Cue forward to 2020. My former classmate is enjoying his retirement, the pedal-dumping friend is now a former friend I haven't spoken to in years (because of Facebook radicalisation, I hasten to add), and on my first visit to a favourite pawnshop after the easing of Covid-19 lockdown I saw this on display:
It was a faithful-looking reissue of the Ibanez auto filter, sold and branded by the pedal's original manufacturer! The shop only wanted $99 for it, but it was clear that it had at least one issue...
That issue would be very easy to fix with a nut and washer from a donor 1/4" jack, and the sales person offering it to me for $80 made the deal a no-brainer.
I couldn't wait to get it home and test it. When I plugged it in, however, I found that the circuit (and the indicator light) would only engage when the pedal foot switch was pressed to its limits, and would not latch on so that releasing foot pressure would cause the pedal to revert to bypass. I figured that the pedal's switching logic had failed, but what I found demonstrated both that some things are best left in the past, and that messing with the formula can be a terrible idea.
Doing a Google search of forums showed that modern Maxon pedals tended to have switching failure which locked them into the engaged mode, and that unlike their antecedents they were true bypass (ie mechanical switching, not logic). Where people had not hacked conventional heavy duty foot switches onto the enclosures as a solution, the recommendation was to replace the switch. Maybe the switch's return spring had broken? I plucked up the courage to take a look.
I found that despite their tank-like casing, the build quality of this recently-built pedal is still very much 1980 second-tier Japanese manufacturer, with phenolic boards containing through-hole carbon film resistors sitting on their ends connected by a mess of light-duty wire. Fittingly the battery compartment is only separated from the foot switch carrier board by a flimsy piece of plastic covered in a thin layer of foam.
(Note the hilariously un-1980 main body screws, not just Torx, but tamper-proof Torx! FFS-did Apple refuse to sell them pentalobe screws?? Memo to fellow manufacturers-this sort of shenanigans is not going to stop anyone from ordering a suitable driver set from Amazon to hack the product, just make life inconvenient for anyone attempting field repairs)
I unscrewed the switch panel and pulled it back through the mount hole to reveal the switch. Not only did the switch click in and out nicely when I pressed it directly, but the pedal switched between engaged and bypass modes without any problems. Clearly there had to be a problem somewhere else.
Hmmm, let's look at the mechanical linkage to the foot pedal movement then. A block of foam rubber on the underside of the pedal surface. OMG! Foam rubber, which can permanently compress under sustained pressure, and loses resilience with age. Seriously???
Well, that explained the switch not pushing in far enough to latch, but what of the switch not budging at all when engaged? Like a lot of changeover pushbuttons, the switch shaft stays lower when actuated as a visual indicator-which means that disengaging it requires a deeper push, which the foam block was not capable of. This would not have been so much a design concern in the 80s original, where a simple momentary pushbutton was used for electronic switching, as the action would have been shallow and identical either direction, but the current mania for "true bypass" circuits necessitates a changeover switch with relatively deep, asymmetrical action, and the foam block is not up to the task. Evidently no-one at Maxon thought of that when "improving" the design.
I chose to re-insert the switch in "on" mode so at least the pedal is useful for now, but I will be trying to layer gaffa tape onto the foam block to better distribute pressure across its surface and to try and get the foot switch working. More to come!
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