Aion fx Refractor, IC3 Pins 6 and 7 off

[MDL]

Hi guys,

Just finished my first pedal, an aion fx refractor. I really liked the process and aion's great documentation definitely helped with making my first build.
It seems to be working but gets noisy when cranked up (i understand that this is expected, and i have no comparison to judge if that noise is excessive.

Here are my measured voltages:

Ic1
1  4.58
2  4.58
3  1.03
4  0
5  4.51
6  4.58
7  4.58
8  9.18

Ic2
1  4.55
2  4.58
3  4.53
4  -8.84
5  4.53
6  4.58
7  4.62
8  16.68

Ic3
1  9.18
2  4.68
3  0
4  -4.29
5  -8.85
6  2.55
7  1.44
8  9.18

So everything more or less tracks with the voltages posted in the
documentation
except ic1 pin 3 and ic3 pins 6 and 7.
Not sure what to make of ic1 pin3, but i'm a bit confused about ic3. All the other other pins on ic3 are in the right range, and the two that are off are not connected to anything according to the schematic.
Does this mean ic3 is faulty?
Is this something i should keep troubleshooting as it could lead to issues later on?
Could this be related to higher than normal noise?

Best,

[duck_arse]

MDL, welcome to the forum. we should start a club for the first builders of the Refractor.

opamps. see the output of that oppie is connected back to the input. the ouput follows whatever voltage is at its other input - so if the output volts is good, the input volts must also be good. you can prove this by reading the out volts at the same time as you read the in volts, and they'll both show 1V03.

and that's because your meter is across that 2M resistor and ground, so you've loaded the bias string, pulled the V/2 way down. if you measure between V+ and pin 3, what do you get?

and as for pins not connected to the circuit, let them be. they don't know, we don't know. you can't troubleshoot what isn't documented.

descibe the noise and how it troubles you, others might have insights on that.

[PRR]

Welcome.

> except ic1 pin 3
 
What kind of meter do you use, brand and model #? Cuz the reading on pin3 suggests a 580k loading, which is lower than we like to use, but reasonable if you keep it in mind. And as Stephen says: pins 1 & 2 are buffered copies of pin 3, and do read right, so the circuit is fine until you poke pin 3.

[MDL]

Thanks for the replies.
I'm away over the weekend but will check v+ and pin 3 when I get back. The meter I used was a Kobalt mini multimeter, I guess that's likely not the best tool for the job...

[PRR]

Kobalt mini multimeter

Is that the Kobalt Digital Display Multimeter Item #2545069 ?

https://www.lowes.com/pd/Kobalt-Digital-Multimeter-0-2-Amp-500V-Volt/5001927061
Manual: http://pdf.lowes.com/productdocuments/e75f9370-ec17-448f-90ac-09caaabcc556/45985030.pdf

$22 at Lowes, $25 used on eBay(??)

Like most meters today, it is fine for light gentle use. Schoolkids will break the leads, etc.

IF that IS your meter, the input loading is Approx 1Meg. "Better" tech use a 11Meg meter which is nearly no loading on practical circuits. 1Meg loading will throw-off bias readings around 1Meg resistors, of course. That partly explains your one weird pin voltage, but not quite.

I would not rush to replace that meter. It's fine. It will get goofy (read high) when the battery runs down (don't rely on a LO BATT display). Some day it will read erratically or not at all, depending how you hold the probe or lead. Repairing cheap leads is a time sink; if you use it that much, get a better meter.

[duck_arse]

your Lowes won't even let me see their site. our Lowes - different story. warning - ex-footballers as comics.

[PRR]

your Lowes won't even let me see their site.

I did not know that. "My" Lowes is a home and carpenter supply warehouse. What's yours, Bunnings? I see they have meters just like this one but different color and range. But I recognized "Kobalt" as the house-brand for Lowes' tools. Oh, Bunnings doubted I was a human.

our Lowes - different story. warning - ex-footballers as comics.

I see.

[MDL]

Kobalt mini multimeter

Is that the Kobalt Digital Display Multimeter Item #2545069 ?

https://www.lowes.com/pd/Kobalt-Digital-Multimeter-0-2-Amp-500V-Volt/5001927061
Manual: http://pdf.lowes.com/productdocuments/e75f9370-ec17-448f-90ac-09caaabcc556/45985030.pdf

Sorry, took me a while to get back here. Yes, that is it.
I checked between V+ and pin3 and that also shows around 1V, so that must be the meter loading giving me that lower reading with respect to ground / higher reading with respect to V+.
Thanks for the explanations.

As for the noise, I actually think that it's pretty reasonable. The only thing that was weird is that with gain and output on max a get a high pitched squeal when setting the treble knob past 2 o'clock. Sounds kinda like feedback. But then again that is far off from a reasonable setting.