Phase II - High pitched noise that follows LFO of the LED

[Bonnefooi]

Hello all, just finished my first build of the Phase II kit, what a lovely unit this is...
However i'm running into a issue with the build, im afrain i might messed something up although i took my time and did a pretty OK job on the soldering and placing component i hope.

The effect is working, but with the effect on there is a high pitch present on the background that following the LED when it changes when i turn the pots, when i adjust the trimpots and the LED turns off for a longer moment the high pitched ring fades away and when the led goes on, its back again, the brigther the LED shines (when adjusting the trimpot) the higher/louder the pitched noise gets.
I moved the wires away from the LED and took the PCB out of the case, no difference at all.., Could it be a faulty component or a soldering error?

- I swiched out all TL072 (i have a duo phase kit i want to build next..)
- reflowed soldering points

The problem is still present and to be honest i have no idea where to look or what could be the issue!

I would be grateful of one of you experiences builders could point me into some directions, i might have overlooked something simple as i'm not very experienced with building these kind of pedals! Thanks for your time.

I've added a video where you can hear the issue:

 

[Chuck D. Bones]

We can't read any of the stand-up resistors. Have you rechecked that all of them are the right value and none of the leads are touching anything?

In the video, what is plugged into the Phase II input?

Is the cover on for any part of the video? Does putting the cover on change the sound?

If you turn FDBK all the way down, does it make the squeal diminish?

Keep the wires far away from IC7.

 

[Bonnefooi]

Rechecking all the resistor values tonight. It was a supplied kit with all the correct values labeled though.

Checking the leads again... see if i missed anything.

Cover on changes the sound a little bit but not Feedback has little effect...

I have a rhodes plugged in, the squeelching is there also when nothing is plugged it. In bypass its dead quiet.

 

[Chuck D. Bones]

What are you using to power it? Have you tried a battery?

It's possible to have all the right parts, but not get all of them in the right place.

Have you cleaned the board?

 

[Bonnefooi]

I am using a universal power supply that also powers my moogerfooger pedal (i can take out the tip and turn it around to change polarity) , will check battery tonight!!

I havent cleaned the board... will do so, i have 99% iso alcohol

What i did notice as well... when the input and output cables where unplugged and the pedal was powered on and i touched some jacks i could hear some grounding, high pitched noise coming from my speakers when i was fiddeling with the pedal. I have a old house with non grounded power sockets...

The moogerfooger pedal works fine though..

Thanks for taking the time to help me out here!!!

 

[GenoBluzGtr]

There are no dust covers on those pots, are you sure....
1. There is not contact on the back of the Circuit board with the metal pot bodies?
2. That "IN" jack doesn't spring down when a jack is plugged in and touch the metal pot body underneath it? - EDIT:
Nevermind this one, after watching your video, I see that the noise is there without the jacks out of the enclosure.

 

[Nostradoomus]

Shorten your wiring up, especially to your in/out jacks. I’ve built a few phasor ii boards and placement of jacks and wires around the LFO is critical.

 

[Bonnefooi]

Hey all,

Reporting back after a evening trying to solve the problem:

- Cleaned the PCB
- Shortend the wiring
- Added a rubber pad below the feedback pot to insure the body is not touching the pcb when mounted
- Checked all components for correct value (they all seem to be correctly placed, unless i made a error with this)
- reflowed some solder pads after cleaning the pcb

The problem was still there when using a power supply (its a generic switchable voltage power supply, kinda cheap universal one)

Connected a battery to the input and the loud squeelching is gone!!
Now its just a tiny tiny bit present in the back ground when feedback turned up, which seems normal for a analog effect like this.

Could someone explain or point me into the direction to find out why the unit behaves like this with a battery?
Should i use a different power adapter or maybe the old electrical system in my house is the issue with this pedal?

Thanks again for your time. it's much apreciated

 

[Chuck D. Bones]

The simple explanation is that all switching power supplies generate high-freq noise. The good ones make their noise at a frequency above the range of human hearing (>20KHz) and filter enough of it out so that it doesn't affect the pedals it's powering. Some pedals are more susceptible to switching power supply noise than others. The TC1044 is a switching converter and it can interact with a noisy power supply, making noise that is within the range of human hearing.

 

[Mcknib]

A batterys pure DC an adaptor converts AC from your wall socket to DC into your pedal

Some are filtered to stop noise because AC cycles between + and - constantly and are regulated to provide close to the listed output voltage e.g. 9v

Most cheap adaptors don't have regulators or filtering so can introduce noise or over voltage, which can cause oscillation, hum etc and once that gets into the circuit it can be amplified through the amplification stages and so on

If it's a +9v centre negative adaptor, set your meter to 20vdc put your black ground probe in the centre hole and touch your red probe to the outer barrel and you'll see what voltage Its putting out