SOLVED Paragon Whistle/Scream

[piapium]

Unfortunately another pedal hasn’t worked at first try again.

1st channel engaged:
tone pot is full -> whistle

2nd channel engaged:
tone pot is full -> whistle

Both channels engaged -> whistle on any position of the pots.

Will upload pictures and a video tomorrow.

Appreciate any help. Thanks!

 

[Chas Grant]

Just curious, Can you confirm your 3362 Trimmers are 3362 -1- 503 = 50k
If 504 = 500k
If 502 = 5k

That's a very valid point!

 

[piapium]

It’s 503 - 50k

and when I removed the ics, pin 3 is around 4.69-4.70 for both ics. 1 and 2 is 0 volts for both again.

 

[piapium]

And for the first capacitor- c1 the board says 10n but the documents say 22n. Could it be the problem? I put a 22n on the board.

 

[Travis]

Did you try another power supply?

Some build make this kinds of noises with switching power supply.

 

[piapium]

I’m using standard boss type 9v adapter for the pedal. Haven’t tried a 9v battery. I’ll try now.

 

[piapium]

tried with battery, still same.

 

[Chas Grant]

C1 is a coupling capacitor, it is preventing any stray DC voltage from getting into 1st op amp stage from the input. It also forms a high pass filter with R2, this will attenuate low frequencies, but the cut off freq is around 7 Hz at 22n and 15hz at 10n. Both freq's are below the frequency range of your hearing so there is really no effect, also 8 Hz is negligible. So no difference between 10n and 22n.

With IC1 and 2 removed, pin 3 voltage should be whatever Vref is, it is not. Vref is 9V. Remove power from circuit. Check resistance between IC2 pin 3 and R2, both sides of resistor. You should have 0ohms on one side and 1Meg on the other side of R2. Then check IC1, pin 3 and both sides of R16. Should measure same as IC2. Also check pin 3 to ground, it should be open. Pins 1 and 2 should be 0volts with IC removed.

 

[piapium]

Have I been checking wrong? Should I use v~ 200? I’ve been checking according to the above picture. R2 and R16 are as you said. Pin 1-2 are 0 also.

 

[Chas Grant]

View attachment 7041
Have I been checking wrong? Should I use v~ 200? I’ve been checking according to the above picture. R2 and R16 are as you said. Pin 1-2 are 0 also.

That’s DC voltage, with power removed it will be 0. Place meter on 2000k for resistance and check. That’s in the bottom blue section of meter dial switch. Always check resistance with no power. At 9 volts it drives your meter nuts, but at 480Vac it blows the meter up???

 

[piapium]

??? no I’m not asking for resistance, asking for voltage. Am I checking voltage right? I’ve been checking according to the picture.

 

[Chas Grant]

Nope, check the resistance between the points, Trying to figure out why you only have 4.5 volts at pin 3. It should be 9V. Making sure the connection is good and also want to make sure there is no path to ground from pin 3. The 4.5V is baffling.

 

[piapium]

Resistance is ok. It is as you said. I can’t figure out why it’s 4.5v either. Gonna lose my mind.

 

[Chas Grant]

This has me scratching my head. Put IC1 and 2 back in, remove IC3 and power it up and see if it still whines. Removing IC3 will have the pedal running at 9V instead of 18. If the whine is gone, try a different TC1044.

 

[piapium]

Already tried. I can use both channels but when I turn up volume gain and tone it starts whistling. But it is usable up to a point. When I touch guitar strings and output jack it whistles.

 

[Chas Grant]

So what happens if you play an open string? Does it whine or is it only when you touch strings that it whines

 

[piapium]

Only if when I touch the string it whines. If I touch the strings and output jack it whines. And when touch the strings hum gets louder. I’m recording a video.

 

[Chas Grant]

Take a picture of input output jacks

 

[music6000]

Take a picture of input output jacks

Now, this is a valid point!

 

[piapium]

This is input

This is output

 

[piapium]

IC3 is out for the video but it is same with the ic3. nothing changes.