MXR phase 90 continuous "plopping"

[gorillahuman]

Recently I've bought a blown mxr phase 90; think somebody plugged in the wrong adapter. Anyways; I replaced a diode and both the opamps and it works! The side effect is that now there's a continous plopping going on, even when the effect is turned off. It goes faster once the rate is increased, but below a certain rate it stops.. I've replaced the TL064 with a TL074 but I guess these are interexchangeable.
Any idea where this annoying sound could come from? Thanks!

[Thomeeque]

Is it version with in/out jacks and footswitch connected by wires? Maybe some of these wires now goes close to LFO circuitry, which generates relatively strong electro-magnetic pulses in some cases.. T.

[petemoore]

  Check the data sheets though...
   Isn't the TL064 the low current version of 'that type' of opamp ?
  Say the 074 type is pulling more current and the LFO 'lumps' this current draw from the power supply at the 'lump point' in the LFO sweep, reducing current by using low current opamp as designed [at least in the LFO section] might be the easy way to make it 'plopp' free.

[Mark Hammer]

You're correct about the relative current draw of the 64 vs 74, but it would depend on which part of the circuit we're talking about.  The place where you want the low current draw is for the LFO.  I am unfamiliar with the particular version of the P90 that the O.P. is describing/improving, but if the quad op-amp in question is being used for only the 4 phase shift stages, then swapping a TL064 for a TL074 or an LM324 or an LM837 should make no difference in popping.  The rhythmic popping is current draw from the LFO.

[gorillahuman]

Reviving my own dead thread. I forgot to post that the solution was indeed replacing the TL074 with a TL064 No more popping. Awesome!