SD-1 won't overdrive

[cheeb]

I built a blender and connected it to my stock SD-1 a la Sparkle Drive. It worked like a charm, after some initial issues. Never had a problem with the blender working, never had a problem with the SD-1 working, and the two together was something magical, I thought. Until today, when I was gonna jam around with it to find the settings I liked best, when the overdrive was gone. The blender still worked, and the volume pot on the SD-1 worked, but the tone and drive pots did nothing and a totally clean, same-as-bypassed tone came out. There's no sign of anything being fried, it hasn't been dropped or stomped, it hasn't been modified at all since it worked last. My effect just won't affect. Anyone seen this problem?

--Cory

edited to add: I disconnected the blender and wired the SD-1 back to stock and it's exactly the same.

[Barcode80]

sounds like the opamp might have died...

[cheeb]

1. What do I need to test for?

2. What readings should I be getting?

[cheeb]

Boooomp

[petemoore]

  Name and show link to circuit schematic.
  *SD-1
  If you're using a layout or PCB post a link to that too.
  *SD-1 [Boss]
   Is there a connection between circuit power supply V+ and Gnd. under any of all power supply 'conditions' ie...is there shorting under and 'normal' switching conditions of input jack or DC jack or any other time?
  *YES   /    NO  [enter comments
  Measure battery voltage.
  *X.X2VDC
  Measure battery voltage with circuit loading
  *X.21VDC
If using a power supply, what does it say on it about voltage rating?
  *Xvolt
  Also name power supply type
  *AC  or DC output
  test the voltage of the power supply.
  *9.2VDC
  Test votlage of power supply with circuit connected
  * .22vdc
  Is the circuit npn-negative ground?
  *Transistor type [npn/pnp...jfet, mosfet, Ge, etc.
  *Circuit polarity [neg gnd. or pos. ground?
  *Opamp type [Dual, single, OTA, CMOS...other
  connect DMM to ground, and test for continuity at every point in the schematic with a ground symbol, from the most 'distant' [test points should be beyond all connections and solder joints].
  Test the cables that are plugged if they can be plugged in, at the plug sleeves which connect to guitar and amp
  Is there continuity at all 'distant circuit ground points
  Stage 2
  Connect power supply, if there is a large current draw [ie voltage drops by 10% or more, disconnect power and post that result].
  Is there a >10% voltage drop in battery when circuit is connected?
  *Yes  /  No
  What voltages are measured [using ground as reference voltage =O.0V], using DMM at all active component pins?
  *Dual opamp
*1  4.5v
*2  4.5v
*3  4,5v
*4  0.0v
*5  4.5v
*6  4.5v
*7  4.5v
*8  9v
-----
  *Single opamp
*1  NC
*2  4.5v
*3  4.5v
*4  0.0v
*5  NC
*6  4.5v
*7  9v
*8  NC
-----
*Transistor type
  *NPN
  *PNP
  *Jfet/mosfet/BJT/Ge?
  *Transistor part #
  *Data sheet pinout information
  Pin Voltage
  *D 9v         
  *G 2.2V
  *S  .21V
  Or substitue 'E/B/C if using bipolar transitor
  List any pertinent comments and questions.
  Stage 3
Audio probe, and list results and comments.
  Test that all stages are 'separated' by DC blocking capacitors,
  Can you physically see that a capacitor is properly wired to the input and output of each active component stage? ie signal path must go through the cap to enter or exit the active stage.
  The circuit debugging may have limited results if the answers with * are not known or posted.
  BTW the opamp pins for most distorters [gain stages] are more than optimal, bias is 'centered' at 1/2 the power supply, except for the power supply pins [the 9v and 0.0v ones.

[cheeb]

 

I checked everything listed above, and it all checks out, except the opamp voltages. It shows little to nothing is happening in or around it, so I'll throw another in and see if it fixes the problem.

[cheeb]

I came back to this after a few months of it sitting in a drawer. I put a new IC in it but it still doesn't drive.

The volume knob also affects the bypassed signal, something I hadn't noticed before. Anybody got any new ideas?

[petemoore]

  I checked everything listed above, and it all checks out,
  could you describe details or at least what 'everything' is, also what is 'it'.
  Did you audio probe?
  except the opamp voltages.
  textbook voltages, too 'right' looking, battery at exactly 9v and OA's at exactly 1/2v looks too clinically exact, the voltages posted show perfectly biased OA's.
  It shows little to nothing is happening in or around it, so I'll throw another in and see if it fixes the problem.
  "Shows"..hmmm, what type of nothing barely or doesn't happen around?
  The volume knob also affects the bypassed signal,
    I suppose a #PDT switch is offered for bypass, if the volume control controls in 'bypass', technically the circuit is not bypassed...the switch wiring needs debugged.
   something I hadn't noticed before. Anybody got any new ideas?

[cheeb]

I can post all my voltages if you'd prefer. What I meant by nothing happening in the IC was I'm getting readings of 0.00 at every pin. A new 4558 didn't help.

The volume pot does nothing at all when the pedal is engaged, but limitedly controls volume when the effect is "bypassed".

[frokost]

Build an audioprobe. Search the forum for instructions on how to use it. With the audioprobe and the debugging thread, the need for posting on this forum diminishes greatly. Really - an audioprobe is essential for debugging.

[petemoore]

  I can post all my voltages if you'd prefer.
 that's ok, if they're within' operational bias.
 What I meant by nothing happening in the IC was I'm getting readings of 0.00 at every pin.
 A new 4558 didn't help.
 k, bypass can't be wired right.
 and 0 voltage at all pins probably means PS isn't wired right.
I would get the debugging page and use that as a template to fill in the blanks..scehamtic, bypass wiring diagram...something to represent and show more exactly what you have going on there.
 No power to board could be...DC jack wiring, Input jack wiring...other miswire, inadvertent grounding, possibly something else.
 Whether you have a DC jack or input jack PS defeat wiring assignments I forget, posting all this concisely in 1 post makes it much easier to find the pertinent informations, as it is were at 10 post per thread, it ain't werkin' and I don't know what you've got there.