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Hello,
Having some issues with a D’Lay build. Clean signal passes fine, both when the effect is off, and when the effect is on.
However, instead of producing the expected delay effect, there is no delay sound for 20 or 30 seconds of playing, and then scratchy lo-fi echo sounds very gradually slowly swell/build up and continue repeating indefinitely, over powering the clean signal. I don’t think this is even close to how a delay should work or sound, and isn’t musical.
I’ve checked over all component values (several times). No solder bridges, re-flowed joints, etc., and PT2399 is not malfunctioning (I’ve tried a few units that I know work, always with same result when I plug them into this build). PT2399 also appears to be getting the correct voltage.
Would appreciate any info on what might produce this strange erroneous effect? Or where might be good places to start checking voltages, etc.?
Regards,
JHello J,
Post some pictures of both sides of the board and offboard wiring so that it can be traced
Pin 1 of the PT2399 should be getting around 5v
Check the op amp voltages which should be around half the power supply 4.5v for inputs and outputs pins 1,2,3,5,6,7 with pin 4 ground and pin 8 +9v all the points on the schematic marked VR should be half power supply
I suspect your problem may lie in the buffer / mixer area IC1A and B pin voltages will tell us for sure
Expected voltages are also noted in the build document
Just in case you don’t know here’s how IC pins are laid out dot or notch indicating pin 1 then down around and up in a U shape same for any number of pins
I don’t yet have high res pics, but have taken some not quite right readings from the ICs.
With an 8.8v supply, pin three on IC1 is around 3.6 instead of 4.4, which I guess means that R9 is not within spec (however, I don’t see how this could produce the particular problem).
All the pins on IC2 look good, except for 7 and 8, which are too high. Above 3.5 instead of around 0.7 … Given that these both just go to ground via 100n caps, I’m not sure what’s gone wrong. Maybe a busted IC after all.
Once we get your images something might jump out to someone
It’s definitely a strange one which makes it interesting!
I don’t fully understand the internal workings of the PT2399 but I’d imagine with the voltages you have on pin 7 current control 1 and 8 current control 0 it’ll have some strange affect on the output
Hard to find any info but found this from Rob Strand, which is why I said check the op amp voltages thinking it could be a biasing issue
I’ve been told by the manufacturers (and there’s no other way to find this out) that pins 7 and 8 are used to smooth the a biasing supply inside the modulator (MOD) and demodulator (DEM) blocks.
the majority of the PT2399 pins ie op amp ins and outs should be vref supplied by pin 2 so half of whatever’s going into pin 1 from the regulator
I’m assuming you mean R19 with regards to IC1 easy enough to check, with no power to the circuit, remove IC1 from it’s socket and check the resitance between VR and pin 3, I’d use the junction of R17 and 18 as my VR point
Just on a whim I’d visually check your IC sockets too, I’ve had flimsy socket pins bend upwards more than once and cause weird issues
hi i’m french and i re-up this posts
I’ve got a d’lay but this pedal make some noise and i can’t use it
I’ve watching all posts about this subject but i don’t succeed
I’ve got all the good voltages in the PT2399, but in the TL072 the pin 3 is a little bit low (3.60). When i heard the pin 1 of R21 the sound is good but in the pin 1 of the TL072 a noise appears. I don’t have any sound in the pin 2 of the TL072
So if you know what can be my problem thank you very much
And I really sorry for my english 🙁
Hi Pierre,
Post some photos of your build
Both sides of the pcb and offboard wiring so that it can be traced
Post all of your IC pin voltages both the PT2399 and TL072 it’s very difficult to help without seeing your build
It would be better to start a new troubleshooting post for your build so that more people will see it
Piere – please create a new post for your troubleshooting needs. The OP of this thread may have different problems than your issues, and as such may create confusion when trying to solve two potentially different issues in one thread. Thank you for your time and consideration.
Radical CJ – with a supply level of 8.8v, it appears that a used 9v battery is being used. If that is the case, please get a fresh 9v battery and see how it behaves. A used 9v battery, even slightly, may have inadequate current to run the circuit correctly.
If you’re sure the current supply is sufficient, then I’ll wait with Billy for the photos and voltage readings.
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