Just fixed my Ibanez TS-808 pedal.

[Simon Barden]

Have a look at the old cap and see if it's got any voltage value on it. Caps can go short or partially short-circuit if their voltage rating is exceeded. They might have used a cap with too low a voltage rating. That cap is there to take any voltage spike, caused by the foot switch, to ground. DC is a lot worse at causing switching spikes than AC and they normally occur on break of circuit when you get a very brief arc as the current continues to flow until the air gap gets too large to sustain it. The switching spike can be many times greater than the switched circuit voltage, so unless the replacement cap has a decent voltage rating, it's likely to occur again over time.

[DrNomis_44]

Have a look at the old cap and see if it's got any voltage value on it. Caps can go short or partially short-circuit if their voltage rating is exceeded. They might have used a cap with too low a voltage rating. That cap is there to take any voltage spike, caused by the foot switch, to ground. DC is a lot worse at causing switching spikes than AC and they normally occur on break of circuit when you get a very brief arc as the current continues to flow until the air gap gets too large to sustain it. The switching spike can be many times greater than the switched circuit voltage, so unless the replacement cap has a decent voltage rating, it's likely to occur again over time.

That's a very valid point, the pedal itself only runs on +9V DC, and I'm guessing that the voltage-rating of those small disc ceramic caps is about 50V DC or so, as far as I can make out with my eyes alone, there is no marking on the cap indicating it's voltage rating, other than the three-digit marking indicating it's capacitance value, the replacement cap has a DC voltage rating of 100V DC so I think that it should be more than enough, now that you mention it, I was using a Switchmode Power Supply to power the pedal at one point before I noticed the footswitching issue, the Switchmode Power supply was designed to put out 18V DC at 2A, but, it was plugged into a small box that regulated the 18V DC down to +9V DC, and the pedal was getting regulated +9V DC.

It's possible that the ceramic dielectric of that ceramic cap may have gotten punctured by a spike coming from the Switchmode Power supply, but then again if that actually did happen then that would have taken-out all the other caps and the JRC4558D Op Amp IC too, I'm thinking that somehow the faulty cap might have suffered from moisture ingress, since the weather has been a bit humid and wet lately, and the moisture ingress is responsible for the 1.8M resistance reading I got, well it's about the best theory I can come up with so far, as a side note, I noticed that the cap seemed to be a bit temperature-sensitive too, desoldering it from the circuit board seemed to temporarily make it come good...how's that for a weird one?