One of the all time iconic Phaser pedals is the Small Stone by Electro-Harmonix. This example is the Russian made version, sent to us by Bondi Intermusic for repair. The stated fault was no signal when pedal activated. Actually, the pedal kind of half worked but with lots of loud clicks & pops, and very little phasing effect going on. Bondi also sent us a Dunlop reissued Fuzz Face from the same customer.
The footswitch was a bit suss, and the Color toggle switch was obviously damaged, so the first thing to do was replace both switches. We installed a Carling DPDT footswitch, and a miniature DPDT toggle switch from RS Components. In spite of this, the Small Stone only worked on one setting of the Color switch and there were still scary pops & clicks from boths switches.
We copied the the wiring from the existing pair of switches to the new switches exactly, so what was going wrong ? We suspected that the problem lay primarily with the Color switch wiring, so in order to correct this we had to do it the hard way, which is to say by reverse-engineering the connections from the switch into the circuitry on the p.c.b., and draw a schematic to compare with those found on the internet.
Sure enough, the connections to both poles of the Color switch were incorrect. Huh ? How did this pedal ever work in the first place ? Well, it’s all a bit of a mystery, but we rewired the switch correctly and the the Small Stone burst into life. However, we still had the loud pops & clicks to deal with, and these were now obviously coming from the board, and not from the switches.
We carefully removed the board once again, and examined the copper side under magnification for any signs of “dry” solder joints and/or hairline cracks in the copper traces. We ended up replacing a dodgy wire link, and this cured the problem of pops & clicks finally. Time to reassemble for the final play test & return the pedal, now 100% functional, to the customer.
How does it sound ? This is one of those classic 70′s phasing effects pedals, with the Color switch giving two different options, either with or without feedback. E-H accomplished this in a different way to their competitors, utilising OTA IC’s (Operational Transconductance Amplifiers), in this case the CA3094E IC’s. The build standard, hand-wiring & component selection are typically E-H, which is to say they are pretty inconsistent & a bit of a challenge to service at times, but we have to admit it is rather satisfying to get these pedals working properly again, when we can !
