removing oscillation from a PT-80

Started by powerplayj, September 29, 2005, 06:39:14 PM

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powerplayj

http://www.generalguitargadgets.com/diagrams/pt80lo.gif


I get oscillation at the very end of the "repeats" pot rotation.  I switched from a 50k to 25k pot and still get the repeats.  First, is th pot wired so that the max repeats actually occurs at 0 ohms instead of 50k (the reverse of what I am assuming)?  Where should I be making adjustments to eliminate the oscillation? 
builds completed: boutique fuzz, rangemaster, BSIAB2, PT-80, Tonepad wah, Ross Comp, Axis Fuzz, MOSFET boost, Thunderchief, Big Muff (triangle), Mr. EQ, Dr. Boogey,  Neovibe, Dist+, EA Tremelo, ADA Flanger, RM Octavia
next build(s): ???

rody82

I think you mean that never-ending, sometimes getting louder and louder and stranger and stranger sounds?  Well, i just love them  ;D Try to find that sweet spot when its just starting and then play with those other knobs, especially time...

As far as i understand, the repeats pot is something like a feedback pot, you can adjust how much part of the signal gets back and played again. If its too much, you'll get something like the feedback on amps... So what you hear is normal... :)

If you hate that, try to insert some resistors on the repeat pot at lug 2. (maybe lug3?)

rody82

Oh, i have one question too..  :)

How can it be possible, that my PT80 sometimes works perfectly sometimes only "no delay" mode?
I mean i connect the 18V and start playing.. If its not working (no delay sounds),
i have to disconnect and reconnect the DC plug, and after 1-2 tries its ok. After that, no problem
till next time. Strange.


rody82

No idea about my question? Why i have to "reset" it sometimes to work?

powerplayj

Quote from: rody82 on September 30, 2005, 10:32:29 AM
Oh, i have one question too..  :)

How can it be possible, that my PT80 sometimes works perfectly sometimes only "no delay" mode?
I mean i connect the 18V and start playing.. If its not working (no delay sounds),
i have to disconnect and reconnect the DC plug, and after 1-2 tries its ok. After that, no problem
till next time. Strange.


hmmmmm....  I have never had that problem????
builds completed: boutique fuzz, rangemaster, BSIAB2, PT-80, Tonepad wah, Ross Comp, Axis Fuzz, MOSFET boost, Thunderchief, Big Muff (triangle), Mr. EQ, Dr. Boogey,  Neovibe, Dist+, EA Tremelo, ADA Flanger, RM Octavia
next build(s): ???