GGG Orange Squeezer issue

[lwatford]

Hi, I recently put together my second GGG OSQ, and it's not working. Well, it was working, but now it's not.

I went through the debugging thread, here are the voltages I collected:
Battery = 9.8v
+ voltage @ board = 9.5v
- voltage @ board = 0v

IC1
1 = 8.8v
2 = 8.8v
3 = 0v
4 = 0v
5 = 4.7v
6 = 8.6v
7 = 8.6v
8 = 9.4v

Q1
C = 9.4v
B = 3.5v
E = 2.8v

Q2
C = 1.2v
B = 2.8v
E = 0v

D1
A = 0v
K = 0v
(I'm thinking something happened here. The cathode end looks black. I don't remember how it looked when I put it in)

All the electrolytics seem correct with the exception of C7 on the cathode out of D1. I checked my solder joints and they all seem solid, and I couldn't find any issues with my offboard wiring. It does pass signal in bypass, and the LED lights when the effect is on.

Is it just a case of a burnt Diode? If it was working a few days ago and now it's not what else could be a problem?

Thanks,
Lee

[R.G.]

You know, the reason that "What to do when it doesn't work" lists that stuff about providing links to the layout and schematic you used is so that people who want to help don't have to spend time searching for and maybe finding the wrong info when they're trying to help you. It makes them faster and helps you get help faster. 

[lwatford]

You know, the reason that "What to do when it doesn't work" lists that stuff about providing links to the layout and schematic you used is so that people who want to help don't have to spend time searching for and maybe finding the wrong info when they're trying to help you. It makes them faster and helps you get help faster. 

http://www.generalguitargadgets.com/pdf/ggg_osq_sc.pdf?phpMyAdmin=4a28f86a515b7883e7bc35a68d4e7b6d
http://www.generalguitargadgets.com/pdf/ggg_osq_lo_pot.pdf?phpMyAdmin=4a28f86a515b7883e7bc35a68d4e7b6d
http://www.generalguitargadgets.com/pdf/ggg_osq_instruct.pdf?phpMyAdmin=4a28f86a515b7883e7bc35a68d4e7b6d

[R.G.]

Thanks!
Something is definitely hosed with your IC. Pins 5, 6, and 7 should be sitting at close to 4.7V. Since 6 and 7 are not, it appears that the feedback path that would cause that is open. Check carefully for solder or breakage problems with R9 and R10, and also for the orientation of C5.

Is the IC socketed? And if so, is it inserted correctly?

[Ell]

I built an Orange Squeezer recently. It's a fantastic pedal, I'm sure you love the first one you made.

Unfortunately I can't help you out, but you're from Watford?! I'm from Pinner and I go to school in Watford and spend most of my time there.

[Rig]

If D1 has no voltage on either leg , then one of your caps (C6) may be toast or in backwards. Check to see that the negative side is on the circle shaped landing, and the positive is on the square. The diode being burnt should not affect the voltage on the + side. But make sure the diode is correctly oriented, with the dark band toward the C7.

Tracing back further to  your IC1, you should have half voltage (4.8v) on terminals 6 & 7, but you have 8.6v. The commonality is R9; so you should check that. It's also possible the IC itself is messed up. Those measurements are with the chip in place, I assume.

A transistor with the legs in the wrong place can throw the voltages off at the IC. GGG posted its voltages for NPN transistors having the JFET structure, or in terms of Gate, Source, and Drain, but you are reporting in CBE, as if the transistor were a BJT structure. Why? Could you please transpose those for us so we know which legs you are reading? You might look up the spec sheet for 2N5457 and see if you've got it correct. The Fairchild picture shows the Gate being on the right (in a GSD arrangement), if you're looking at the flat side; and the GGG diagram shows the same thing.

[lwatford]

I built an Orange Squeezer recently. It's a fantastic pedal, I'm sure you love the first one you made.

Unfortunately I can't help you out, but you're from Watford?! I'm from Pinner and I go to school in Watford and spend most of my time there.

haha, no, I'm in the US. it's just my surname. Always hoped to visit Watford some day though.

Thanks for the ideas so far, going to order some replacement parts and check the solder points you all have suggested.

Here's the diode, does it look burnt?

[lwatford]

A transistor with the legs in the wrong place can throw the voltages off at the IC. GGG posted its voltages for NPN transistors having the JFET structure, or in terms of Gate, Source, and Drain, but you are reporting in CBE, as if the transistor were a BJT structure. Why? Could you please transpose those for us so we know which legs you are reading? You might look up the spec sheet for 2N5457 and see if you've got it correct. The Fairchild picture shows the Gate being on the right (in a GSD arrangement), if you're looking at the flat side; and the GGG diagram shows the same thing.

I just wasn't sure if the layout of the trouble shooting guide was standard or not.

q1
G - 3.5v 
S - 2.8v
D - 9.3v

q2
g - 2.8v
s - 0v
d - 1.2v

[Rig]

Yes, that diode looks suspiciously toasted. It could have come that way, but usually the dark band is distinct and not spread out.

Check the value of the R9 you have in there. It should be 220K. I'm looking for Red, Red, Yellow or something like that.

Just for clarity, the transistor readings should be:

Q1:
G 2.4
S 4.0
D 8.8

Q2:
G6
S2.6
D2.6

Q1 is not that far off, but Q2 is really off. Check R5 to see if that's a 2k4.

It's a good idea to check all your values to make sure you got the color codes right. Most of the ones in the phot check out, but I'm not sure about others. The photo is good, but sometimes it's hard to see the colors firsthand even.

[lwatford]

Just a quick thanks for the help. I got my parts today, replaced the diode, touched up a few solder points, and put a socket in for the IC. I actually think the IC might have been a problem all along, since after doing all that, it still didn't work. Swapped in another opamp and it was fine. Guess I might have overheated it somehow.