Polytone no Vibrato

[drewl]

UREEKA

Power supplies were kinda' low, around +/-14v, so I replaced the flimsy series pass transistors and zeners, no change.


okay, well the 301 for the oscillator was weak so I was using a 5534. I tried a 741 and UREEKA, oscillator runs on it's own as it should.

Everything looks great on the bench using nice clean power supply for the +/- 24v.

Channel one was giving me some hum with the power amp's supply, we'll see if it's still there when I get home.

[Jon Snell]

Good news. Well I suppose the circuit would have been based around the 709/741 era of op amps. Lots of open ended gain is required.
Funny how it is always the last component to be changed that was the culprit.

[drewl]

Okay, figured out the ch1 hum.
U1 pin 5 was not grounded.
Trace was either cut, or damaged by chassis screw.

But.... Back to the tremolo.
It works, has some tick, but when you open the foot switch jack, it tics louder and faster!

Term turns of but it tics more.

Any ideas?

[drewl]

Ah screw it.
turn intensity down a bit, no tic and plenty of tremolo and no tic when switched off.

[Jon Snell]

Adjust the 2k5 preset for less ticking at high intensity setting.

[drewl]

Tried that, not enough range.

Like I said, turn intensity down a bit and tic goes away with plenty of tremolo.

I'll tell him it's a built in metronome for practicing!