SOLVED Muffler Noise Gate - No Gate - Help

[BuddytheReow]

Hey guys.

just finished populating the board on a muffler noise gate. I have it alligator clipped to check. Signal comes through just fine. How do I check if the “effect” actually works? Rub my hand up and down the strings and turn the pot simultaneously?

 

[Gordo]

Oh gawd no, you'll summon demons doing that

The easiest way is to set the threshold at about the midpoint and let a note ring on your guitar. At some point it should just drop to silence. If the threshold is too sensitive the gate will never close, and if not sensitive enough it will cut off the decay of the note before it should have. It's a matter of finding the sweet spot. If you have a noisy effect, like a phaser where you can hear the swooshing it might be a bit easier.

 

[BuddytheReow]

Thanks. I’ll give it a try and see what happens. I thought it would reduce the “hum” if I turned on an overdrive/distortion pedal, but it clearly did nothing. I’m also attaching a pic of the board

 

[Robert]

Where did you get your 2N5485?

 

[BuddytheReow]

Where did you get your 2N5485?

eBay, but I heard a rumor that a lot of em are fakes. How would I be able to tell? While testing nothing really happened when turning the pot.

Is there an equivalent I can use?

 

[BuddytheReow]

Anyone have any thoughts? @PedalPCB

 

[moonlightpedalbuilds]

I would double check the transistors and 4558. Check if the circuit is getting any power. Check voltage on the diode. Check the voltage on the IC pin 8 and ground.

 

[BuddytheReow]

I would double check the transistors and 4558. Check if the circuit is getting any power. Check voltage on the diode. Check the voltage on the IC pin 8 and ground.

How do I check transistors? Volt readings?

 

[zgrav]

How do I check transistors? Volt readings?

I suggest doing some google searches and searching the forums for some guidance. Those questions have been asked and answered a few times.

 

[BuddytheReow]

Just tried testing and here are my results. I did check for continuity on all the sockets. As another "test" I pulled q1 out of the socket and no sound, however I can remove Q2 and Q3 with no loss of signal. Can someone point me in the right direction? am I missing something?

IC
Pin1 4.7
Pin2 4.1
Pin3 3.1
Pin4 0
Pin5 2.94
Pin6 4.42
Pin7 4.41
Pin8 8.81

1n5817 diode 8.8V - red tested on cathode
Zener diode 4.7v - red tested on cathode

Q1 (2n3904) Pins read left to right
Pin 1 3.7v
Pin 2 3v
Pin 3 8.8v

Q2 (2n3904) Pins read left to right
Pin 1 0v
Pin 2 0.4v
Pin 3 3.75v

Q3 (2N5485) Pins read left to right
Pin 1 4.5v
Pin 2 4.7v
Pin 3 3.75

 

[BuddytheReow]

Posting more pics of my board if that helps anyone. Would appreciate some feedback. I’m stumped!!

 

[Gordo]

I'd be concerned with the 2N5458 being fake (not sure how you'd confirm or deny that) and using a 4.7v zener instead of the 5.1v

 

[BuddytheReow]

Need to circle back on the 2N5485 since this is above my skill set check for fakes. Here's the zener I used from Tayda, so I think im good there

1N4733 ZENER DIODE 1W 5.1V

VISHAY - Get It Fast - Same Day Shipping

www.taydaelectronics.com

FYI I have seen this same issue here on this forum, so something seems off...

 

[BuddytheReow]

Just to make sure I just ordered a few 2n5485 from Smallbear. I'll let everyone know if this works or not. I needed a few other things anyways, haha.

 

[Gordo]

Hope that's the fix. Board looks clean.

 

[Chas Grant]

Can you re-measure Q1 voltages? Pin 2 should be higher than pin 1. It looks as if you have the voltages on pin 1 and pin 2 swapped. Pin 2 should be about .6V higher than pin 1. If pin 1 is higher, then you need to find out why.

 

[BuddytheReow]

Can you re-measure Q1 voltages? Pin 2 should be higher than pin 1. It looks as if you have the voltages on pin 1 and pin 2 swapped. Pin 2 should be about .6V higher than pin 1. If pin 1 is higher, then you need to find out why.

I double checked q1. Pin1 is 3.7 and pin 2 is 3.0. Does this mean that pin2 needs to be higher or pin 1 needs to be lower voltage?

 

[BuddytheReow]

Ok. New problem. While going through the components and testing voltage before and after each, I notice a massive voltage drop in r103. 8.8v before the resistor and then 0.14v after. I checked the resistance and was about 22k which is correct. Why does this happen? I swapped the part out and the problem is still there...

I am this close to giving up on this one....

 

[Chas Grant]

If you have 8.8V before R8 and .14V after R8, then something is pulling down Vref_b. The question is what? Without power on the circuit, take resistance reading from downstream side of R22 and Ground. Without power on the circuit you should have a fairly high resistance, not sure what it would be, there are a few parallel paths to figure out. But if its low, then that would explain the .14V

 

[BuddytheReow]

Testing the resistance between the downstream of r103 (22k) and ground is about 300 ohms. Should it be? Seems very low