Aion Vector Delay no sound when switched on

[antonis]

I'm not sure where to start troubleshooting, like what points to check voltage,  and what voltages should be correct?

First of all, build documentation..
https://aionfx.com/app/files/docs/vector_kit_documentation.pdf

Next..

[Muttlyboy]

Hi Everybody,
This is my 3rd project. The 1st two (both are Aion overdrives) went super smooth.

This delay pedal is a bit more involved and it looks like this will be my first attempt at Troubleshooting.

I didn't know where to start so I did the easy stuff first.

Battery is new and reads 9.6v by itself.
Battery clip connected also reads 9.6v.
With a plug in the input jack, battery pulls down to 9.2v. I wonder if that might indicate a short somewhere in the circuit.

Next easy thing was to check for a resistance from + to -.

With no plug in the input jack, the meter reads open. With the plug in the input jack, it reads 17k ohms.

I don't know what would be considered normal voltage drop at the battery when in circuit. Is 0.4v pulled down Normal?

Thanks

[Muttlyboy]

I forgot to mention that the pedal will pass guitar signal through when in bypass,  but there is no sound when switched on. The indicator LED light works when switched on.

[Ripthorn]

Here's a good basic debugging guide.

[Muttlyboy]

Thanks for that voltage chart...

Already there's a problem at the first point my voltage at "va" reads 8.3V. Battery reads 9.6.

I started another post as suggested, Thanks again!

[antonis]

Already there's a problem at the first point my voltage at "va" reads 8.3V. Battery reads 9.6.

What are the readings at VB and VC..??

[duck_arse]

order of posts went funny in merge. title too. please pardon. carry on.

[Muttlyboy]

VB reads 0.67 V at the filter cap, and at pin3 on IC1.

I checked the voltage at R18 an R19. The input side of R18 reads 8.25V, and it reads that super low 0.67V at the junction of R18 and R19.

The resistors are pre labeled with the values. R18 reads 10k as marked with the meter in circuit. R19 reads 820 ohms, but marked as 10k.

I don't know if the reading is bad due to a mislabeled resistors, or if just a funny reading because it's in circuit

[Muttlyboy]

So, I thought I was smart for a minute...
Nope. I clipped that resistor out and it read just right at 10k.

I have some half watt resistors,  so I'll see if I can fit one back in

[Muttlyboy]

More information...
"VC" checks as 5.06V.
The regulator is 8.2V at pin3 and 5.06V at pin1.

The IC1 readings look very wrong with the only things looking "normal" being pin 4 ground continuity,  and pin8 showing the V"a" voltage of 8.28V.

All other pins were well under 1 volt.

I removed IC1 from the socket and checked voltage again.

With IC1 removed V"B" jumped to 4.07V.

Pin1 0.01V
Pin2 0.01V
Pin3 4.07V
Pin4 Ground
Pin5 4.06V
Pin6 0.03V
Pin7 0.03V
Pin8 8.26V

[idy]

So about this r19 business:
the junction of r18/r19 is supposed to give you half your supply voltage to bias everything up.
measuring ohms I curcuit is sometimes misleading. Since r19 is in parallel with a big cap (c21) I would expect you to first read something small (like 820ohms, about 1k) and then see, as the cap begins to charge up from your meter, as that value floats up to the proper 10k.

You maybe know: ohms can only be measured with no power to the circuit?(!)

If you are getting a normal supply voltage, close to 9v, and you are not getting close to half of that (nominally 4.5v) at the junction, it suggests a path to ground from that "node." That node is called VB on there schematic.

There are only two places that VB goes to: pins 3 and 5 on the opamp, IC1. I would look with a lens and make sure there is no short anywhere near there.

The voltage drop you reported initially between unloaded battery and circuit power up sounds about right. It was still over 9v. But reading 8.2 after the zener diode and 33ohm R, "VA" seems a little low. But not enough off the stop things from working.

If you only have 8.2V at VA, then the readings you see with the IC removed would be correct: Supply on 8, ground on 1, and pins 3 and 5 get 1/2 the supply, just over 4v.

Making sure you are putting the IC in correctly, does it bias up now? (that means that all the non-supply pins read around 4v. You may notice 3 and 5 read a bit low, that's you meter "loading" these delicate inputs.)

If no, do you have another dual opamp? Any kind will do to try out.

[Muttlyboy]

Okay...I think I'm the victim of a faulty Op-Amp.

I had just put together a couple different overdrive pedals by Aion, and they all have sockets for the Op-Amp chip.

The chip for the Vector delay is a TL071. I substituted the JRC 4580D chip from my Achilles Overdrive, and the voltages started to look more like the voltages listed on the Schematic posted above. I reassembled the parts in the enclosure and...

It WORKS!

[Muttlyboy]

Thanks very much, Guys...
And Thank You Antonis for posting that Voltage chart

[Muttlyboy]

By the way,  What Op-Amp Chip should I put in a Delay pedal?
Would that fancy Burr Brown chip be noticeable in a delay pedal?

Thanks again

[PRR]

> TL071. I substituted the JRC 4580D

One is a Single opamp. The other is a Dual opamp. One of them was wrong.

[Muttlyboy]

On the list of parts from the Aion website,  they list the Opamp as a TL072...

I had to get the right light and angle to get a readable picture on my phone, and saw that it was a TL071

[idy]

That would explain everything. Single opamp. Won't work! even the power pins are different. Get a dual and cross your fingers...

[Muttlyboy]

Yeah, I swapped in the chip from my Achilles kit, and the Delay works.

In the notes on the Aion website they say a good opamp for the Vector would be an 0PA2134, but I guess the stock chip is the TL072.
Looks like the OPA2134 is hard to find from a safe source.

[duck_arse]

I had to get the right light and angle to get a readable picture on my phone, and saw that it was a TL071

wait a minute - you have photos, but you haven't posted them for us to see? remember I said we'd be wanting pics of completed builds? well, we need pics of faulty builds, it's the law.

[Muttlyboy]

I'm having trouble trying to post a picture