Need Help With Buffer Problem!

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 9:17 am

I have just yesterday built myself a standalone opamp buffer fro the beavis page.

But as i tried it out, it wasn't what i expected. as i plucked harder and harder, it was more like the worst overdrive you could imagine.
The IC is in a socket so no melt down there, but could i have fried a capacitor? I'm quite shure the traces are ok and my soldering is good, as i cheked it with my DMM.

Hope you can help me

cheers

timhulio · Post by **timhulio** » Wed Aug 24, 2011 9:45 am

Hmmm. I'd have said check yer solder joints.

This thing fuzzes out when power is low, so check it's getting 8-9V. Prolly best post a pic (macro setting!) and let the dog see the rabbit.

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 10:05 am

I'll send pictures in a minute.

I just cheked the thing again, and i began to doubt my power connection. This thing is just runing of a power supply, so therefore no batery connection. So i wired the thing like:

There are three connections on the back. One that is connected to the pin, and two others connected to the side. I connected the ground wire to the pin connector, and the "hot" wire from the side connection to the 9v imput. is this right, because i thought it seemed weird, but on all wiring schems i saw, it was connected this way,

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 10:23 am

Here are pictures of top and bottom of board:

Hope they can clerify..

timhulio · Post by **timhulio** » Wed Aug 24, 2011 10:38 am

Some of those traces have got to be bridged. Did you check them with a multimeter?

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 10:53 am

Yes i did. Multiple times, they're all fine. Could i have fried the 100 nf cap? thats the only one that might have gotten to much heat.

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 10:58 am

I use a TL072IP chip. Could that be the problem? isn't it just a low noise version of the TL072?

timhulio · Post by **timhulio** » Wed Aug 24, 2011 11:28 am

Nah that chip should be fine.

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 12:02 pm

I'll redo them and see if it works.

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 1:08 pm

nothing.. i swaped the 100 nf, and now its totaly dead. (: fuck.

alpeperker · Post by **alpeperker** » Wed Aug 24, 2011 2:45 pm

But thanks for your help! I really apreciate it!

I think i'll try to start from scratch with this one.