I built a PT80, works fine.
Proceded with the following mod:
http://www.moosapotamus.com/pt80delay/PT80effectloop.gif
(for ref. PT80 Schemo: http://www.generalguitargadgets.com/v2/diagrams/pt80schem.pdf)
Now, I know i've got it wired correctly as with nothign in the send, the toggle doesn't matter. With the send plugged in (nothing in return), I toggle between delayed or original sound.
When I put in a pedal (eg. Zombie Chorus) in the effects loop on bypass, everything works fine. But once I engaged the effect in the effects loop, it'll squeek like mad ! I tried a Boss Overdrive/Distortion pedal, and the same happened. Interesting fact: the frequency of th squeek is the becomes higher when the level on the overdrive is turned up.
hmm..
for the 1uF that goes into the compander, I used a polyster film one instead of a electrolytic one (well, the schemo didn't say electrolytic, but the layout did). Could this be the problem ?
thanks
Han
well
didn't connect the ground of efx loop to the circuit ground.
(was working with the guts only)
once i did.
boy did it rock !
:)
Han