PT2399 Dev Delay Assembly Instructions

Welcome to Synthrotek PT2399 Dev Delay Assembly Instructions! This step-by-step guide will take you through the whole circuit-building process.

Component Layout

The first step in any successful DIY electronics project is to make sure that you have all of the parts and know their reference ID for proper board placement. Check the contents of your kit against the BOM before you begin. If you’re missing anything, send us an email and we’ll get it out to you ASAP.

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Got all of your components?  It’s time to start building.


The first part of our build will be for components that are soldered directly to the circuit board.  This makes the build process easier than having to deal with wires and floating potentiometers getting in our way while we solder sensitive components.

Attention: Changes may occur after the Assembly Instructions are created and the photos may not reflect those changes. Always use the BOM to verify the placement of components.

IC Sockets/Resistors

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Insert the resistors into their respective PCB positions and solder them to the board. Use the BOM to identify resistor placement. Don’t worry too much about damaging resistors with your soldering iron; resistors are not fragile components.

Insert the IC Socket into the PCB as show above.  Make sure that you align the notch on the socket with the notch on the silk screen.  Next place the IC into the socket as well and again align the notch on the IC with the notch on the socket.  Do this carefully as to not bend the IC pins.


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There are two different types of capacitors in this circuit. Electrolytic capacitors (C2, C3, C9, C13, and C14) are polar components and their pcb placement matters. The shorter lead and the band on the body identifies the negative lead, which will be inserted into the circle through-hole. The positive lead will be longer and should be inserted into the square through-hole.

Polarity is not an issue with the remaining ceramic capacitors. Just be sure the component values are identified before soldering them; some of them look very similiar and the codes printed on their bodies are the only way to identify them.

Note: (C15, C17) could be either electrolytic or ceramic capacitors.

Voltage Regulator

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Solder the voltage regulator for U2 as shown in the picture. Align the flat side with markings on the board.

Potentiometers & Audio Jacks

Solder wired leads to a B50K potentiometer, B20K potentiometers, and both audio jacks. Connect these components to their respective locations using the photo below for reference.


1/4" Jack Wiring

1/4″ Jack Wiring

1/4" Metal Audio Jack Wiring

1/4″ Metal Audio Jack Wiring – Sleeve is Ground, Tip is IN/OUT

You may opt to mount R2/R10 directly to the PCB, but be aware that this will cause the potentiometers to increase mix/depth when turning counterclockwise.

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Some pots come with nubs near the shaft that may get in the way of installing the circuit into a case. Check for a nub and clip as necessary.

Cut the pot nubs

Don’t forget to cut the nubs on the potentiometers as necesary.

DC Jack, Power Switch, LED, and 9V Clip

 For 9V center negative wiring, connect the ‘S’ contact of the D/C jack to one of the contacts on the SPST switch – this switch will  control current flowing to both the circuit and power LED. Solder a 1K resistor to the positive (round edge) lead of the LED.  Solder two wires to the unused SPST switch contact, connecting one to the remaining contact on the 1K resistor. Solder two wires and the negative lead on the battery clip to the ‘P contact of the D/C jack, connecting one of the two wires to the negative (flat edge) lead of the LED. Connect the remaining wire running from the SPST switch to the ‘VCC’ contact on the delay, and the remaining wire from the ‘P’ contact to the ‘GND’ contact on the delay. Solder the positive battery clip lead to the ‘C’ contact on the DC jack. You may optionally omit the 9v battery clip if desired.



DC Jack Pinout

DC Jack Pinout

Warp, Feedback, and Feedblast Mods

Solder wires to both contacts on one of the momentary switches and solder a 200k resistor to one contact on the other momentary switch. Attach wires to the resistor, remaining contact on the momentary switch, and pins 2/3 on the 50k potentiometer. The momentary switch with the resistor will be used for the feedblast mod, the other momentary for the warp mod, and the 50k pot for the feedback mod.


Connect the appropriate components to the following locations:

Feedback: R10 (2) –> 50k pot (2), R11 (via adjacent C17) –> 50k pot (3)
Feedblast: Pin 8 (IC Socket) –> C3 (-)
Warp: R2 (1) –> C15 (-)

Pin 2 on the 50K feedback pot must be connected to pin 2 of R10, and the momentary switch with the 200k in-line resistor should be used for the feedblast mod. Switch polarity has no effect on the feedblast or warp mods. It may be beneficial to route wires through the holes in the corners of the board to provide strain relief for the delicate mod connections.

Completed Project



  1. hello, are there any instructions or tips for adding this at the end of an OD/fuzz circuit? thank you.

  2. Steve Harmon says:

    To chain an OD/fuzz pedal to the Dev Delay, you can wire the output tip pad of the fuzz to the input tip pad on the dev delay. Then connect the two ground/shield pads to each other.

  3. Scott says:


    I just built this as my first kit and it works great. I found the instructions easy to follow and the PCB is labelled really clearly. It was damn fun and sounds huge! One thing I did notice here in the assembly instructions is that there is no mention of inserting the IC into the socket as part of the final steps. I had to look at another assembly guide to work out how to do it (total noob here).

  4. luc says:

    Is it easy to wire in the Vac Pak to this? How would I do it?

  5. Habby9000 says:

    Hey dude, amazing work ! Im wondering, could I build one of these and mount it inside my ms20 mini ? I’ve already done some mods to the beast and I’m looking into adding a delay function. Thanks !

  6. Steve Harmon says:

    Hey, Habby9000!
    Looks like the MS-20 mini runs off a 9V DC outputting power supply, which is what the Dev Delay uses. So if you knew where to connect on the MS-20 mini and felt like drilling some holes; it seems like you’d have a rad delay mod!

  7. Philip Zerkel says:

    Kinda a noob. Just finished kit with out mods and it passes signal through it but doesnt seem to alter it at all. No delay, even with knobs turned to either extreme! Any advice on how to identify problem?

  8. Steve Harmon says:

    Hey Philip,
    I encourage you to e-mail us some board photos of the top and bottom to so I can lend another set of eyes and continue troubleshooting a bit deeper. If you have a multi-meter, you can use the continuity (beep) mode follow the different connections by following the schematic found here:
    Looking forward to your e-mail,

  9. Brian McMahon says:

    Tried powering with a 12v DC plug and the voltage regulator blew. Have the input power wired for a centre positive power supply. Is VCC supposed to be AC or DC and what are the max and min voltages?

  10. Steve Harmon says:

    Hey Brian,
    The circuit calls for a center negative DC supply with an input voltage of +6.7v-35v, as this is what the LM78l05 can actually convert to a steady +5v. Center positive supplies won’t fly with that converter, and that’s what did your build in.

  11. Brian McMahon says:

    Cool thanks man. I’ve a new one on the way anyway so I’ll re do it. I thought wiring the DC jack differently would let me use a different power supply.

  12. Steve Harmon says:

    No problem, Brian!
    We all burn and learn!
    A reason why this and many other circuits used for instruments are center negative: Because many pedals work with either a battery or a power supply; and, to preserve the life of the battery, it is disconnected from the circuit when either (1) a power plug is inserted or (2) the input plug is removed. This is accomplished by connecting the battery’s negative terminal to the input jack’s ring contact and the battery’s positive terminal to the sleeve shunt on the power jack. When the input plug is inserted, it completes the circuit for the negative battery terminal. When a power plug is inserted, it breaks the circuit to the positive terminal of the battery. Power jacks do not have a shunt for the center (pin) contact, so a center-positive power supply would not work in this type of circuit.
    Happy soldering,

  13. Jeremiah Paddock says:

    Hi! Do y’all know where I can find directions to attaching the 555 module to this?

  14. Steve Harmon says:

    Hey, Jeremiah
    It’s mentioned briefly on the 555 timer page and in passing on this video demoing it, but connecting the 555 output to Pin 6 of the PT2399 will have you jamming nicely 🙂

  15. Charles says:

    Can multiple PT2399 boards be connected in series to create ultra long delay / echo time lines?
    My guess would be this is probably possible, but wanted to get any opinions or thoughts here about this idea . . .
    many thanks

  16. Synthrotek says:

    Hi Charles, it can increase repeats, but the increase in time will still make the bit rate go down, which makes it more gritty 🙂

  17. AR/KVB says:

    I suspect this is a rudimentary (novice based) question, but… would it be possible to run both the PT2399 and the 555 from the same DC power jack? For instance, if I were planning to build them both into the same box? My thought process suggests I could simply share the current, much in the same way multiples work in a modular system. Am I off base here?

  18. Parker Medlin says:

    Hi, total noob here, wondering what changes I would need to make in order to hook this thing up to my 15v power bus that I have in my eurorack. Would I be able to get away with just using a different voltage regulator, or would this throw everything off? Sorry if this question is dumb I’m very new to electronics thanks

  19. Synthrotek says:

    Hi AR/KVB, yes certainly!

  20. Synthrotek says:

    Hi Parker, the 5V regulator that is already on the project is just fine and will work with +15

  21. Matt says:

    I have followed the instructions and triple checked my component placement for just the basic setup and I get nothing. Can you help me?

  22. Synthrotek says:

    Hi Matt check this out first:

    If you get nowhere send us an email at

  23. Kevin says:

    Is there a way to wire an on/off switch for the delay effect or is it always just on? My research only provided info on how to put a switch in the Cosmic Echo PCB. Thanks!

  24. Synthrotek says:

    Hi Kevin, the Cosmic Echo is a guitar pedal and has built in true-bypass switch. This is not the same on the Dev Delay. I am sorry!

  25. Kevin says:

    A 3pdt can’t be wired into this?

  26. Synthrotek says:

    Hi Kevin, it certainly could be, we don’t have instructions for that presently.

  27. shae says:

    In addition to Kevin’s comment… I also would like to add a 3pdt. Is there something special that would need to be done to accomplish this? I know you said you don’t have instructions currently but I guess I’m just wondering if you would just emit the SPST then wire the 3pdt like you would any other pedal.. Or if there something special you would have to do to make it work because of the type of circuit? ( I’ve only ever done OD/DIST/FUZZ’s and 1 tremolo but wired all the 3pdt the same).

  28. Synthrotek says:

    Hi Shae, you could replace the SPDT, sure, but you would also need to re-route the audio path through the 3PDT if you want to make it true bypass.

  29. Shae says:

    Gotcha so I would run a wire from c17 for effect input and another from c14 for effect out. Then BAU? Example. Pin 1 effect input pin 2 jack input pin 3 jumper to pin 9 pin 4 led pin 5 board ground pin. Nothin on pin 6, pin7 effect output pin 8 Jack output. Would that work? Thanks!

  30. Shae says:

    I have tested the method above with success ^^ only instead or running wires from C17 and C14 I just used the effect in and out on the pcb where it shows to connect the positive sides of the jacks. Then ran jack in and out to the 3PDT pins notated above.

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