DOD '77 build problem (I have voltages)

Started by svstee, February 28, 2009, 02:04:07 PM

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svstee

Built a DOD '77 overdrive off of this layout here
http://aronnelson.com/gallery/main.php/v/ulysses/ulysses_layouts/ulysses_77_grey_dod_od_250/ulysses_77_grey_dod_od_250_1_0.gif.html
I scrunched everything closer together because it seemed like there was a lot of wasted space on that layout. I built it and it works, but it has a nasty gating effect. When I play hard it does what it is supposes to, put if I pick softly or let a note sustain it gates and sound really bad. Voltages, with a battery that measured 9.13

IC 1
p1: 0.00
p2: 4.43
p3: 2.19
p4: 0.00
p5: 0.00
p6: 9.01
p7: 1.96
p8: 0.00

The polarized cap has 1.67v on + side and 0.00v on -.
Any clues?

oskar

The voltage readings doesn't make sense really. You've got 4.5V on pin 2 which is good and should be the same as pin 6... which reads 9V...?
Redo!!!
Please take new DC readings on the IC and also on the board mark a3 (Vb)which should read ~4.5V.
The Tonepad, Mas Distortion has a 10u cap from Vb to ground. Try and add this as it sounds you're having trouble with the OP bias. But first ensure you have 4.5V for the Vb. You can also try and add a small cap across R5(~10-47p).