Boss PH-2 volume drop

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Pepe
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Re: Boss PH-2 volume drop

Post by Pepe » Wed Apr 05, 2023 12:03 pm

May it be that it only needs a proper calibration?
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laurie
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Re: Boss PH-2 volume drop

Post by laurie » Thu Apr 06, 2023 11:22 am

There is only one trimpot - it is on the VR board and it controls the voltage on pin 9 of the IR3109 chip. But it is unclear to me whether mis-adjustment of this trimpot would result in a voltage drop. The function of the IR3109 is difficult to understand - it is Roland proprietary and not much info is available.

It would be worth marking the trimpot and then adjusting it to see if it changes the output volume.

I'm also interested to hear about the leaking capacitors - were they physically leaking? Or did they have a high ESR?

stevenrb718
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Re: Boss PH-2 volume drop

Post by stevenrb718 » Thu Apr 06, 2023 7:51 pm

I believe the trimpot is to dial-in the oscillation. I'm not messing with that as the timing of the pedal is perfect. The capacitors were physically leaking their acid. The 570N is also not at fault.

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