[Eisenhower]

I finished assembling my cmoy (standard layout with 470uf caps and with a rail splitter for the virtual ground), and when I hook my 9v battery up, the LED comes on (although quite very dim) and the opamp gets very hot, too hot to touch.
How should I troubleshoot shoot this?

 

[The Monkey]

have you gone here, yet?

Also, post some pics.

You might also want to try swapping out the opamp, but if it's getting that hot, let's see some pics first.

Are you getting any sound?

 

[FallenAngel]

First check DC offsets and current draw. Check Tangent's troubleshooting article.

Damn Monkey, beat me by 2 seconds

 

[thedoctor]

Quote:

Originally Posted by The Monkey You might also want to try swapping out the opamp, but if it's getting that hot, let's see some pics first.

^ and use some cheap, easily available Opamp to try it out with. most probably it will get burned, along with the last Opamp that you've used.

don't wanna burn some expensive Opamp now do you? use some TL072/TL082 or other jellybean chips.

 

[Eisenhower]

Here are some pics:




I left some leads still on /\
On the opamp socket, one of the inputs got quite hot when I was soldering and melted the surrounding plastic, I checked it with a DMM and it seems fine



If you need better pics let me know, I will go through tangents troubleshooting guide soon.

 

[dokebi]

Your tle is wired incorrectly.

 

[Pars]

First apparent problem is you have the socket in backwards (the notch should be pointing down, not up as you have it). If you plugged the opamp in with pin 1 up (as your socket is) you toasted it, and that would explain the heat.

 

[Eisenhower]

Quote:

Originally Posted by Pars First apparent problem is you have the socket in backwards (the notch should be pointing down, not up as you have it). If you plugged the opamp in with pin 1 up (as your socket is) you toasted it, and that would explain the heat.

I was under the assumption that the socket direction was not important?
also, like I said, I think the pin that melted on the socket is still functional.

 

[Eisenhower]

Quote:

Originally Posted by dokebi Your tle is wired incorrectly.

How should it be wired then?

 

[firefox360]

Quote:

Originally Posted by Eisenhower I was under the assumption that the socket direction was not important? also, like I said, I think the pin that melted on the socket is still functional.

Well the socket direction isn't that much of an importance, it's only there to guide you in inserting the OP-Amp. The semi-circular notch in the opamp and socket is suppose to be oriented downwards accordingly to the Tangent Cmoy instructions. If you oriented it the wrong way you basically are sending V+ to V- (and vice versa) on the op-amp. Also as someone else said, you might have wired your TLE2426 wrong. Not to sure about that, but you should check it nonetheless.

 

[Teerawit]

Quote:

Originally Posted by FallenAngel First check DC offsets and current draw.

Don't do this, as there's obviously something wrong with the circuit, and by the time you make these measurements you'd probably fry your opamp.

Quote:

Originally Posted by Eisenhower I was under the assumption that the socket direction was not important? also, like I said, I think the pin that melted on the socket is still functional.

The direction of the socket isn't crucial, but it's an important marker to tell you how to properly align your opamp. Too late now, but you can still work around it by remembering to insert the opamp OPPOSITE to the notch on the socket.

 

[The Monkey]

Quote:

Originally Posted by Eisenhower How should it be wired then?

I can't really see if the tle is wrong but confirm by checking here, and then check the TLE datasheet.

 

[Fiola]

if you check the tl2426 specification, http://focus.ti.com/lit/ds/symlink/tle2426.pdf
you'll see that the pin looking from the flat side goes like
out-common-in
the thing is, the common is not the common ground in your circuit, it's actually suppose to be the -V. you have it currently hooked up to your ground, and your out hooked up to your -V or something.

 

[Pars]

Yeah, you're TLE is wired incorrectly.

Quote:

Originally Posted by Eisenhower I was under the assumption that the socket direction was not important? also, like I said, I think the pin that melted on the socket is still functional.

We all know about assumptions

. Regarding the socket, yeah the notch is just a guide, but really, do it right. What if you pass the amp on to someone (or sell it)? Sockets are what, 50 cents? Replace it.

Also, it appears that your right electrolyic cap may be incorrect polarity. Make sure the polarity on both electrolytics is correct.

Did you bother reading Tangent's guide? Do you have a meter (DMM)? Did you check your voltages or just slap stuff together and fire it up? A little effort on your part before hopping up here and asking for help will go a long way.

 

[Eisenhower]

I fixed the tle and mounted the opamp correctly, nothing gets hot anymore

But, I tried hooking up a pcdp and a pair of cheapo headphones like tangents guide said and when the battery isnt hooked up, it sounds like just a pcdp, but when the battery is hooked up, the signal gets very faint and crackley.