Low Tide - Problem with 5V power supply circuit (maybe?)

[sadalbari]

Hello everyone!

Thank you already for taking the time to even look at my problem.

I built the Low Tide as a third build and while both the Son of Ben and Duocast turned out spledid this one gives me a headache:

When the output is connected to an amp and I connect it to 9V power it first starts making soft noises like – even if it may sound stereotypical – soft waves on a shore. Within a few seconds it starts producing a heartbeat-like popping sound „du-dup…. du-dup… du-dup…. repeat“. But it never passes a meaningful signal while engaged (LED on).

I got as far as identifying that IC1 (the LM78L05) becomes very hot and if i cool it a bit the popping sound disappears. The „output“ lug of the IC measures only 1,3V against the common lug.

So, since I understand it should supply 5V I suspected I might have fried the IC soldering it and ordered a few replacement LM78L05s, alas to no satisfactory resolution: New voltage regulator, the same problem.

So I suspect I must have messed up somewhere else. Do you have an idea where that might be or provide me with a strategy to debug this issue?

Attached you’ll find some pics of the front and back. I singed capacitors 36, 38 and 30 a little desoldering the IC but they still measure fine and while the 1M double pot is quite close to the back of the PCB it doesn’t touch and short anything there.

If I should supply any additional information, let me know.

Thanks again for reading and I’m looking forward to ideas.

 

[Robert]

CD4046 in the bottom right corner is installed upside down.

 

[sadalbari]

CD4046 in the bottom right corner is installed upside down.

View attachment 37436

Oh boy, what a blunder... This did in fact solve the initial problem. Thanks for the quick reply.
Popping noise gone, 5V on voltage regulator and the temperature is reasonable.

Yet now all I get when turning the mix up is a static hiss. Do you consider it likely putting the chip in upside down may have broken it or something else? The volume control works and the dry signal is passed through just fine.

Otherwise I would try and trace it along the signal path with an oscilloscope to see where it breaks?

 

[Robert]

It's possible, since the 4046 generates the clock for the BBD.

Have you tried adjusting the BBD bias trimpot?

 

[sadalbari]

Hmmm... adjusting the BBD bias trimpot doesn't result in any audible change.
I got myself a replacement CD4046 and replaced it but that didn't change anything either.

Still, on the wet signal all I get is a high pitched, yet not particularly loud noise.

If you have any further ideas I am thankful, otherwise I'll give the cause a more in-depth chase in the coming days.

 

[hamerfan]

You should use dust covers on the pots to avoid shorts.