Univox SuperFuzz debug

Started by captntasty, July 18, 2006, 02:52:18 PM

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captntasty

Hi all,  I hope some of you kind folks might help me debug the SuperFuzz I just completed  (http://www.diystompboxes.com/smfforum/index.php?topic=47142.0).
I won't bother to post any voltages because the problem starts before that.  The board doesn't get power and the batteries are roasting themselves - a battery reading nearly 10 volts was reduced to 7.5 in a matter of minutes.  The pedal bypasses but no sound from the board.  The LED does not light either.  Reversed from negative to positive ground the on the off chance I read something wrong - no change.  I've built many pedals (more than I really know wht to do with ;)) but used the last layout on the topic listed above (from Dan N)which I'm not as familiar with.  Polarity on caps is good, no jumpered traces.  I did wire it for true bypass with a 3PDT identically to how I have on other pedals successfully - could that be a problem?  I just recieved a parts shipment and may have gotten the wrong stereo jack - open tip, open ring - should it be different?

OK, I've rambled quite enough.  Any help is much appreciated.  Thx 
It is no measure of health to be well adjusted to a profoundly sick society. - Jiddu Krishnamurti

Sir H C

Somewhere you have a short.  I would pull the battery, and measure the resistance between the two contacts on the batttery connector.  From there look for either a miswiring or short somewhere in the line.  Do you have an AC adaptor or how are you doing the battery with the 1/4" jacks.  These are places where shorts can come into play.

Mark Hammer

Good chance you have the battery connected somewhere where it shouldn't be.

captntasty

#3
Wired as per JD's site http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_ig_dcjack.gif

There is continuity but no resistance with plug inserted at input - No continuity with jack unplugged.  This is pretty much how it should be, right?  Frusteratin'...  When I test voltage from the DC +9v jack it is reading 9v on every lug including the center ground lug (with Neg lead on DMM to -9v on input jack, Pos DMM to either power lug on DC jack).  When I do the same test on the sleeve/ground lug on the input jack I get zip.  When I test from -9v on the input jack to any ground point on the board, switch or jack it reads 9v.  If you can understand my gibberish - this is all bad, right?  And I know I should be able to suss it out, but I don't get it -  ???   Does it mean that the + board input or power rail is connected to the board ground rail making the battery loop back on itself?
It is no measure of health to be well adjusted to a profoundly sick society. - Jiddu Krishnamurti

Dan N

#4
Steve did a nice layout on that sucker. The only thing I see wrong is that there is no current limiting resistor for the LED. At least, I don't see one. I don't know how that would affect battery drain.

I'd be looking hard for some kind of trace touching problem. Test every trace for continuity with the power supply traces.

Hope you get it working!

Edit- Oops! RLED is that resistor. I was thinking it meant red led! Oh brother...


captntasty

Yeah, the RLED thing had me for a minute - I'm used to it being offboard.  Good news - I found the problem...  The bias 1 pad/R22k pad was jumpered to the R100k pad.  I also noticed, in the schematics I have, input cap comes before R22k so I switched them.  Would it make a difference to have them R first cap second?  Any advantages in sound quality?  Any how, thanks for all the help.  So much appreciated...
It is no measure of health to be well adjusted to a profoundly sick society. - Jiddu Krishnamurti