SOLVED Parenthesis octave problem

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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Any subs used? I had that problem but had a bad 5089.
Also, what kind of amp are you plugging into? Most demoes especially for sound testing are dirty amps.
 
I subbed the IC... this is the third one I’ve build... the first 2 worked perfect... they were the old board.. I tested it on a vox mini superbeetle... but there’s definitely something wrong... when I turn the octave potentiometer all the way up it cuts the whole sound out completely... like I backward volume knob...
 
It would behoove some of us who bought boards for which there are no schematics to reverse-engineer the schematics from unpopulated boards. I came very close to doing this with the Frost Drive, but the build docs showed up before I was ready to start assembly. I understand if PedalPCB is bound by agreement to not release certain schematics, but we are under no such obligation.

Oh, and nice 'scope. The CRT display is very retro. My Tek 465 is in need of some TLC and I have since migrated to a USB scope. But I do miss turning the knobs.
 
Oh, and nice 'scope. The CRT display is very retro. My Tek 465 is in need of some TLC and I have since migrated to a USB scope. But I do miss turning the knobs.

Thanks! I have another scope on top of that one :). I want a digital one but can't justify it as I know very little about using this one. I actually have a USB Hantek, not too keen on the software that came with it. I tried some open software as well.
 
PF5102 (Q1) I'm getting voltage when I put my POS of my DMM onto Source and NEG on Drain.. using this data sheet http://rtellason.com/transdat/pf5102.pdf for pinout. I'm assuming I'm getting residue voltage from the circuit and that's why I get the reading. Q3, Q4, and Q2 all check normal.

Also for the OCT SW I'm getting continuity between 1, 2, 3 and it doesn't matter if the switch is engaged or not.
 
Haven't found a smoking gun. I've been through that whole circuit.

Put a sound probe on OCT Switch with it engaged
Terminal 1 D6 changes brightness with pot moved towards the full position
Terminal 2 D6 stays the same, moving pot to full open and full closed gets louder right before you reach the end of travel in both direction. Between that the sound is lower than what I'm getting from Terminal 1 and even lower than full open and full closed.
Terminal 3 Same as Terminal 2
Terminal 7 = no sound
Terminal 8 as loud as if in bypass
Terminal 9 same as Terminal 8

 
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Here's some audio I recorded..
Clean
Engaged w/ clipping switch started off at the bottom, moved to middle (22 second), and then top (41 second).
Engaged with Octave engaged and knob at 12.. (59 second), Then I turn the knob all the way to full, it starts to fade until no sound is heard. At 1:07 I turn the knob quickly to full a few times. The remainder the knob is at 12 and I go through all the switch positions.
 
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.
 
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