EA Tremolo Debug

Blaze · June 28, 2007, 01:21:48 PM

Hi guys. I've just built an EA Tremolo from GGG.com and there is a problem. When the circuit is activated, only the volume knob works. There is only a volume boost no tremolo. The indicator light comes on, but the pulsing LED doesn't(RED Super Bright,tested and it works). The only subs are: 50k pot for volume and I didn't use a PCB, just punch board w/copper backside. I don't have any voltage readings because I don't have my Ohmmeter, but I used an audio probe to trace the circuit and It works up until the Emitter of Q4 and all connections(this is the incoming 9v). Everything is wired up correctly and the True bypass works. Any suggestions?

tonefreak · June 28, 2007, 01:29:18 PM

Q4 could be bad... have you tried replacing it with another?

Blaze · June 28, 2007, 01:47:38 PM

Q4 is fine. I think on another post somebody mentioned that there was possible a wrong pin out on one of the transistors. Any validity to that?

merlin · July 28, 2007, 06:20:14 AM

Hi

i have the same Problem.
Only the Volume works. The tremolo and the lfo led did not work.

Is it possible that there is a bug into the Layout and the PCB layout.
I think that the c3 (elko 22uF) is placed worng. in the ggg_eat_sc_improved.pdf the + of the elko is gone to r5 and r6.
in the ggg_eat_lo_2_led.pdf the + of the elko is gone to Q2.
What is right ?

greetings merlin

merlin · July 28, 2007, 01:00:33 PM

Hi,

i have fixed it.

My EA Tremolo works now perfectly.

I build it with a pcb from "the ggg_eat_lo_2_led.pdf"

The only mistake in thes layout is the polarity of the LFO led.
In the layout the anode (+) goes to C4 and the kathode (-) goes to R8 this is wrong.

I changed the polarity of the LED anode (+) goes to R8 and the kathode (-) goes to C4 and everything works fine.

greetings merlin

markm · July 28, 2007, 01:10:01 PM

Congrats!
If you leave the (+) wired to the board but attach the (-) to the stompswitch, the LED will double as the Status (effect on) LED too.

the_random_hero · July 29, 2007, 03:08:44 AM

Quote from: markm on July 28, 2007, 01:10:01 PM
Congrats!
If you leave the (+) wired to the board but attach the (-) to the stompswitch, the LED will double as the Status (effect on) LED too.

Forgive me if this is a stupid idea, but wouldn't have the speed (closest word I can think of) LED doubling as the indicator LED totally ruin the point? When it's on for the indicator, it won't be flashing?
Chances are this is a stupid statement, but I never got mine working

markm · July 29, 2007, 07:53:22 AM

No.
It never lights up solid.
When the effect is on, the LED blinks at whatever tempo the speed is set.
When the unit is off, the LED is off.
If wired in the way that ROG shows in their schem or the way GGG has it, the LED will flash the tempo whether the effect
is engaged or not......it's just always flashing.
Savvy?

the_random_hero · July 29, 2007, 04:50:59 PM

Quote from: markm on July 29, 2007, 07:53:22 AM
No.
It never lights up solid.
When the effect is on, the LED blinks at whatever tempo the speed is set.
When the unit is off, the LED is off.
If wired in the way that ROG shows in their schem or the way GGG has it, the LED will flash the tempo whether the effect
is engaged or not......it's just always flashing.
Savvy?

Aha! I'm with you now. I was lead to believe that the indicator LED's function was to turn on when the board was on, not off when it's off. Thanks for clarifying that for me.
Now if I could only get mine to work....

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EA Tremolo Debug