Old Foxx Pedal Caps

[Old Blue]

I'm new posting to this forum. I have an old Foxx wah combo pedal that is ill. I want to change the electrolytic caps to restore.

It has the original nine 16V 10mF electrolytics. Question is can I replace the electrolytics with something more durable like ceramics or film, or should I stick with new electrolytics?

This pedal is circa mid 70's and has the fuzz and octave circuits built in..A true classic.
Thanks,
Chris

[Enzo]

The electrolytics are 10 MICRO farad. I have bever seen a ceramic 10uf cap, but it would be immense. Probably pretty microphonic too. 10uf film caps would also be large - the size of things in a speaker crossover.

But why bother anyway? New lytic caps ought to last at least another 30 years anyways, if not much more. They are better now than they were then. And working for 30 some years already isn't bad as it stands. Isn't that enough?

[Mark Hammer]

I'm not so sure that the caps in question need replacement. "Re-capping" is something that is primarily the domain of things like amplifier power supplies, or devices that are older than your Foxx pedal is. certainly if you sense anything is amiss with the pedal, the caps are more likely the culprit than would be the transistors or resistors, but there is little reason to suspect that the caps have been taxed beyond their capabilities over time. If anything, the pots and/or switches will be dirty and worn.

Just what exactly do you mean by "ill" anyways?

[soundmasterg]

Mark, electrolytic caps have a finite lifespan, even when in constant use. If it is sitting on the shelf and not used, it would go bad quicker than in use. Even when in constant use, the dialectric on the inside of the caps dries out, and/or the cap will start physically leaking it out. If they're original, then they should be replaced.

[Old Blue]

The reason I want to change the caps is because this pedal has been sitting dormant for at least 10 years. Although there are no signs of leakage on or around the caps, the wah seems less pronounced than I recall. Also the pedal is very noisy when switched in and out of wah, and in and out of fuzz, which has been a problem with this unit for a long time.

Fuzz works well still. Harmonize effect is questionable, but I suspect the toggle switch is bad, since it has a lot of play in the switch. Need to put a meter on it to tell for sure.

Also picks up radio signals, so I probably have a floating ground somewhere..

As part of the general rebuild, based on what I've read on other web sites, particularly the GEO site, suggests that cap replacement may cure some of these ills.

I was hoping for suggestions on something other than electrolytic, knowing that these do not last for years...

BTW, this pedal did not have a 9V adapter jack. Any thoughts on putting one in? Would it lose value? What would be the best way to tie into the 9V circuit? Could I just wire in parallel to the battery?

I understand electrical theory, and can solder and read meters. Don't know a lot about small capacitors. Currently working on cleaning up the pots and checking for loose connections.

Thanks for any suggestions.
Chris

[Old Blue]

Old Foxx Pedal Caps

The reason I want to change the caps is because this pedal has been sitting dormant for at least 10 years. Although there are no signs of leakage on or around the caps, the wah seems less pronounced than I recall. Also the pedal is very noisy when switched in and out of wah, and in and out of fuzz, which has been a problem with this unit for a long time.

Fuzz works well still. Harmonize effect is questionable, but I suspect the toggle switch is bad, since it has a lot of play in the switch. Need to put a meter on it to tell for sure.

Also picks up radio signals, so I probably have a floating ground somewhere..

As part of the general rebuild, based on what I've read on other web sites, particularly the GEO site, suggests that cap replacement may cure some of these ills.

I was hoping for suggestions on something other than electrolytic, knowing that these do not last for years...

BTW, this pedal did not have a 9V adapter jack. Any thoughts on putting one in? Would it lose value? What would be the best way to tie into the 9V circuit? Could I just wire in parallel to the battery?

I understand electrical theory, and can solder and read meters. Don't know a lot about small capacitors. Currently working on cleaning up the pots and checking for loose connections.

Thanks for any suggestions.
Chris

[Mark Hammer]

Yes caps CAN and DO go bad, but there is a world of difference between the small-to-medium overrated (<22uf,25-35v rating for 9v duty) electrolytics found in most vintage FX pedals, and what happens in amps. Partly its an age thing, partly it's a duty thing, and partly it's a heat thing. Tube amp caps live in a very warm climate, while floor pedals live in a pretty cool climate. These have different impact on drying out over time.

This is not to say that there has never been a vintage pedal that didn't need one or more caps replaced to bring it back to functionality, but ask yourself when was the last time you saw any vintage store, or e-bay sale, or even interviewed big name musician (who can drop big bucks to have Pete Cornish or Bob Bradshaw make them stuff) explicitly indicating that a pedal from the 70's had been recapped or had benefitted from a recap the way they do with amps. I rest my case.

Although I personally find the Foxx Tone Machine (and by extension, Fuzz-wah) to have one of the most robust and pleasing octave-up tones, ANY octave-up fuzz that uses phase-splitting and full-wave rectification will show some unit to unit variation in octave strength based on matching of components in the octave-generation portion. If the fuzz is decent but the octave weak, then that indicates one single cap as a possible culprit, or alternatively a few mismatched components.

In the schematic shown here: http://www.generalguitargadgets.com/diagrams/ftmsc.gif optimal octave-up results from the C4/D2/R10 network providing the same amplitude and signal bandwidth as the C5/D1/R9 network. When the Octave switch is closed and the content from the C5/D1/R9 network is applied, you get octave doubling. Given that this is also only possible if the signal tapped off the emitter from Q2 is equivalent in amplitude to that tapped off the collector. That can often be a function of the matching between R7 and R8. They should be equivalent, and if, as 5% tolerance components, one is 5% higher and the other 5% lower than nominal value, you won't get optimal octave.

Will installing a 9v jack chop the resale value? Depends on a bunch of things, like: how desirable an item it is at the point you choose to sell it, how professional or half-assed a job you do (which also includes location and type of jack as well as simply neatness), how long you are willing to wait for a customer. When it comes to resale value of vintage stuff, some folks are picky about the weirdest things (which is why you can find stores that sell things like "vintage" Pickup selector knobs for $75). Given how much pedalboards have worked their way into the default pro musician setup these days, anyone who has the bucks to spend on shopping for select vintage pedals will likely end up paying someone to install an external power jack for them anyways, so from one perspective you've essentially saved them money and made the item more desirable. That would be a different outcome than changing components construed as having some sort of mojo....like original caps.