, or an adjacent component lead which is connected to the OA pin under test.