Input signal clipping, need to clean it up...

[Rob Strand]

If you short Drain and Source on Q3, does the clipping go away? If not, it's not Q3.

Without trying that Q3 short test you are pretty much wasting your time.   If the JFET in the circuit really is a J113 (it might not be) it should work find without clipping.

I'm of course assuming the clipping problem is in Effects mode and not Bypassed mode.

[iainpunk]

i recommend you grab an audio probe and check where the distortion starts, i honestly doubt its that first transistor.
cheers

i just want to re-state this:
i honestly doubt its that first transistor.
maybe check with an audio probe where in the circuit the distortion ACTUALLY starts

cheers, Iain

[antonis]

i honestly doubt its that first transistor.

Could you plz keep your opinion to yourself, Iain..??

P.S.
Late night with aged tsipouro here..

[Vesperado]

Appreciate the feedback, gents.

Next time I get into the FX68 I will bypass Q3 and raise the Vbias to see what happens. The audio probe is a good suggestion. I agree, I do not think Q5 is culprit here, although I suspected it at the beginning.

The pedal is useable now, yet at any rate it wouldn't hurt to get a non-clipping signal at headroom...and preferable, no doubt.

[Vesperado]

And while I'm in there I might replace the stock TL062, or cut the trace and lower the Vbias with a trimmer there. It is the only other place I can think of...

[Vesperado]

Replaced the TL062 on the FX68, which removed the clipping. I have Vbias now set to 7.6V and Q5 at 7V. Good headroom, nice chime

Before disturbing the transistor on the 460 I will replace the ICs first. Probably all it needs...