Orange Squeezer Trouble

[Paule]

Thanks for the opportunity to participate in this forum.  I could sure use the help.

This is my first build attempt.  The Orange Squeezer at http://www.tonepad.com/getFile.asp?id=88

I've made my own guitar cords for years and can solder well enough but I'm just beginning to learn about electronics at this level.  I'm learning a great deal and I'm in this for the long haul.

I got the OS working great, but then I hooked up the polarity in reverse and probably (and i could be wrong) fried something.  But what?  I'm sure the effect is powered properly now, but I only get sound when the effect is bypassed, nothing when the effect is on.  I made an Audio Probe from a plan on geofex and was able to track the signal up to the 82k resister -- one side had signal, the other not.  I replaced the resister but the same thing happened.  I've been over Aron's faq several times -- I printed them out and have made notes.  I've searched this site and have found some very useful information, but not quite what I need.

So, then I replaced the 4u7 cap near the trip pot and the first transister.  That also had no effect.  I re-soldered several connections.  Still nothing.

My meter is junk -- good for checking continuity and seeing the general effect of a pot but it doesn't give accurate readings of power or anything else.  Aron recomended the Hosfelt 9202 in his faq.  Is that what I need to make the necessary diagnostics?

Am I on the right track here?   

[Seljer]

Double check the pinouts of the transistors, go look up the datasheets on the internet.
JFETs are espescially notorious for coming in a bunch of different configurations.

[bwanasonic]

I got the OS working great, but then I hooked up the polarity in reverse and probably (and i could be wrong) fried something.  But what?

If you used tantalum caps, they are not very tolerant of polarity reversal, and at least some may have failed?

Kerry M

[Paule]

OK.  I bought a meter and checked the voltage to the opamp, as was recomended on the geofex site.  My battery reads 8.6v.  On the opamp ...

8=8.6
7=8.0
6=5.6
5=0.2
4=7.8
3=7.8
2=gr
1=gr

Is this good? 
I replaced all my 4.7mf  caps.  No change.
Once again, this thing was working fine and sounding great until I put it in it's enclosure and foolishly reversed the polarity.  (FYI; The enclosure is a hard plastic container.) 

Could the FETs be hooked up wrong and yet still work for a while at first?  I have now two PNP 1N4001 Silicon transisters that I COULD use to replace the 2N5457, but I'm a bit nervous about it.  I have Aron's FAQ's printed out and in hand and I've studied it, but transisters are still unclear to me.  When the word 'bottom' is used in reference to the FET, is that with the wires pointing toward you or away?  Also, my schematic doesn't seem to indicate where the emitter or the collector are supposed to go -- no lines.  There is what appears to be a G on one side of the drawing -- ground? base?  I just put the FET in place according to the layout given.  http://www.tonepad.com/getFile.asp?id=88

What can I do with my handy new meter to narrow my diagnosis?

[Paule]

I've downloaded the datasheets to the 2N5457s, as called for in the Orange Squeezer, and the 2N3906s I have from Radio Shack to replace them.  I put the 2N3906s in the circuit in two different ways with no result, other than making a serious mess of my perfboard.  I'm starting over on a new perfboard.

I can't tell from the datasheets if either of the transisters are PNP or NPN.  How can I find this out?  It seems to be of some importance.

Is this correct?
FET is to sourse as BJT is to emitter
FET is to drain as BJT is to collector
FET is to gate as BJT is to base

Thanks for the help.

[Toney]

That circuit had 3 X 4.7u electros to ground.

Depending on how long it "cooked" for , they may have copped it.

Apart from that, your fryables are: the diode, the Ic and Trans. Probably in that order.

First thing I'd do with that meter is check the diode, and those caps, then confirm alls honky-dory wth the trans...quick HFE test wil do.

Good luck, you'll get it going! 

[George Giblet]

Dude your pin 4 voltage should be zero volts.  That makes me think you have lost, or incorrectly connected, the ground from the PCB to the connectors, or, that pin 4 has dodgy soldering.   First check the ground track to the PCB is at 0V.

The JFETs will not do this.  The JFET line of thought doesn't make sense to me at this point.

[oldrocker]

The Orange Squeezer uses Jfets and 3906's are Bi-polar PNP's.  How do you interchange Jfets and PNP's?  They won't work in an OS as far as I know.  Go to Radio Shack and get two MPF102's.

[Toney]

Oh yes, good point. Voltage at ground!
A cooked electro can short to ground...

Deal with this first!

[oldrocker]

Quote (I have now two PNP 1N4001 Silicon transisters that I COULD use to replace the 2N5457.)
1n4001's are diodes not transistors and only have two legs so can't be bi-polar PNP's.  And the 3906 PNP's can't replace a jfet (field effect transistors).  Right?  I haven't seen anyone comment on this.

[burnt fingers]

Paule,

I think you need to slow down here.  You seem unclear as to what parts are what and what can be used as replacements.

FET's and Bipolar tranistors are not universally interchangabele even if you think you have the pinouts right.  1n4001 are silicon diodes which cannot replace either transistors or fets. 

The voltages on the IC are weird but I think we are not getting the pinout right on them.  Start with the leg nearest the dot on the IC  OR if there is no dot, the left leg of the side with the notch making sure the notch is facing upwards.  There are diagrams here to look at.  http://www.diystompboxes.com/cnews/FAQ.html   

Scott