Guild Foxey Lady Transistors

[mcasey1]

Would the two 2N5088 transistors used in the Foxey Lady circuit need to be matched or biased in any way?  The fuzz works but it is very blatty in sound not smooth at all.

[R.G.]

Would the two 2N5088 transistors used in the Foxey Lady circuit need to be matched or biased in any way? 

No.

The fuzz works but it is very blatty in sound not smooth at all.

You have some defect. "Blatty" is almost by definition the sound of incorrect biasing.

Read "Debugging: What to do when it doesn't work" and post the info.

[mcasey1]

Guild Foxey Lady (as taken from stompbox gallery on diystompboxes.com)

Voltages:

Q1
C=0.09
B=0.62
E=0.0

Q2
C=0.22
B=0.73
E=0.13

D1
A=0.01
K=8.97

hmmmm...

[mcasey1]

The voltages seem low to me.  I wonder if the Diode is oriented correctly in the layout?

[R.G.]

It took me a while to go search out the schematic and verify the layout.

It's not working because it's severely misbiased.

Both collectors should be at about 3.5-3.7V, both emitters at about 0.16V, and both bases at about 0.7 to 0.8V.

Since the collectors are so low, it's likely that either they have the wrong collector resistor, the collectors are open, or they are getting no supply voltage. Since the emitters are at two different voltages, I'm guessing that Q1 has an open collector circuit. That's about the voltages I'd think would happen if the collector passed no current. For Q2, the right current (about...) is coming through the emitter, but the collector is too low. That's likely a wrong resistor value or a wrong connection.

Likely causes
1. soldering problems
2. wrong layout or cutting of vero strips
recheck your component placement and soldering.

[mcasey1]

Thanks.  I suppose the 2 Collector resistors are R4 and R10.  I checked these 2 and they are correct.  There are no visible errors in layout or soldering. Any more specific things I should check?

[Meanderthal]

 One thing to keep in mind is that this is one of those in-a-gadda-da-vida FZ-1 kind of fuzzes with the broken speaker sound and isn't really supposed to be all smooth. I built one, socketed the trannys, and settled on the 2N5133 buttons because they were much rougher than 5088.

You DO mean the 2 knob, not the BMP, right?

[R.G.]

Thanks.  I suppose the 2 Collector resistors are R4 and R10.  I checked these 2 and they are correct.  There are no visible errors in layout or soldering. Any more specific things I should check?

Yep. Refer to the schematic I drew up on this thing: http://www.geofex.com/FX_images/eh_axis.gif
And measure the voltage on each pin of each component, report them back here.

What's happening is that there is some connection that's not made that should be, or some connection is made that shouldn't. Since you can't find them by looking, we find them by measuring the voltages that the connections make. Those will tell us what is and is not happening; for instance, if a collector resistor is connected to +9V on one side but not to the collector, the voltage will be 9V on both ends, not 9V on one side and 3.6V on the other.

[mcasey1]

I will get to work on that very soon.  I actually own an FZ-1A, so Im familiar with nasty good and nasty bad sounds.  This is nasty as in error in circuit.

[Meanderthal]

 Just wanted to be sure... I just perfed mine right off the schematic, so I'm afraid I didn't use the layout and don't have much to say 'bout it. But, yeah, it's bad in a good way...

[mcasey1]

Just wanted to make clear up some wiring questions.  What is wrong with the way it is wired now? (I always mess up wiring).

[mcasey1]

Any pots need a ground connection here?  Probably the volume...

[Meanderthal]

 The volume pot DOES have a ground connection(red wire). The black are ground...

[9 volts]

I built the same layout. There is an error in it. C6 is 4uf (4.7uf) not 47uf as listed in the parts list.
This should put a smile on the dial!

[mcasey1]

HA! That figures.  Ill have to make a trip to Radioshack and let yall know what the results are.  Thanks.

[R.G.]

I built the same layout. There is an error in it. C6 is 4uf (4.7uf) not 47uf as listed in the parts list.

That won't affect the DC voltages at all unless the electrolytic caps are in there backwards.

And the rolloff frequency of a 680 ohm resistor with a 4.7uF cap is 49.8Hz. With a 47uF, it's 4.98Hz. Again, not something that will cause the problems being described.

The two black wires marked "Where should this go?" probably connect to the ground connections of the input and output jacks. That certainly would be a good thing to do with them.

We do still need the voltages on each component to find out exactly why the transistors are not biased properly.

[Sir H C]

I can dig mine out to see the circuit. This is the two transistor one, right?

[mcasey1]

I am not familiar at taking voltages at all the points in a circuit (not only how to do it, but how to interpret and display the results).  Are there any tutorials at this more inclusive form of measurement?  As involved as I have goten is taking voltages at ICs, diodes, and transistors, like on the DEBUG page.

[mcasey1]

The 4.7uf cap change indeed did not solve the problem.  It sounds somehwat better, but still pretty horrible.  If the clip at www.home-wrecker.com is any indication, it will be a nasty fuzz, but this is ridiculous.

[R.G.]

I am not familiar at taking voltages at all the points in a circuit (not only how to do it, but how to interpret and display the results).  Are there any tutorials at this more inclusive form of measurement?  As involved as I have goten is taking voltages at ICs, diodes, and transistors, like on the DEBUG page.

It's actually pretty simple. You hook your meter black lead to ground, and power the circuit. Then you stick the red probe onto each lead of every component, and make a list of
each component and the voltage on each of its pins. For resistors and caps, it does not matter which pin you list first, it will be obvious. For transistors and diodes, you're already doing fine.