Roland AP-7 Jet Phaser - let's get it working! (Aion FX Octatron)

The 2SK30A-GR seem to have the pinout Source, Drain, Gate, versus the J201, 2n5457 pinout which is Drain, Source, Gate.

Are the source and drain interchangeable here or will I need to use a differnet so-23 to to-92 adaptor for this?
 
neiltheseal said:
The 2SK30A-GR seem to have the pinout Source, Drain, Gate, versus the J201, 2n5457 pinout which is Drain, Source, Gate.

Are the source and drain interchangeable here or will I need to use a differnet so-23 to to-92 adaptor for this?
Click to expand...
All JFETs exhibit interchangeable source & gate pins. It the nature of their design.
 
Cybercow said:
All JFETs exhibit interchangeable source & gate pins. It the nature of their design.
Click to expand...

Correct - in this case Toshiba just arbitrarily labeled them differently than the standard, but in construction they're identical to the J201, 2N5457, etc.

...At this point someone will usually chime in and point out that this is only true most of the time, that there are technically some JFETs where the source & drain are not interchangeable. I've never encountered one in our corner of the electronics ecosystem. It probably goes back to the early days of JFETs, a conventional wisdom that was passed down from the elders because it was true at one time, but it's no longer relevant to what we do.

In any case, I've tested the Toshibas and verified that source & drain are interchangeable even though the datasheet doesn't say it.
 
I spent a lot more time than I'd like to admit troubleshooting a SMD footprint where my component tester was showing the source & drain as being swapped..
 
For those of you who are interested here is the tayda template for this project. Per my norm I used 3mm leds with no bezel and the smaller lumberg style power jack so adjust to taste. This is based on the most recent template so this should be correct but of course its not verified yet.

Tayda Electronics Drill

Tayda Electronics Drill Designer for custom enclosures.
drill.taydakits.com drill.taydakits.com
 
I recently got a package in the mail from Kevin. I'm going through the build doc and looking at my parts on hand and will likely be making an order to SBP for this. Having built the antipode and not seeing a need for that part of the circuit I'm thinking of hardwiring the switch for the distortion off and only focusing on the phaser side of this. @aion do you see any reason that would be an issue?
 
Guardians of the analog said:
I recently got a package in the mail from Kevin. I'm going through the build doc and looking at my parts on hand and will likely be making an order to SBP for this. Having built the antipode and not seeing a need for that part of the circuit I'm thinking of hardwiring the switch for the distortion off and only focusing on the phaser side of this. @aion do you see any reason that would be an issue?
Click to expand...
Should be fine - the distortion section is true-bypassed when off and the phaser issue does happen either way.

That said, the distortion section is all very cheap parts and it seems like it would be more work to bypass it and figure out what to do with that half of the enclosure, and how to mount the footswitch board with only one switch... so if it was me I would do the whole thing just to avoid the hassle.
 
aion said:
Should be fine - the distortion section is true-bypassed when off and the phaser issue does happen either way.

That said, the distortion section is all very cheap parts and it seems like it would be more work to bypass it and figure out what to do with that half of the enclosure, and how to mount the footswitch board with only one switch... so if it was me I would do the whole thing just to avoid the hassle.
Click to expand...
Technically I'd still have 2 switches on the footswitch board 😂 I'm not planning on boxing it up unless I can get it working properly. Im just trying to help see what going on. I have time to figure out if I'm gonna box it up and go from there.

On a side note, I see that half the lm358 is used in the phaser as well. Have you tried any other opamps? That's not part of the LFO is it? If not I doubt that's the issue. Just an observation
 
Just got mine too: I’ll be building it stock to start to try to capture the “ghost in the machine” that Kevin is trying to bust, but I’m a fan of symmetrical knob layouts, so I’ll be adding an AMZ presence control to the tone stack after the fact.
 
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