[CodeToad]

I got everything soldered nice and did the checks and the "Output jack tip (OL) to IG" shows 176 ohms.

What do I do now?

 

[JamesL]

Is there something wrong? What is it supposed to read?

 

[amb]

The only "path" from OL (or OR) to IG is the sum of R4L and R3L (or R4R and R3R). The opamp itself should not have any resistive path between those two points. Depending on what values you used for these resistors that's what you should measure. If it's not what you expect, then either you got the wrong resistors in there, or there is a partial short circuit somewhere (solder bridge?).

 

[CodeToad]

Here's a few pictures. Maybe someone can see something.

 

[CodeToad]

My bad. I read the process wrong. The incorrect values are on:

U4 pins 7 and 4
U4 pin 7 and IG
Output jack sleeve (OG) to IG

I fried the opamp?

 

[CodeToad]

To be more clear the reading was no ohms between those points.

 

[Lifthanger]

could you post shots of the whole top and bottom?

and to make sure:
0 ohms at
U4 pins 7 and 4
U4 pin 7 and IG
Output jack sleeve (OG) to IG

and just in case: the pins are like that:

8765
1234

 

[amb]

No you want "infinite" ohms reading between those points, not 0 ohms (which would indicate a dead short). Depending on your DMM, infinite could read as "OL" or just "1" (not "1.000").

-Ti

 

[CodeToad]

Thanks for the pin count info....makes a difference.

I got through all the checks now that I understand a little better Thanks for your patience, I'm only slightly dumb and I'll catch on.

The led's do not light up. The long lead goes in the side with the straight line?

Sound comes out in one channel and faintly in the other. ????

 

[Lifthanger]

well I hope you went through the initial check routine. quiescent current did check out well?

the long lead of the LED is the positive end (anode?!) which should go to the pad without the line. just reverse it.

the faint sound could be a bad joint, but someone else might have a better idea.

a shot of the backside could help in that case.

about the pin count - guess how I found out myself

.

 

[CodeToad]

I'm pretty sure I heat treated the lugs on that jack as my first reaction to my first set of wrong assumptions was that it was a bad jack, so I desolder-braided it. Got it squeaky clean before I decided it wasn't the jack and soldered it back. Clusterphuck is my last name.

Ok so I understand now what the checks are doing...looking for shorts right?

I'll just get a few more LED's and install them right this time.

So what temp do you set the iron for these teenie tiny little components? What size tip?
I used a 1.6mm chisel tip but wiping solder seems like it would be easier on those opamps with something smaller.

This is a nice amp Ti, maybe the next one I build won't take me as long

 

[amb]

Your soldering iron tip should be ok with the proper technique. Did you use flux as instructed? Flux is the magic sauce for SMD work. Most of the time I set my soldering station temperature to around 350C for board-level work.

 

[CodeToad]

OK. So I'm only twice as hot as I should be. Heh heh heh.

Yessir, flux is my buddy. otherwise the solder balls up and laughs at me.

Do you think my sound problem is the jack or the reversed led's?

 

[CodeToad]

O you said "C" celsius...so I'm only 50 degrees off...whew.

BTW I've been trying all day to get board level shots but I can't get anything with this usb microscope that isn't fuzzy at that distance.

 

[amb]

Reversed LEDs should not affect the sound. A bad jack certainly would. Did your amp pass ALL initial checks?