AionFX Elysium Troubleshooting/Debugging.

[valveandsound]

Hello everyone, I have been building pedals of all stripes for several years but this one has me really stumped.

Project is the Elysium from AionFX. This is an Ibanez Echomachine EM5 clone.


I assembled the Elysium PCB kit with the supplied components, performed the delay range calibration and confirmed wiring was correct. However I get very weak repeats with no sustain.

Steps I confirmed in building the unit:
1. Verified all resistors were correct value for given location
2. Verified the unit does pass audio cleanly in the dry path and at unity gain from input signal
3. Reflowed all solder joints, checking for solder bridges
4. Verified voltages should be at locations as noted in schematic.

Next thing I did was run a 1Khz tone at 128mvAC into the input.

On Pin 22 of the M65831AP I get around 220-230mvAC signal.

On Pin 15 I get approximately 20mV of signal from what I believe is the chip output.
At the output of the following opamp stage pin 1 i get 38mVAC.

Steps I confirmed after this:

5. Double checked and confirmed all resistor values in this region of the circuit.
6. Ordered another M65831AP chip from AionFX
7. Swapped around the LM833Ns from IC1 to IC2
8. Confirmed oscillator works from roughly 600khz to 4Mhz, which is in spec as per the documentation.
9. Confirmed voltages were correct on M65831AP (confirmed VC on all the required pins listed on the schematic)
10. Lifted R21 from circuit to ensure that nothing downstream was loading the output down.

After the above steps I still get no improvement in the signal. I am at my absolute wits end with this thing.

So, a small request to anyone who might have a completed version of this proejct? if I can make of you? Could you please confirm what kind of output signal I should expect from the M65831AP chip itself for a given input voltage, and what level should I expect from the output of IC2A? I suppose it's possible that I received 2 bad M65831AP chips but this seems incredibly unlikely to me.

Can confirm the dry signal works properly, and the delay range, even when heard faintly, correlates with proper delay times. So the only thing I can conclude is something is amiss with the output of the M65831AP chip.

Any thoughts or comments would be of great help.

I have included an annotated schematic to show where voltages were shown, it is attached.

Below is a link to the documentation from AionFX:

[valveandsound]

https://aionfx.com/app/files/docs/elysium_documentation.pdf

[valveandsound]

[aion]

I can confirm we've never had any individual reports of the delay chip failing, so I would focus elsewhere, mainly the oscillator (everything to the right of the chip in the schematic) which is directly responsible for controlling the chip. If something is wrong with the oscillator, then it will seem like the chip is bad because it's not performing correctly, but the oscillator is the puppetmaster so to speak.

You could also look more at the feedback path, but a signal boost is to be expected from the IC2A stage so I don't think it's that.

[valveandsound]

Thanks for the follow up. These are scope shots from the Xtal pin on the delay chip. Seems like these should look cleaner. Does the oscillator produce a pretty clean sine wave?

[valveandsound]

Thanks for the follow up. These are scope shots from the Xtal pin on the delay chip. Seems like these should look cleaner. Does the oscillator produce a pretty clean sine wave?

[valveandsound]

I went ahead and replaced everything in the oscillator circuit except for resistors, which measured correct. This is what the clock signal looks like now, and at Pin 2 of the IC. Should it have this much ring on the edge?

[valveandsound]

scope shots are here:

https://imgur.com/a/xM8779d

https://imgur.com/a/dlQIxln

[amptramp]

scope shots are here:

https://imgur.com/a/xM8779d

https://imgur.com/a/dlQIxln


It is difficult to avoid overshoots and ringing on a square wave.  If you are fixated on getting rid of it, you could use a pair of diodes biased to conduct when the wave exceeds the normal high and low levels but I doubt the ringing will actually do anything detrimental.

[ElectricDruid]

scope shots are here:

https://imgur.com/a/xM8779d

https://imgur.com/a/dlQIxln

It is difficult to avoid overshoots and ringing on a square wave.  If you are fixated on getting rid of it, you could use a pair of diodes biased to conduct when the wave exceeds the normal high and low levels but I doubt the ringing will actually do anything detrimental.

+1 agree.For a roughly-5MHz waveform, that looks alright to me.

[valveandsound]

Thanks everyone for chiming in. If incoming clock seems clean enough I guess I will move on to looking somewhere else!