Leach Amp Issues (HELP!)

[VictorG]

Hi Guys-

I turn to you once again in my time of need for expert advise. I have built up two leach boards but am getting less than desired results. I am only getting about a gain of 3 (on my cleanest signal.)where I should be getting ~21. Further, the signal is distorted. I am expieriencing tons of offset both with and without signal. I am going to present views of each output signal along with the intput signal in hopes that you experts will give me clues on where to start checking. All pics listed below are found in the zip file attached.

I have two boards, which are called L and R for where they sit on a common board.

The signal image was the signal for all tests, attached as: singal1.jpeg

I will now outline inputs for each of the Pics in the L seris.

First, the R Seris, the current draw is on the vcc line, and the -vcc typically showed a draw of 1/3 the vcc draw. Nasty Offset, the characteristics of my sign wave change in how much is being clipped. The odd thing is I have to have an "inbalance" between the vcc and -vcc to get any signal. When they are equal, I get no output signal, or at least nothing great. I prefer advice on this board as it seems closer to ideal. If I can get one right, maybe i can trouble shoot the other.

R-0.jpeg (offset w/ no signal: 3.75V )
vcc: 9V
-vcc: -7V
current draw: 3ma

R-1.jpeg (offset w/ no signal: 9V )
vcc: 10V
-vcc: -7V
current draw: 3.5ma

R-2.jpeg (offset w/ no signal: didnt take )
vcc: 10V
-vcc: -12V
current draw: 4ma

R-3.jpeg (offset w/ no signal: 11.25V )
vcc: 12V
-vcc: -20V
current draw: 6ma


Now the L seris, these guys are not as pretty as the pic indicates. Again, the current draw is on the vcc line, and the -vcc typically showed a draw of 1/3 the vcc draw. Same "inbalance"

L-0.jpeg (offset w/ no signal: 13.44 )
vcc: 14V
-vcc: -11V
current draw: 7ma

L-1.jpeg (offset w/ no signal: 11.25 )
vcc: 12V
-vcc: -20V
current draw: 7ma

L-2.jpeg (offset w/ no signal: 14.22 )
vcc: 15V
-vcc: -9V
current draw: 8ma

L-3.jpeg (offset w/ no signal: 24.06 )
vcc: 25V
-vcc: -9V
current draw: 15ma


So those are the pics, let me know where you guys think I need to be looking for my problems. The odd thing is my friend found similar problems in one of his boards (which we made together) as my L seris board. He was never able to rectify the situation... I would prefer not to solve this problem by a all out redo including the boards. I checked my board layouts ect against a pic of his working board.

Thanks Guys, Brian

[djk]

check your input ground

[VictorG]

one last note, the graph of L03 is only looks cool because i made the x axis origin at 20V so i could see the signal.....

[Tony]

if you stuffed your boards right, and wired them up correctly, grounding included, you should not be getting those offsets...if i were your i'd work those boards one at a time....