SOLVED Parenthesis octave problem

K Pedals

K Pedals

Well-known member
I just finished the new board and everything works good except when I turn the octave on...When I engage the octave switch the more I turn the potentiometer up the less volume the distortion has... like it’s sending it to ground and there is no octave at all...
Do you see any obvious mistakes on the board/wiring???
 

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Chuck D. Bones said:
I just noticed something on the schematic. D2 and D3 are pointed the wrong way. Compare with the octave section in the War Scythe. D2 and D3 should have their cathodes connected to Q2's base, otherwise, there is no bias source for Q2. I checked the PCB photo and the board layout matches the schematic. If any of these boards work, it's because D2 and D3 are leaky enough to bias Q2 on.
Click to expand...

Will swap them around when I get home.
 
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Life.jpg


Chuck D. Bones said:
I just noticed something on the schematic. D2 and D3 are pointed the wrong way.
Click to expand...
Nope, they aren't... (debatably)

The red stripe is the Anode on these germaniums, they were pulled and tested out of circuit on two different units.

In the original the silkscreen was drawn the correct way (like a stock Ringer), but they were germaniums so they were actually installed electrically backwards (perhaps by accident?) so the PCB is laid out exactly how the original was built.

This has been confirmed in two original units.

If it's wrong, it's "wrong" just like the original was. I've flipped mine around both ways with no noticeable difference.

Would be interested to hear if this fixes yours though.
 
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Robert said:
View attachment 1364


Nope, they aren't... (debatably)

The red stripe is the Anode on these germaniums, they were pulled and tested out of circuit on two different units.

In the original the silkscreen was drawn the correct way (like a stock Ringer), but they were germaniums so they were actually installed electrically backwards (perhaps by accident?) so the PCB is laid out exactly how the original was built.

This has been confirmed in two original units.

If it's wrong, it's "wrong" just like the original was. I've flipped mine around both ways with no noticeable difference.

Would be interested to hear if this fixes yours though.
Click to expand...
Yeah those Russian diodes cause confusion...
I tried it though it didn’t fix it... still the same thing...
 
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Nostradoomus said:
Weird. Green Ringer schems usually do have the cathodes pointing to base.
Click to expand...

Yep, I triple checked this in two originals. It really messed me up the first time through. :ROFLMAO:

I've discussed this situation with a few people... My suspicion is that they were inadvertently installed the wrong way in the originals by following the silkscreen / red band on the diode, but surely the EQD guys know better than this? (Right?)

They're apparently installed this way in all of them, because you can see them facing the same way in the stock photos EQD posted.

This is one of those occasions where theory doesn't match up with reality. Is it wrong? That's not my call to make.
 
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If this is how EQD builds them (and the photo bears that out) then the circuit intentionally depends on reverse leakage in the Ge diodes. The leakage is strongly temperature dependent, so warming up the diodes with a finger could affect the octave circuit operation. Something to watch out for when testing these with the box open: clear glass diodes will act like photodiodes and conduct current if light shines on them.

Maybe someone can measure the voltage on Q2's emitter, with no guitar input to the pedal, on both a known working pedal and a "bad" pedal. If Q2 is not getting enough base current, the emitter will be near zero volts. 2N5089s have a very high HFE, so all we would need is a microamp of leakage from the diodes. Don't bother trying to measure the base voltage, the meter will load it down and give a false reading.
 
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Chuck D. Bones said:
Maybe someone can measure the voltage on Q2's emitter, with no guitar input to the pedal, on both a known working pedal and a "bad" pedal.
Click to expand...

I don't have a non working pedal here, but on my Mini (exact same circuit) the emitter is reading 3.925V.

Also, because I'm hard-headed... The base is reading 4.48V steady, doesn't seem to be loaded down at all by my meter.

Measurements are taken with all controls at noon, clipping switch in the middle.
 
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Robert said:
I don't have a non working pedal here, but on my Mini (exact same circuit) the emitter is reading 3.925V.

Also, because I'm hard-headed... The base is reading 4.48V steady, doesn't seem to be loaded down at all by my meter.

Measurements are taken with all controls at noon, clipping switch in the middle.
Click to expand...

3.925V / 10K = 392uA emitter current. The transistor is biased close to the middle of the 9V power supply and the circuit is happy. If yours is a good meter, and I expect it is, then the input impedance is 10Meg and the meter is stealing 448nA when you measure the base voltage. The crappy Harbor Freight free DMMs have only 1Meg input impedance and that would steal a much larger fraction of the diode leakage current.

Boutique pedal builders have to screen germanium transistors because their specs are all over the map. I would not surprise me one bit if they also screen germanium diodes.
 
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I notice the new "Build Docs" calls out for an ON-OFF-ON Toggle switch. The Build Docs I downloaded calls for a ON-ON-ON toggle switch and give links to where to purchase them from (which I did). Could the switch be causing all the issues?
 
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JetFixxxer said:
I notice the new "Build Docs" calls out for an ON-OFF-ON Toggle switch. The Build Docs I downloaded calls for a ON-ON-ON toggle switch and give links to where to purchase them from (which I did). Could the switch be causing all the issues?
Click to expand...
They revised the boards to take on/off/on...
But the old ones took dpdt and the new one takes spdt... but that’s still not the problem because I used the on/off/on switch on mine...
 
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JetFixxxer said:
I notice the new "Build Docs" calls out for an ON-OFF-ON Toggle switch. The Build Docs I downloaded calls for a ON-ON-ON toggle switch and give links to where to purchase them from (which I did). Could the switch be causing all the issues?
Click to expand...

The toggle switch selects between clipping diodes in the distortion section. You would still have distortion, octave, and boost even if you left the toggle switch out altogether... You just wouldn't be able to select between the three clipping options.

The switch was changed to SPDT On/Off/On because they're easier to find at almost any parts supplier and there is no confusion about "Type 1" or "Type 2".
 
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