Klone/Aion Refractor - IC1 pin 3 low voltage

[benf207]

Hi guys,

I built an Aion Refractor / Klone. I had an issue with the buffered bypass not working, that I eventually traced to a faulty pad/mask on the buffer output that had shorted to the adjacent ground pad, and fixed it. But in the process of troubleshooting I noticed that pin 3 on IC1 is reading at ~1V. Aion's documentation states it should be 3-4V. Does anyone know why I am measuring low? The pedal sounds as I would expect.

The only changes I made are replacing the TC1044 IC3 with an LT1054, and Z1 with 1N4744A (15V). Pins 6 and 7 on IC3 also measure differently than Aion lists, but I believe that is to be expected as it is a different chip and those outputs aren't used in the circuit.

You can see the reference voltages on pg 24 of the documentation here: https://aionelectronics.com/project/refractor-klon-centaur-ktr-kit/

Here's an image of my build: https://imgur.com/a/BQB7oAY

Thanks for the help!

[duck_arse]

hello and welcome, benf207'

measure your Vr voltage at R29//R30. measure the voltage at pin 1 IC1. are they the same, as near enough? your meter is loading the 2M of R2 and pulling the voltage when measuring, but the output pin voltage will tell you what is happening when you are not looking.

[benf207]

hello and welcome, benf207'

measure your Vr voltage at R29//R30. measure the voltage at pin 1 IC1. are they the same, as near enough? your meter is loading the 2M of R2 and pulling the voltage when measuring, but the output pin voltage will tell you what is happening when you are not looking.

Hi duck,

At R29/R30 I am measuring 4.65V, and I measure 4.70V at pin 1 IC1. 1.02V at pin3 IC1.

[antonis]

In such a case, you've a voltage drop of 3.63V across 1M bias resistor (R2)..

Check for ONLY C1/R2/pin3 proper connection..

[benf207]

Hmm, I've checked R2 is measuring correctly at 2M, C1 is a film cap with no orientation. I've looked all over and don't see anything that jumps out as wrong.

[PRR]

What is your meter? Brand, model, link to specs if handy?

However I suspect this is not a correct reading and not a problem.

[benf207]

This is the multimeter http://www.mastech-group.com/products.php?cate=93&PNo=169

I put in a fresh battery but that did not change it. You think the large resistors are just throwing off the voltage?

[benf207]

Hmm I just noticed another problem.

When I run the klone with my Keeley Katana, a high frequency tone can be heard (even when the klone is off and in true bypass mode). I tried separating the Katana from the same power supply by putting in a 9V battery and as soon as the katana is clicked on the tone can be heard.

The tone sounds like ~4095Hz.

I tried replacing the LT1054 and lifting leg 1, but that had no effect. Also replaced both op amps, no effect. 1V is still measured on pin 3 of IC1. High frequency tone still present...

[benf207]

I believe there is no issue with the pedal. I'll post what Ive learned in case anyone else runs into this.

I believe my inexpensive multimeter is not playing nice with the 2M resistors in this circuit. I was using a DMM that could only measure resistance up to 2M so the impedance of the meter was changing the circuit as I measured. I bumped up to a Klein MM400 (still an inexpensive meter by all means) but it can measure up to 40M resistors. The voltage on pin 3 now reads around 3V then slowly drops to 2.6V or so. I'm sure an even nicer meter would read more accurately.

As for the high pitch whine it seems like its just the nature of this circuit. One other person reported that it happens when engaging a different pedal https://www.thegearpage.net/board/index.php?threads/powering-a-klon-with-a-1-spot.574661/

It is strange though, as I ran my Katana on a separate 9V batt while the Klon was the only pedal on the 1spot and when the katana was engaged it made a whine. But when I reverse and run the Klon on a 9V batt and the Katana on the 1spot there's no problem.
Doesn't make sense to me but I'm going to buy an isolated PSU and call it a day.

[patrick398]

What charge pump does it use? As i recall one ones whines, the other doesn't. I think it's the MAX1044 that doesn't whine but maybe i'm wrong

[benf207]

What charge pump does it use? As i recall one ones whines, the other doesn't. I think it's the MAX1044 that doesn't whine but maybe i'm wrong

I'm using an LT1054, but I'm not sure it has anything to do with the charge pump. It happens when the Klon is off and in true bypass. As soon as I disconnect the two jumpers from the 3PDT to the main PCB the whine goes away. I guess it's some kind of ground loop problem? But I would have figured it would stop once the Katana was run on a 9V.

[MikeA]

The layout calls for a TC1044 charge pump, which wants pins 1 & 8 shorted to bump up the switching frequency outside the audio range.  Looks like those pins are shorted on the PCB for you.  The LT1054 uses pin 1 as a shutdown input when it's pulled to ground, and as a feedback input for regulation and startup, so it's not perfectly pin-compatible with the TC1044.   I've never tried running an LT1054 with +V on pin 1, so I don't know if that's contributing to your issues.  You could switch back to the TC1044, or just cut off leg 1 of an LT1054 and see if it makes a difference.

[benf207]

The layout calls for a TC1044 charge pump, which wants pins 1 & 8 shorted to bump up the switching frequency outside the audio range.  Looks like those pins are shorted on the PCB for you.  The LT1054 uses pin 1 as a shutdown input when it's pulled to ground, and as a feedback input for regulation and startup, so it's not perfectly pin-compatible with the TC1044.   I've never tried running an LT1054 with +V on pin 1, so I don't know if that's contributing to your issues.  You could switch back to the TC1044, or just cut off leg 1 of an LT1054 and see if it makes a difference.

Yeah I did try lifting leg 1 out of the socket, it did not have any impact. Perhaps I could try getting some TC1044, but I'm still not sure if that is the problem.

[benf207]

Just to close things out, I tried three different charge pumps (LT1054, TC1044SCPA, and ICL7660SCPAZ) in the Klone. Pins 1 and 8 were shorted on all chips.

LT1054 and TC1044 both produce a high pitch noise when combined with the Keeley Katana.

ICL7660 has no issues.

I reckon the problem is due to heterodyning between two charge pumps that have different clock frequencies. The Katana probably uses this same charge pump, so there is no issue.