madbeanpedals::forum

Reflowed all my solder, and went thru the schematic about 5 times.

Getting strange voltages on my stage fright.  Replaced TL074 with a new IC, still no love.  My rate LED doesnt light up, but when I touch any probe to pin 5 of the TL074 IC1, it begins to strobe.  Any ideas?

Voltage: 9.54

IC1

1   1.51
2   1.51
3   1.32
4   9.30
5   4.66      
6   1.42
7   1.42
8   1.52
9   1.40
10   1.38
11   0
12   1.41
13   1.52
14   1.52

Just wanted to post the full voltages, If you guys have any ideas of why im getting such low voltages I would appreciate it!

Thanks

Voltage: 9.54

IC1

1   1.51
2   1.51
3   1.32
4   9.30
5   4.66      
6   1.42
7   1.42
8   1.52
9   1.40
10   1.38
11   0
12   1.41
13   1.52
14   1.52

IC2

1   8.72
2   1.41
3   2.62
4   0
5   1.42
6   8.69
7   0.621
8   9.34

IC3

1   1.21
2   0.157
3   1.42
4   1.42
5   2.36
6   0
7   2.36
8   1.33
9   1.54
10   2.58
11   9.33
12   2.58
13   1.42
14   1.42
15   0.18
16   1.21

IC4

1   1.21
2   0.223
3   1.42
4   1.42
5   2.55
6   0
7   2.55
8   1.51
9   1.31
10   2.33
11   9.32
12   2.33
13   1.42
14   1.42
15   0.231
16   1.21

IC5

1   1.21
2   0.20
3   1.42
4   1.42
5   2.35
6   0
7   2.35
8   1.32
9   1.52
10   2.57
11   9.32
12   2.57
13   1.42
14   1.42
15   0.23
16   1.21

Try this - remove IC1. Now measure the voltage on pin5 in the socket. Are you getting 4.5v there? If not, R53 or R54 is the problem. If you do get 4.5v there and then it drops when you re-insert IC1, then something connected to the VB rail is off (refer to the schematic for all the components connected to VB).

Quote from: madbean on August 01, 2017, 02:10:19 PM
Try this - remove IC1. Now measure the voltage on pin5 in the socket. Are you getting 4.5v there? If not, R53 or R54 is the problem. If you do get 4.5v there and then it drops when you re-insert IC1, then something connected to the VB rail is off (refer to the schematic for all the components connected to VB).

(https://uploads.tapatalk-cdn.com/20170802/c1172ceb4bb6ba3a51d88c402b0fe0aa.jpg)
Thank you for taking the time to help!

After pulling out the IC and looking at everything one more time with a magnifying loop.  I found the culprit to be, just my luck, a faulty hole in the IC socket

Pulled the old one out and replaced it, and it fired right up! Thanks for the help




Sent from my iPhone using Tapatalk

Its all about the leaf sockets.

Your absolutely right!.. Wouldve saved me a week of mind boggling brain fry!

With machined pin sockets, I've found it's best to either go super-spendy, or to not bother and get leaf sockets.

Plus most ICs have square legs, so they make more contact than they do in round holes :)

Quote from: alanp on August 02, 2017, 05:24:02 PM
With machined pin sockets, I've found it's best to either go super-spendy, or to not bother and get leaf sockets.

Plus most ICs have square legs, so they make more contact than they do in round holes :)

Another ring of knowledge added to my chain.

I mean, if I had some circuit I know I would be taking an IC in and out of all the time, yeah, get a good machined socket. But we pretty much just use them for the off change we get a bad chip. So, the chances of actually wearing out a leaf socket in those circumstances are pretty much zero. Plus, leaf sockets cost pennies.

Quote from: Zigcat on August 02, 2017, 10:13:38 PM
I mean, if I had some circuit I know I would be taking an IC in and out of all the time, yeah, get a good machined socket. But we pretty much just use them for the off change we get a bad chip. So, the chances of actually wearing out a leaf socket in those circumstances are pretty much zero. Plus, leaf sockets cost pennies.

I'm in Flint Michigan , I had to use what I had laying around, but never again! lol I wasted a week trying to figure out where I went wrong.

Thanks for the tips!