Electro harmonix small stone acting up

[orange418]

Hi.  My last problem has to deal with my elelctro harmonix small stone from 1977, the first version ( I think).  When I put the battery to it ( brand new) the flanging and volume is very low  and when I push the bypass switch the sound is louder, clean, and I get a loud popping.. What could be causing this?  I'm baffled..  Could the caps be going bad or do I have a bad chip or transistor somewhere.. Of course any ideas and solutions would be helpful...Where would I start?  Thanks..

[GibsonGM]

Could be a whole heap o'things, Orange, but you're in the right place )  Hopefully you have built a project or 2? You'll have to be comfortable with some things before you'd want to dig into this.  Don't mess up your vintage pedal!  If you want to proceed, here ya go:

So, you have a fresh battery at about 9V.  Make sure, lol. I've put dead ones in by mistake, ha ha. Be sure it's not a bad cord or something...I know, I know, you did that 

FIRST - if the popping occurs IN bypass, the connections to/from the switch, or the switch itself may be bad - check here by opening it up, moving the wires and throwing the switch.  The problem should come & go as you do.   You don't need the rest of this, if this is the case...just fix/replace the switch and/or wires. Most common issue with your symptoms.

If everything's ok, then I'd suspect something is screwy with the power to the unit, maybe at the board, cap(s) possibly - electrolytics go bad after 10+ years.  But we don't know enough to be sure.  So here's what we do: disassemble the unit to get at the components, and check the IC's/transistors inside and record the voltages, and any part #'s from them.  This wil ensure that the IC's have power, and that your power supply/bias etc. is working. Someone who knows the small stone well will probably see your post and tell you if the voltages are typical.  Is anything warm to the touch when it's on?

Next, probe the circuit with an audio probe.  You can find out how to make one in the link at the top, Debugging page. Plug a CD or something into the unit to have a signal going.  Start with where the tip of your jack connects to the board, and work into the circuit until you can't hear the signal, or it sounds very wrong.  Could be caps, yes! If so the audio signal will die behind one of them.    This should get you started...it's helpful to find the schematic and locate the outputs of op amps, etc., to make tracing the audio signal easier!
Post back with more info, you'll get help here.  Good luck!   

[rockindutchboy]

I'm right there with ya, Orange.

I have the same exact problem...but it seems that it isnt doing it today. It's not the battery for one thing, since mine is powered directly from a 1spot.

Whatever the case, I think I'm gonna replace the switch.

[orange418]

Well Gibson GM, I hope you're reading this because you're a genius and I thank you.    Well I haven't really been successful in my mind concerning this hobby, but I try to find info where I can, and this forum is a God send for us hobbyists.. The small stone has been sitting in hiatus for a about six months and i finally got around to having the patience for taking it apart again, and I removed the sticky white tape covering the bottom of the switch not realizing that there were screws holding it together, otherwise I never would've sprayed electrical cleaner that melts everything in sight...    Live and keep learning I suppose.. Low and behold, the switch fell apart because it was cracked in two pieces..After jumpering it together I got a surprisingly loud kind of washing machine warble, and I was amazed at the volume.. I'm not sure if the pop went away but the switch was corroded so it probably needed cleaning or scraping anyway to rid the metal of years of piled on oxidation.  What got me into this was my neighbors VCR in the trash that had extra wires that I needed, so I decided to see if I could built a fuzz face clone...Then I purchased a very ugly and almost worthless Deluxe electric mistress on ebay that only had the casing, the power transformer, and circuit board with all other conponents except the important chips.. People at the guitar store said it couldnt be restored and made fun of me for it.. After sitting for two years in basement, one weekend I decided to order parts from small bear and rebuilt it from the ground up.. Before that i've made horrible mistakes late at night tired burning up traces and driving myself crazy but it goes to show that if you walk away and have a clear head later the solution will somehow show up... Thanks guys...