BOSS PH1R PHASER......mod for the volume boost?

[fenderiarhs]

I have a Boss PH1R phaser and while i like the sound of it i hate the fact every time i use it there is a noticeable volume boost. Do you know of any mod that can cure the problem?

[fenderiarhs]

anyone?

I found a photo of the pcb.........there's something that looks like a trimmer in the botom left of the circuit



would that regulate the output of the pedal?

[MartyMart]

I'm not 100% sure but it may be a "balance" for the phase section.
I don't have one anymore so can't help, you could just add an "R" to ground from the output
to attenuate a little ?
MM.

[Mark Hammer]

It is a FET-based phaser which means that there is a 99.9% likelihod the trimpot is for biasing the FETs.  Since the two dual op-amps on the lower right are identical in their component complement and have FETs sitting beside them, it is a sure thing that those two are your 4 phase shift stages.  The chip on the upper left is a TL022 which makes it your LFO section.  That leaves the dual op-amp on the upper right as your input buffer/splitter and mixer/output stage.

It is VERY common practice to "bypass" such pedals simply by cancelling/lifting the wet signal at the point where wet and dry mix together to produce the phase-shift effect.  The cancelling/lifting is done with a single FET.  My guess is that the transistor waaaaaayyyyy up in the right hand corner is such a FET.  If so, it will likely be a 2SK30A or 2SJ184 or something like that (the number shown will start with a J or K).  One of the pins of that FET will go to a small-to-medium value resistor (let's say between 10k and 100k), which in turn will likely go to pin 2 or 6 of that chip (the inverting input).  Once you identify which "side" of the 4558 it goes to, there will be a resistor straddling either pins 2 and 1, or pins 6 and 7.  That resistor will set the gain of output stage.  If you find it too loud, you can reduce the value of that resistor a bit.  So, if it was, say, 100k, you could consider replacing it with a 91k or 82k resistor.  Alternatively, you can solder a 2nd resistor in parallel on the copper side of the board to produce some specific parallel resistance value (e.g., a 680k parallel resistance plus a 100k unit on the board itself would get you 87k).  Higher resistance values get you more gain/output, lower values get you less.