Stage Center Reverb -- Oscillation and static -- Please help

[Triffid]

Hello.   I was active on these forums quite a while ago but since lost the time to for this hobby.  Well, I'm trying to get back into it.  I left the Stage Center Reverb project I was building over a year ago unfinished and I am now trying to rebuild it.  I used this schematic ... http://www.generalguitargadgets.com/diagrams/stage_center_reverb_sc.gif.

I know this is hard to help without sounds or pics but I worked on this for 3 or 4 hours yesterday with not luck, so I'm just looking for some hints as to what might be wrong... for motivation if nothing else 

I used only perfboard to build this... but I know the curcuit itself is functional because afterwards I connected the curcuit to my test breadboard and it worked just fine.  See this pic to know what i'm talking about by test breadboard... http://castagno.org/reverb.jpg.  Pic taken before pcb'ing the curcuit (obviously)

So it sounded great and I was all excited... then I boxed it up in a home made wooden box I built.  The problem started as soon as I plugged in the curcuit.  I used a toggle dpdt instead of the normal footswitch 3pdt for bypass and as soon as I flipped from bypass to the reverb I hear a squeel that starts high and slowing drops down to a mild tone with some static in it.  I thought that sounded kinda funky so I did it again... switch to bypass, back to curcuit... same thing... sounded like an old nintendo game or something    

So I hit the guitar strings and I can hear them just fine... at least some signal is getting through.  I don't hear any hint of reverb though.  Anyway, here are some key notes that may be of some importance, maybe not

1.  The oscillation (or what ever it is) increases/decreases enormously when I do any of the following things... Move any part of the project around, touch/let go of the output wires (going from dpdt switch), touch/let go of the (+) wire to the curcuit.

2.  I removed everything off the box at one point, it is just a naked curcuit right now.... the problem still persists.

3.  I did build on a charge pump into the pcb layout.... but again... I know this was working before wiring/boxing

4.  My wiring wasn't exactly the same as the wiring diagram @ general guitar gadgets (http://www.generalguitargadgets.com/diagrams/stage_center_reverb_lo3.gif)  I used a dpdt toggle instead 3pdt foot switch,  I used just a dc plug and no battery, I didn't put an led on it, I used 2 mono jacks and no input switch.

I stared at this thing for like 2 hours trying to figure out what was wrong.  I double/triple checked everything I could and couldn't find anything obvious.

Like I said... I'm just looking for ideas maybe... something to keep me from repeatedly stomping on this, before its boxed 

Thanks in advance for your help and patience

[cx_deluxe]

Sorry to hear it's not working out.  Having never built a SCR, I won't be of much help.  I did build this one a couple of weeks ago, and it works alright: http://sound.westhost.com/project34.htm

You said you built a charge pump and there's batteries in the picture.  How did you take care of the dual supply when you switched over to the DC plug?  In my limited experience all of my issues with nintendoish squeeling have had to do with inadequate power supply.

If worst come to worst you can tear it all back down and re-build it.  Clean slate.  If you built it once and it worked you can do it again, dammit!  It sucks, I've done it.  A few months ago I knew the EA tremolo circuit backwards and forwards.  Good luck!

[Triffid]

Sorry to hear it's not working out.  Having never built a SCR, I won't be of much help.  I did build this one a couple of weeks ago, and it works alright: http://sound.westhost.com/project34.htm

You said you built a charge pump and there's batteries in the picture.  How did you take care of the dual supply when you switched over to the DC plug?  In my limited experience all of my issues with nintendoish squeeling have had to do with inadequate power supply.

If worst come to worst you can tear it all back down and re-build it.  Clean slate.  If you built it once and it worked you can do it again, dammit!  It sucks, I've done it.  A few months ago I knew the EA tremolo circuit backwards and forwards.  Good luck!

It Works

Thanks for the advice.  The charge pump takes care of the dual supply... MAX1044 is the trick if i'm not mistaken.  it supplies -9 and +9 from a single 9v source... here is the pic... http://www.generalguitargadgets.com/diagrams/stage_center_reverb_lo3.gif. 

Basically I suspected faulty ground connections, so I removed all grounds and reconnected using pure star grounding to my curcuit board.  This worked like a charm... not even a faint buzz anymore and all the reverb I could want.  Before I kinda hand the grounds chained to each piece.  BAD IDEA.  For now on it's only star grounding for me.

Thanks

[cx_deluxe]

good to hear.

That tank you're using.  What is it?

Mine ISN'T the one the stage center schemo calls for, so I built something else.  I'm not especially happy with my unit and I'd like to try out a SCR.  Guess I could just breaboard one up and see. 

What kind of a reverb sound were you looking for? (think Lush or Surf)
I want really 'squirty' surf reverb.

[Triffid]

good to hear.

That tank you're using.  What is it?

Mine ISN'T the one the stage center schemo calls for, so I built something else.  I'm not especially happy with my unit and I'd like to try out a SCR.  Guess I could just breaboard one up and see. 

What kind of a reverb sound were you looking for? (think Lush or Surf)
I want really 'squirty' surf reverb.

I am using a tank that I pulled out of an ss fender princeton i have... Its accutronics #8EB2C1B.

from accutronics web site...
8 for Type 8
E = 800 Ohm Input Impedance
B = 2575 Ohm Output Impedance
2 = Medium (1.75 to 3.0 sec) decay time
C = Input Insulated / Output Grounded
1 = No Lock
B = Horizontal Open Side Down

I kinda wanted a "big room" type reverb... I play mostly blues and was specifically looking for that reverb interaction on slow bends and what not.  This seems to do the trick for me.

I did make a couple mods to the schematic while it was breadboarded.  Can't recall specifics since I'm at work and the mod schematic is at home, but it involed modifying around the tank receiver opamp to give a little deeper sound and mod'ing around the mixing opamp to get a more constant volume when the effect is true bypassed.

Unfortuatly I don't really have any advice on how to get a surf type reverb out of the State Center/Tank... mines not slappy or 'squirty' at all.

Good Luck