Creamery Buzzing

[IPv6Freely]

LED comes on, but there is nothing but a low volume buzz through my amp. Another day, another pedal that doesn't work...

Board pre-pots:

Solution for pots not having pins narrow enough to fit into PCB holes:

Final assembly:

Do you see anything obviously wrong?

 

[Feral Feline]

D1 is in backwards.
Q1 transistor is in backwards — probably, depends on its pinout.

 

[IPv6Freely]

D1 is in backwards.
Q1 transistor is in backwards — probably, depends on its pinout.

FML. I noticed Q1 and swapped it. I didn't notice D1.

I really need to be more careful building these things. Components being wrong or the wrong orientation is inexcusable.

 

[IPv6Freely]

Okay, now Q1 and D1 both fixed. Still just buzz, and only while the COMPRESS knob is turned beyond half way, otherwise nothing at all. Bypass is fine.

 

[music6000]

It really is Wurth going over the PCB thoroughly & and checking orientation if it doesn't fire up!
That IC 4 looks suspect the way it's sitting.
How did you determine which way THAT 2159 goes?

 

[IPv6Freely]

It really is Wurth going over the PCB thoroughly & and checking orientation if it doesn't fire up!
That IC 4 looks suspect the way it's sitting.
How did you determine which way THAT 2159 goes?

That's a good question. I guess I should check the datasheet on the THAT2159 because I have no idea and made an assumption there.

I'll take a look at IC4

 

[IPv6Freely]

Yeah looks like the THAT2159 are the right way. Pin 1 is on the left, and according to the datasheet pin on the left is IN and the schematic confirms that.

 

[IPv6Freely]

IC4 reseated as well... no change. I guess its back to checking voltages and continuity...

 

[music6000]

IC4 reseated as well... no change. I guess its back to checking voltages and continuity...

Can you recheck your Pot legs are all connected to the PCB via the leads???

 

[IPv6Freely]

Can you recheck your Pot legs are all connected to the PCB via the leads???

Yeah that will be the first thing I check - knowing that it's a bit of a hack job its the most likely thing to be an issue.

 

[music6000]

Yeah that will be the first thing I check - knowing that it's a bit of a hack job its the most likely thing to be an issue.

Where did you get that J201?

 

[IPv6Freely]

Where did you get that J201?

eBay...

 

[Feral Feline]

It really is Wurth going over the PCB thoroughly & and checking orientation if it doesn't fire up!
...

Not the Wurth thing possible to go wrong, though — at least the magic smoke is still contained.

 

[IPv6Freely]

I tested the J201 I got and I'm getting the correct values for Idss (0.27mA) and Vgs (0.79V) so it shouldn't be the J201 that is the issue.

 

[music6000]

Test for Continuity on these Matching colours: