Sproing Deluxe - no Tremolo

[rhinoburger]

Hi all.

I ordered and built a Sproing Deluxe PCB - after emailing to ask for a bill of materials and being advised that all values were printed on the board. Great!

I built it up, and the reverb side of the pedal does work - but only one knob, the "Reverb" knob by looking at the faceplate. The "Shape" knob MAY do something, but if it does it is pretty subtle. I'm not convinced I hear a difference between fully down and fully up, but there may be more modulation in the reverb all the way up. The reverb sounds great, I'm really excited about that part

The trem side does not work at all, and when activated, it cuts the signal entirely. The LED hooked to the light sensitive resistor does not turn on or flash (I used a white clear LED and a GL5528 resistor). None of the trem knobs (Intensity, Gain, Speed) make any sort of sound when swept.

Bypass does work. Weirdly, neither status LED turns on when the stomp switch is engaged. I did check for polarity (A = Anode = Positive = long leg) and I tested the LEDs separately to ensure they function individually as components.

Voltages below, using suggested TL072 for IC1, 3, 4 and JRC4558 for IC2 :

1:
4.59
4.59
4.21
0.2
4.58
4.58
4.59
9.14

2:
4.4
4.44
4.3
0.2
4.4
4.4
4.4
8.61

3:
4.57
4.58
4.58
0.5
4.58
4.58
4.58
9.14

4:
4.58
4.58
4.56
0
4.78 (reducing)
4.57
4.58
9.15

 

[Guardians of the analog]

First we need clear pictures of both sides of the board and all wiring. All knobs except for reverb are part of the tremolo section.

 

[rhinoburger]

Photos found here.

 

[swelchy]

Your build looks soldered pretty decent... My bet is on the footswitch breakout board... you have a lot of solder there and may have flowed so much it's connecting to other pins.... I've learned not fill the holes completely

 

[rhinoburger]

No dice on that I checked everything for continuity, no shorts.

 

[Feral Feline]

For either status LED, you tested the components and ensured you knew which leg was anode/cathode, but a lot of people get the pads for the LEDs mixed up and stick the wrong leg in the square-pad's hole. If you look at your LEDs closely, you'll see a slightly flat spot nearest the cathode leg of the LED; based on the pics, you've got your anodes' legs in the kathode-holes of the PCB.





Given that you've got nada-zip-zero signal on the tremolo side, but have tested the switch for shorts, now move up the chain. Is there a short in the daughterboard's connections to the main PCB? Are there shorts at the Main PCB where the daughterboard hooks in? The tremolo circuit, if I recall is basically the MOONSHOT, for which there is a schematic, so check the schematic of that and compare to your SPROING DLX PCB even though the refdes will be different. Following the signal path through, is the input capacitor C7 suspect or passing signal? (Sproing's C7 = C1 on the Moonshot).

Next in line is R16, the second resistor above C7, have you got signal on both sides of that? Based on the above pic of the PCB, R16 hooks into pin 2 of the op-amp IC4, just like the Moonshot so check Pin-1 to see if you've got signal coming out and getting to LDR-1, the signal's next point of reference... hopefully you've found the trouble by now, but if not, keep going til you find where the signal stops.

Check R24, it's got a weird yellow hue to one side of it and I don't know where it belongs in the grand schematic of things 'cause the PCB-Pics don't show clearly where the tracing goes.

 

[Bricksnbeatles]

I’d guess the LEDs are backwards. If your status LEDs are backwards, that would suggest that the led for your LDR is also backwards, and if that keeps it from lighting up, it would explain the issue— your LDR would always be at it’s maximum dark resistance

 

[Feral Feline]

Good call, Nick, I should've extrapolated that after seeing the status-LEDs were backwards, but... I'm crap at diagnosing/troubleshooting.

 

[rhinoburger]

Yes, the three LEDs were backwards. Somehow I had all three backward, despite triple checking the meaning of the square pad vs round pad, A vs K, and still writing it out correctly on the initial post.

Good news is, I got everything switched around and the effect works. Thanks all!