Help Debug an EA Trem

Started by foozertone, October 02, 2007, 05:57:06 PM

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foozertone

Please oh wiser ones please help me sort this out.

1. What I got: I have clear bypass and some kinda "tinny" output with the effect on but no tremelo

2. It's an EA Tremelo from the GGG flashing bypass layou on a GGG PCB

3. I don't know how to post the links for the layout

4. I faithfully followed the suggested layout for the PCB

5. No part substitutes

6. Negative ground (I think)

7. Voltages:
    Batt:9.20
    Brd(red):9.20
    Brd(blk):0.00

    I don't know how to tell which pin is which so here they are top to bottom (sorry)

    Q1:0.76
          1.49
          6.30

     Q2:0.00
           0.00
           0.03

      Q3:0.00
            0.00
            0.03

       Q4:4.32
             1.37
             9.20

I see there's a problem here but I have no idea what to do. Now I turn to you for help

Thanks

Jeff

Paul Perry (Frostwave)

Voltages on Q2 & Q3 obviously very wrong indeed. So something is shorted or connected to the wrong place.

s.r.v.

do you have R6 connected correctly? it is really hard to see the correct position from the layout, and it goes directly to Q2+3

s.r.v.

sorry doesnt affect transistors, looked at the wrong layout

markm

#4
If I had to take a shot in the dark, which this is without more info ( :icon_exclaim:) I'd say there's a solder bridge (or two) somewhere in the vicinity of Q2/Q3 provided all are oriented correctly. Q1 is strange too.....is this a Kit from GGG or just the PCB.

the_random_hero

If you don't know which pin is which, how can you be 100% sure that your pinout is correct? Look up a datasheet for the transistors that you used.
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