Orange Squeezer yet again

[Krinor]

Hi guys.

This is my first post on this forum, and unfortunately it is not a happy one.

I built the OSQ kit from GGG and like someone else on this forum I managed to break the 1N100 diode. Seems like JD has made the holes on the PCB too close to each other and if you press the diode down to make it fit in nicely, it breaks. Anyway - JD sent me another diode free of charge. Great guy. I soldered in this one and the compressor worked fine. I fiddled around with the trimpot to make the effect sound good and then played for a while before putting on the back plate. After that the trouble started.

There was a noticeable increasing hiss on sustained notes which grew very loud. White noise. Then after a few days it almost seemed like the trimpot adjustment didn't suit the JFETs or something. Ripple and scratching and hissing all the way. A totaly useless effect and one that I could never have used at a gig or in the studio for that matter.

Tonight I opened the thing and sat down to figure it out. All voltage readings were acceptable and I checked every joint for faults. Everything is fine, like my other effects. I have never had any trouble. But after doing the voltage readings the effect suddenly didn't work at all anymore.

What might be wrong? Is it possible to destroy a component while meassuring the voltages or something ?

Now after the thing stopped working I have re-checked every joint and I get no readings at C7, R12, 1N100 and 1k5.

What should I look for ? Do I have to desolder the whole thing and start over ?

Anyone ?

[Mark Hammer]

Hiss between notes is a very common occurence in compressors.  Common enough that the SSM compressor chip also includes a built-in downward-expander/noise-gate function.  Hiss during notes, however, is not a common occurrence and suggests something particularly wrong.  Whatever is wrong is certainly not going to be damage via testing/measuring the components, though.  I can't think of anything that you might damage by touching a probe where it ought not to be.

You note that the hissing started after you set the trimpot and installed the board inside the chassis.  The cover isn't somehow touching/shorting something, is it?

Also, you didn't happen to power it with an externa supply that might have been misconnected?

[Krinor]

Hiss between notes is a very common occurence in compressors. 

You note that the hissing started after you set the trimpot and installed the board inside the chassis.  The cover isn't somehow touching/shorting something, is it?

Also, you didn't happen to power it with an externa supply that might have been misconnected?

Thanks for the reply.

Yes that's right the hissing was between the notes. Okay so this is normal ? I have never used compressors before and so far I find it frustrating. 

The board was touching one of the walls of the box. But only the side of the PCB. That shouldn't make any hiss ? The ring of the stereo jack might have touched the back plate though. There's a ground wire on that one. I have only used a brand new Duracell battery with the unit. It seems like the problem is somewhere inside the components. It's not working at all now. All wires are soldered neatly and there is no sign of breaks anywehere. The only thing that works is the signal bypass.

[Krinor]

Okay, let's put it another way:

Which parts might fail in  this circuit, and how ?
Might I have cooked a capacitor, roasted the intestines of an op amp or squeezed the juice out of a trimpot ?
I am bewildered. 

[the recluse]

I have successfully built this kit and noticed a similar issue.  I have read elsewhere on this forum that the ripple can be exaggerated by noise or an unfiltered powersupply.  While I do notice the ripple when running off of a battery, it seems to go away/lessen when I use my power supply.  Before you do anything else, try to get it back up and running, and then try using it with a decent external power supply.  I believe the more you turn up the trim pot the more prevalent the ripple will be as well.  I think one thing to keep in mind with this compressor (and from what I understand, the Ross/Dyna as well) is that it is not supposed to be transparent and hi-fi like a studio compressor, rather the coloration it does add to the sound is what it is sought after.  Good Luck!

[R.G.]

Let's ask the obvious - does taking the back plate back off make it sound good again?

Compressors hiss because they work by turning up the gain to try to make the output signal level constant. If there is no guitar signal to boost, they try to bring any noise up to the right level. However, it seems that when you put it in the box you caused some extra level of hiss that is now being amplified.

There is no way to tell what happened from your description. If in fact putting the back plate on is what caused this, then it may have cracked a solder joint, broken a resistor, made the trimpot loose, any one of a number of things.

If it were mine, I would first remelt all the solder joints with a touch of fresh rosin core solder. Don't cook them, just remelt them to be smooth and shiny. If that didn't do it, I would use 5x or 10x magnification and look for mechanical damage.

[Mark Hammer]

Ditto.

Compressors are one of the most widely misunderstood effects pedals, and many of the things that some novices report as "problems" are simply a compressor doing what it was meant to do.  A bit like people wondering if there is something wrong with their baby because it pees and poops a lot, spits up food, can't stand upright, and never sleeps for more than an hour or two at a time.

It probably doesn't help that too many compressors are sold as "sustainers".  That tends to set up unreasonable expectations about what they can and can't do, and distracts away from their inherent design weaknesses.

Incidentally, you will note that the SSM2166 compressor chip also includes on-board noise reduction circuitry - a testament to how much one ought to expect objectionable hiss in a compressor, even when it is a well-designed one.

[Krinor]

Now this is realy freaky!

Yesterday I put this faulty OSQ on a shelf and thought "oh well" *sigh*

But when I got home from work today, bringing a brand new DMM, I did a thorough testing of the whole thing.
Nothing wrong anywhere that I can measure or see (under a very sharp light). Then I thought to myself "hm... I wonder if...", and then I plugged it in between my guitar and my champ amp - and lo and behold! The little bastard was working. I swear I haven't touched it with anything but the needles of my DMM and now it works.

The hiss is gone. It compresses the signal a wee little bit. Not much, but its working. There is a sort of tremolo like effect, very weak, instead of the obscene amplification it had before it broke down. The notes doesn't sustain much. Just a little bit.

I had decided to hate this little fella. Now I love it! This compressor is mindboggling. 

Yes Mark, it's very much like a little baby.
The big question now is: Is there life in there ?   

Thank you all for your elaborate answers. For now I think I will leave my little OSQ baby alone... Unless you have some tips on how to make it poop a bit more ?

Very, very strange effect. I suspect I shall build more compressors. Many more.