madbean cavedweller - power supply noise?

[bamslam69]

Hi everyone,
So I built this Madbean Cave Dweller back in 2016 and it had a fair bit of noise when I used a power supply. I ended up making Chromosphere's Power Pellet to reduce this, which it did nicely. I also made a quick 9V battery jack plug which worked too. No noise.
FFWD to yesterday. My wife gave me a Joyo JP05 rechargable power supply. Plug in the Cave Dweller and it gives out some mad power supply hissing when engaged. If I plug in another diy effect, Dead Astronaut's Tremshifter, no noise, so I'm sure I can scratch the supply as being the culprit.

Apart from hooking up the power pellet again, is there anything I should look at in the cavedweller circuit to reduce noise?
Thanks in advance!

[jimilee]

Lots of things really, got pics front and back along with voltages?

[bamslam69]

Thanks Jimilee,
I built it 3 years ago when I was just getting into this hobby. Happy to pull it apart and try to fault find it as it's a cool little delay.
I just tried it then, even when the supply is plugged in and switched off it makes a hum when turned on - when in bypass it's noise free.
Not totally discounting the power supply, but I think I should focus on my wiring first.
I think a plan is to pull it out of the enclosure and check for any shorts, but I'll check out the project PDF if there's volts shown there.
Might've answered my own question, but I'm all ears to any advice!
Cheers
Pete
Ps pics aren't working for me atm. Gimme a bit.

[jimilee]

Sounds good. I built several of those and kept one on my board. Definitely not a noisy pedal. Probably a loose connection. How are the input and out jacks. If it does it turned off, I would start there. And then test the switch with a DMM.


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[bamslam69]

Voltages below:
IC:
1- 4.96v
2- 2.489v
3- 0.0mV - (voltmeter bottomed out)
4- 0.0mV- (voltmeter bottomed out)
5- 2.939
6- 2.485
7- 0.611
8- 0.637
9- 2.493
10- 2.489
11- 2.490
12- 2.493
13- 2.493
14- 2.493
15- 2.493
16- 2.493
Q1
D- 6.99V
S- 0.451V
G- 0.1mV
REG
I- 9.28V
Gnd- 0.0
Out- 4.96V
Also worth noting that the lowest I could get the Voltage on the T1 trimpot was 6.99V.

[jimilee]

Have you tried a different pt2399 yet? They are a crapshoot sometimes. It may be time for an audio probe to see where the noise is introduced.

[bamslam69]

Cheers, I'll go through my parts bin and see what I can find, and have a play with my audioprobe.
Faultfinding is always fun. Off topic, I had an amp making weird noises occasionally when the reverb and chorus were engaged. It took a while before I realised the culprit was a dodgy power supply from some christmas lights on the same house circuit!
Anyway, I'll report back once I solve this. Still trying to post pics. I'm a bit slow on that front.

[jimilee]

The last place I lived, the power would surge at night and things would him when I tested them, very annoying. Hey, that clear light you have in that thing, what's that for? If it's to reduce noise in the circuit, switch it to a green LED. That may be a source for the noise.


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[bamslam69]

Ah right, it could be one of those "super bright" LEDs from Tayda. I'll check it out.
It's absolutely pissing down here in Sydney (a nice break from the drought), so it's a good day to stay in and get productive.
Thanks heaps for the replies.

[bamslam69]

Problem solved. Just a dodgy solder on the footswitch.
It's always something simple!
Thanks for the help Jimilee.

[jimilee]

Problem solved. Just a dodgy solder on the footswitch.
It's always something simple!
Thanks for the help Jimilee.

Nice! Happy to help.


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[bamslam69]

Wish I checked it properly before asking the question!

My fault finding regime now has, "poke and prod at my bad wiring & soldering" at Step 1.