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PROBLEM SOLVED!

To cut to the chase - it was the 2M2Ω resistor off of pin 12 on the TLE2074. When measuring from pin 12 of the empty socket to the 2M2Ω resistor, I got continuity. When measuring across the 2M2Ω resistor I got 2.2M Ω resistance. When measuring the from VB board input to the 2M2Ω resistor I got continuity. That is what told me the 2M2Ω resistor was good.

HOWEVER . . . ..  with the TLE2074 still out of socket, I should have been able to measure 2.2M Ω resistance from pin 12 to the VB input - but it read open. That should have been my troubleshooting "AHA!" moment. But I overlooked it because all the other readings suggested all was well.

As it turns out, the pressure of applying the DMM probes to each side of the 2M2Ω resistor was putting enough pressure to make the resistor measure properly. Without any pressure, it measured 'open'. I had reflowed that resistor twice and all the above measuring and testing remained true. So, I pulled out the 2M2Ω resistor and put in a fresh one and THEN I could read continuity from pin 12 to the VB input. I then replaced the TLE2074 chip and pins 12, 13 & 14 then gave correct voltage measurements. After which I hooked it up to my amp and guitar and VOILA! I had crystal clear chorusing with all controls doing fantastic things to the chorus settings.

Finally, I went back to the 2M2Ω resistor I had pulled and gently connected alligator clips to the leads and re-measured it. It read 'open'. I took the gator clips off and applied the DMM probes to either side and it measured 2.2M Ω. Apparently, that specific 2M2Ω resistor has an internal micro-fracture. It's in the bin and I'm happily onto finishing the enclosure for my new VFE Choral Reef pedal.

Thank you to everyone who participated.

Here are the build photos . . .







During the build process, I carefully examine the progress with a strong light and magnifying visor - double checking for any bridges and\or solder splashes. Especially before soldering the pots into place; as they cover up much of the work. I suspect there may a micro fracture (possible a scratch) through a trace near the first opamp section.

Thanks for all the suggestions thus far.

Bench update . . . .

With the TLE2074 removed:
1) pins 12 & 13 now read 4.88 volts - but pin 1 reads only 1.2v.
2) unable to measure the 2M2Ω resistor between pins #12 & #5 of the socket - but there is continuity between pin 12 and the 2M2Ω resistor; there is also continuity between pin 5 and VB - AND continuity between the other side of the 2M2Ω resistor and VB.
3) the 2M2Ω resistor measures 2.2M Ω (with the TLE2072 out of the socket.

On the SB3 board:
1) R5 & R6 are in place
2) C6 is installed reverse of the PCB markings (as per the build doc)
3) there is ~4.88 volts on the V- point and ~9v on the V+ point

Other points:
1) all 3 16mm pots have SmallBear pot condoms on them
2) with all chips in place, powered up and plugged in, all the controls have functionality. The output is just quite distorted. (The first opamp [TLE2074] section has a low-voltage condition on pins 12, 13 & 14.)
3) C18 (.22µF) is not leaky (from Mouser)
4) C12 (10µF BP) is not leaky (from Mouser)
5) Tried a few different quad opamps (TL074, TL084, OPA4134 & OPA4132) and all exhibit the same low voltage on pins 12, 13 & 14 - and all the pots still have functionality - just dirty output
6) With all chips in place and the circuit powered up, there is 4.88v at the VB points, including pin 5 of the TLE2074

I've not started pulling my hair out yet, but it's close to that pointless prospect. Clear photos coming shortly.

Any further suggestions or things to check will be appreciated.

Did you add the 2 resistors and reverse the one cap on the switching board? This is part of the "choral reef" difference on the switching board.

Yes - R5 & R6 installed and C6 installed reverse of the polarity markings on the SB3.

That'll do it, I was expecting that the BBD output op amp was going to be the problem, given how close to the rails it ends up biased.

What doesn't make sense is why all the other voltages are correct. I even swapped the TLE2074 with a fresh one - same result. (I got both TLE2074 chips from Mouser, so I should be able to assume they're both good. Or at least one of them.)

I'll look closer at the SB3 switching board to see what I can find. Without a schematic for it, I'm left to tracing from the layouts in the SB3 build doc. And I did catch the bits in that build that are exclusive to the Choral Reef.

Back to the bench . . .. .

Remember that for the Choral Reef the VB source is on the switching board. This is explained in the SB3 doc. It's the only project that requires it.

I just sorted that bit out. And I did carry over the -V line from the SB3 to the PCB. I also followed the explicit instructions in the "In the Choral Reef the following exceptions are applied" section, leaving off the charge pump IC and C5.

What sort of pickups are you using? It's not exactly designed for high headroom.

Could you please also post your MN3008 voltages regardless, just so I can double check them.

Thanks Scruffie . . . . I use a '79 Strat, so the pups are not hot. I remeasured all the voltages as shown in the chart, and the MN3008 is spot on. However, I think I've found the source of the distortion.  Pins 12, 13 & 14 of the TLE2074 are reading much lower than they ought. Instead reading 3.86, 4.88 & 4.88 respectively, they are at 0.93, 1.04 & 1.04 - also respectively to pins 12, 13 & 14 of the TLE2074. That's the first opamp section in the circuit. All other voltages are within 5% of the voltages listed in the build doc. Except pin 2 of the 4047 which measures 34mV instead of 115-118mV.

When I try to measure the 2.2MΩ resistor on pin 12 of the TLE2074 (with the TLE2074 removed) I cannot get a reading between pin 12 and the VB. Theoretically, with the TLE2074 removed, I should be able to read 2M2Ω between pins 12 and 5 on the TLE2074 socket. But it reads as 'open'.

Also, there seems to be no source of "VB" on the schematic and as such I have no reference for what VB is supposed to be. I can only guess it's supposed to be 1/2 of the supply voltage. I can easily find 4 locations on the schematic where "VB" connects to specify points, but no reference to a "VB" in the power distribution section.

Got the Choral Reef up and running today but I cannot seem to ditch the distortion. All the voltage measurements seem to match the build document voltages. And I've gone back and forth between the two trimmers to try and get rid of the distortion. No parts substitutions - except that 65K resistor where I tented two resistors that equal 65K in series.

I followed the build docs for adjusting the BBD, but it sounds very distorted. There is a sweet spot at just about midway on the BBD trimmer where the distortion is at a minimum. But I don't believe it should be that distorted.

All parts were sourced from SmallBear and Mouser.

Does anyone have any experience with the VFE Choral Reef that has a distorted output? Or are the trimpots just that fussy with only a tiny sweep section of each of the trimmers? I spent over an hour already futzing with them in very tiny increments.

TIA

Just finished wiring up a Pork Barrel 2019 and have an issue I was hoping some kind soul may have encountered and can pass along a solution. Bypass works just fine. When engaged, I have to swing the "Blend" control all the way over to get any sound. The "Rate" LED pulses and changes speed with a change in the 'Rate' control - suggesting the LFO section is working as it should. I'm using the V3102 & V3207 clock and BBD combination.

As I adjust the trimmer towards one extreme, I can begin to hear some distorted sound and modulation, but no chorus effect.

All the voltages  - EXCEPT on the V3207 BBD are correct. Here are the voltages on the V3207 BBD:
1) 0.002 (effectively zero - supposed to be Vcc [9v])
2) 4.2 (seems to be correct)
3) 3.4 (supposed to be ~4.
4) 8.1 (supposed to be ~0.61)
5) 8.8 (supposed to be ~0)
6) 0.008(effectively zero)
7) 4.65 (seems to be correct)
4.65 (seems to be correct)

I suspect a bad BBD, but would like to hear of any other insights or obvious blunders on my part.

I have NOT installed D5 (as per the build docs) and am using the vertical jumper configuration for the clock/BBD combo (also as per the build doc). All socketed devices are securely seated. All components acquired from SmallBear and\or Mouser.



Thank you for your time and consideration.

I got a few of the Softie box kits while they were available and still have one left. (The ones I built are gone and I don't recall exactly how they behaved.) The question I have is: Is it JUST a bypass switch, or can it also be quickly double-tapped to go into non-lathing mode - like a momentary stomp. And then quickly double-tapped again to go back to regular latching mode? TIA

JimiLee - so glad you finally got it working. Looks great!

Thank you. You gotta have the right 5457. It was affecting the voltage and I dont'know why. It was a bear, that's for sure.

JimiLee - FETs are a fickle device. Kinda like NOS germanium trannies in that the specs can be all over the map for any given part number. When ever applying FETs, I always socket them because it can be a crap shoot selecting them. Even with a Peak Atlas DCA75 to pre-test (measure) them, they can be fickle. Still, happy to see this done.

How do you like it? Is the swell dramatic or  . . . . . ??

JimiLee - so glad you finally got it working. Looks great!

Thank you for the photo essay. That's looks fantastic, and that soldering iron. I spent 12.00 on one just like it. It was supposed to be temporary if I liked the hobby. I used it for 8 years. It still works great, I just replaced it because I wanted a nicer one. I still use it from time to time.

Thanks JimiLee. I've had that cheap little soldering iron for 4 years now and had to replace the wand a couple month ago. It's quite inexpensive, as you've noted, and has a number of tips to change out. The replacement wand was only 4 zorkmids.

Very professional build and detailed process. The part that interested me the most is that tiny and perfectly executed LED indicator next to the Intensity control. It's so flush and unobtrusive you almost don't see it (which is the point). Well done.

Thanks!  I'll admit that I took a little extra time on the rate LED. I intentionally drilled the hole too small, then slowly with a hand-reamer kept digging at it, bit-by-bit to get it just right so just the dome was peeking thru the top. Then I used fine-mill file to flatten the LED till it sat flush in the tight hole.

Beautiful build!  Top shelf. The solder joints on the resistors are perfect.  Do you flow through the bottom just right, or touch up on the top?

Thanks! I start soldering from the bottom and touch-up on top after inspection reveals a need.