Newbie, building Orange Squeezer compressor

[remow]

Hello all, I'm new here and I thought I would try to get an answer to my problem.  I'm building an Orange Squeezer and have come to this problem:  When the box is bypassed I get the signal from the guitar no problem, when the pedal is switched on I lose the signal.  My LED lights just fine and turning the volume pot will increase/decrease a slight hiss from the pedal.

Any ideas?

[Craig V]

Play with the trim pots.  If you still don't get anything, consider building an audio probe.

[MarkB]

Go through the debug FAQ - most of that stuff is REAL helpful.

Throw together an audio probe.. don't even need to build one - just use alligator clips, a small cap and a spare jack - that will tell you a LOT.

Use a DMM and measure throughout the circuit.. post voltages of key spots (in the case of the OS - the JFETs).. and look for shorts in your board (or perf?).

A few useful bits of info from you would help, also..
PCB or perf?
which layout did you use?
what FETs did you use?

"-)

[remow]

I used a PCB from General Guitar Gadgets:
http://www.generalguitargadgets.com/v2/index.php?option=displaypage&Itemid=79&op=page&SubMenu=

This is the layout I used:
http://www.generalguitargadgets.com/v2/diagrams/orangesqueezer_lo2.gif
Note: I used a DPDT rather than a 3PDT switch.

I used 2N5457.

Thanks.

[MarkB]

OK - that's a start.. same layout/PCB and JFETs that I used.

measure the voltages on the FETs... and test for continuity where there shouldn't be any.  

One trick is to measure across components.. you should see resistance on most, if not all.. if you see nothing - open - you have a short.

Also - check for continuity between +9 and ground in various places.. make sure you're not shorting to ground.
"-)

[Mark Hammer]

1) Are you sure the op-amp is installed properly?  e.g., it might not be seated properly if you have it in a socket, or it may be facing the wrong way such that you have pins 1 and 8 where pins 4 and 5 ought to be.

2) Are you sure the IC is receiving power?  Are you measuring +9v where you ought to?

3) Are you sure that any and all polarized capacitors are facing the right way?  There is a 4u7 cap on the output of the op-amp.  The "+" side should be at the output pin, and the "-" side should be facing the volume pot.

4) Have you used the wrong pinout?  Possibly mistaking a 741-type (single op-amp in an 8-pin DIP) pinout for a 4558-type (dual op-amp in an 8-pin DIP) pinout?

[remow]

I finally got a multimeter but I'm afraid it brought more questions than answers.  I have the Sperry DM-350A pictured here:


To answer some questions:
1) Are you sure the op-amp is installed properly? e.g., it might not be seated properly if you have it in a socket, or it may be facing the wrong way such that you have pins 1 and 8 where pins 4 and 5 ought to be.
Yes it is in correctly and is seated fine.  I checked this twice it looks good.

2) Are you sure the IC is receiving power? Are you measuring +9v where you ought to?
This I am not sure.  How do I measure this with the multimeter?

3) Are you sure that any and all polarized capacitors are facing the right way? There is a 4u7 cap on the output of the op-amp. The "+" side should be at the output pin, and the "-" side should be facing the volume pot.
I believe these are all in correctly.  I checked them (arrow pointing to negative lead) and all looks correct.

4) Have you used the wrong pinout? Possibly mistaking a 741-type (single op-amp in an 8-pin DIP) pinout for a 4558-type (dual op-amp in an 8-pin DIP) pinout?
No, the op-amp is correct and in correctly.

5)measure the voltages on the FETs... and test for continuity where there shouldn't be any.
Sorry, I don't know how, if someone could help me out that would be great.

6)One trick is to measure across components.. you should see resistance on most, if not all.. if you see nothing - open - you have a short.
Again, can you tell me how to do this?

7)Also - check for continuity between +9 and ground in various places.. make sure you're not shorting to ground.
Super noob, I should have an outfit.  Help?

I tested all the resistors on the board and got some wierd readings on some of them and none on some.  Here is what it is supposed to be and what I got (in parentheses).  I have the multimeter set to ohms/200k mark:
R1 4.7k (0.0k)
R2 82k (80.9k)
R3 470k (No reading coming from this one)
R4 390k (191.9k)
R5 2.4k (2.4k)
R6 470k (No reading coming from this one)
R7 Trim Pot (not sure how to measure this one)
R8 470k (No reading coming from this one)
R9 220k (No reading coming from this one)
R10 10k (9.9k)
R11 1.5k (1.4k)
R12 100k (21k)
There is another hooked up to the LED 8.2k (8.0k)

No readings off the Capacitors, any of them.  I don't know how to measure the diode or the FETs, or the IC.

Looking at this I'm starting to think I had the multimeter on too low a setting to messure the 470k resistors.  This makes sense to me as all the 470k would not read.  But the 4.7k that read 0 bothers me.  Is it possible that I burned it out when soldering?

I know its a lot but any help be appreciated.  Thanks.

[smoguzbenjamin]

Use the black probe of your DMM and put this on ground. Now use the red probe to measure voltages from sepcific points. Voltages are always measured from ground.

[remow]

OK, dumb question but do I need the battery hooked up to the pedal to measure the voltage?

[bwanasonic]

OK, dumb question but do I need the battery hooked up to the pedal to measure the voltage?

Yes, and make sure you have a plug in the input jack if you use a stereo jack for switching. This one fakes me out all the time.

Kerry M

[remow]

Great, thanks for the tip.  Anyone have any ideas on the resistor values?  Or why I can't get a read on the capacitors?  Do I need the battery hooked up to read those?

Also, how do I check the FETs and Trim Pot?

[Ammscray]

Kuick kwestion: how did you hook up an LED if you used a DPDT?? That could be your problem...

[remow]

OK, here is how I have it setup:

1: Input Board
2: Ground
3: LED - (LED + to AC jack)
4: Output Volume Pot
5: Input Jack
6: Output Jack

Thanks.

[remow]

Any ideas?

[remow]

Anyone?