extremely low level on PH2

G Kresge · June 24, 2005, 02:14:10 AM

I realize this forum is primarily based on posts by people that are builders, but there seem to be quite a few debugging threads too.

I have a Boss PH2 phaser that's causing problems. In bypass mode, my signal is of course normal, but when the effect is engaged, there is almost no sound at all. I'm running it from an adapter that is brand new. Does anyone know what would cause this? Thank you.

MartyMart · June 24, 2005, 04:23:05 AM

Try and locate the pair of "switching fets" usually 2SC1815/2SK30A's in
Boss/Ibanez circuits.
They will connect through some caps/resistors to the foot switch cables...
I've had a few pedals go "bad" and a new pair has fixed a couple.
That would cause the exact same effect, as the "FX" sound is not
switching "on" but bypass is ... !
Thats presuming that you have a very "faint" but working "Phaser"
sound though .. ??

Marty.

G Kresge · June 24, 2005, 03:45:02 PM

That sounds about right. There is some audible pahsing but it is incredibly low in volume. I'll investiget that option. Thanks Marty!

G Kresge · June 24, 2005, 10:29:09 PM

Well, it wasn't the switching FETs. I replaced them and still get the same thing out of it. It's sometimes a faint phasing effect, but most times a faint crackling swirly sound. Like a very fast rate setting that's crackling.

Any thoughts anyone?

G Kresge · June 25, 2005, 02:21:19 AM

I adjusted the trimpot attached to the "RES" pot and the crackling is gone, but still ridiculously low level coming out of the damn thing.

MartyMart · June 26, 2005, 06:07:34 AM

Hmm,
OK, that guess was off .... is there an output op-amp or transistor that
could be down, that's just reducing the out volume ... ?
I dont have a schem here ....

Marty.

G Kresge · June 26, 2005, 06:45:52 AM

Haven't been able to locate a schematic, but I'm still looking. Thanks Marty.

Vsat · June 26, 2005, 10:00:53 AM

What integrated circuits are being used for the phasing? LM13600? CA3080? Or a Roland custom chip?
Regards, Mike

Arno van der Heijden · June 26, 2005, 10:18:16 AM

What kind of adapter are you using?
I think this is one of the older style Boss pedals that might need an unregulated 9 V adapter, or a 12 V regulated one.

G Kresge · June 26, 2005, 06:24:14 PM

It does the same thing with a battery, so I don't think it's the adapter. Thanks for that though.

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extremely low level on PH2