SOLVED Cataclysm Delay with no echo, but....

[SteveScott]

I'm getting some odd behavior out of my cataclysm delay. All four controls seem to be working, but there is no echo. If I turn the feedback up, it will self oscillate. And while the oscillation is going on, the time, mix and tone controls do what you would expect them to do. But there is no initial echo. So I'm wondering if that is a symptom of a bad PT2399? Perhaps some other obvious issue? I used two 10k resistors for R20 and both the 5k pots are 10k with a 10k resistor from 1 to 3. Other than that, everything is what was called for.

 

[Cybercow]

While the photos are not as clear as they could be, it appears some of the pot legs are solder-starved and/or cold. Try re-flowing the solder (and add a touch more with flux) at the pot lugs. Let us know how that works.

 

[SteveScott]

While the photos are not as clear as they could be, it appears some of the pot legs are solder-starved and/or cold. Try re-flowing the solder (and add a touch more with flux) at the pot lugs. Let us know how that works.

Thank you for that. I'll give that a try. Two of the pots are soldered from the top side and two are soldered from the bottom, so it may appear worse than it is. However, I will clean them all up and flow some more solder in there. Also, I'll try to get a better picture with daylight.

 

[BuddytheReow]

I agree. Clean up your solder joints, clean the board with some 90% IPA (don't get any inside the pots) and repost your pics.

 

[chongmagic]

Yes IPA is your friend and also check this solder joint.

 

[SteveScott]

I cleaned things up a bit, added some solder {including the spot chongmagic pointed out, and still getting same results. Attached are a couple of pictures. I have more pictures that may need to be compressed a bit in order to upload.

And now that I uploaded these pictures I see at least one cold solder on a cap. I will go fix that real quick.

 

[SteveScott]

Ok, now that I got that electrolytic cap replaced here's an updated picture.

(I should mention that I'm still having the same problem, and I truly appreciate all the help.)

 

[Cybercow]

If you have and can use an audio probe, check for signal at pin #16 (input) and pin #14 (output) of the PT2399.

Curious that no sockets were used for the chips. Makes it so much easier to quickly & easily swap out for testing. The PT2399 is common chip, but some vendors may be unscrupulous and sell marginally operative or even fake chips these days. From where was the PT2399 acquired? (If you don't mind my asking.)

 

[SteveScott]

If you have and can use an audio probe, check for signal at pin #16 (input) and pin #14 (output) of the PT2399.

Curious that no sockets were for the chips. Makes it so much easier to quickly & easily swap out for testing. The PT2399 is common chip, but some vendors may be unscrupulous and sell marginally operative or even fake chips these days. From where was the PT2399 acquired? (If you don't mind my asking.)

The PT2399 came from Tayda. I've made other delays with the same chip from Tayda with no issues, but there certainly could have been a bad one in the bunch. I think it's more likely that I may have damaged it on the install (if there is a problem with the chip) since I didn't socket it. And this is the first time I choose not to use a socket, not really sure what made me decide that. But if I end up pulling it, I will definitely install a socket. I'll make up an audio probe tonight and let you know the results.

 

[SteveScott]

This took way longer than I expected, but finally got around to this. There is no signal at pin 14 or 16. Just to be thorough, there is no signal at any of the pins on the PT2399. There is a very faint high pitch at pin 9 and some odd sounding echo at pin 15. There is also signal on the TL072 at pins 1 and 7. Thanks so much for the help.

 

[SteveScott]

After thinking about it a bit, I'm guessing this is where my problem likely lies. Any thoughts? Thanks again.

 

[SteveScott]

This is way too long to wait, but I did finally figure this out. It turns out that the PCB had no continuity from the negative side of C7 to R10. I ran a jumper wire on the back side of the PCB and presto, works beautifully.