Troubleshooting Atari Punk Console

[greenacarina]

So, I recently built the Atari Punk Console as a fun project for me and my son. Teaches him about soldering and the interaction of some basic components and he has something fun to noodle around with when he's done.
I ended up building 2 of these...one on my own then one with my son. His works great and we had a lot of fun making it....but mine has an issue I can't seem to track down.
I used Dragonfly's stripboard layout as my guide. The pot shown on the right side of the diagram (not sure how to describe what aspect of noise it controls) is only effective through the first quarter to half of it's range (depending on where the left pot is set).
From 0 ohms to about 100k ohms it does what it should, then fades out quick (with some quiet sputtery/farty noises). If the left pot is up higher (closer to 500k ohms), I can get action out of the right pot up to about 250k before it sputters out.
Any ideas or direction I should be looking?

Thanks!
Chris

[njkmonty]

"my son and I "

[nocentelli]

If that's a grammatical correction the original poster has it right, although "for my son and myself" would be even better.

[greenacarina]

Well, I took your suggestion and spoke nicely to my project....carefully using my correct grammar. Didn't seem to help.
Any other suggestions?

[Earthscum]

Quick questions: Did you socket the timer? (if so, try the timer from your son's and make sure you didn't do something to it). Did you use the same IC on both builds? ie: NE555 vs. TLC555. If not, same thing... try the one from your son's build, or (if soldered in) try to source another like it to try.

EDIT: meant 556 (unless you did the 2 555's). Actually have to look that up to see if they make a CMOS 556....

EDIT: Yep.

One More: If you can, make sure your pot is good. I've fried a couple getting soldering gunk that flowed too far. Make sure that it is giving proper range of readings (with a DMM, of course).

[greenacarina]

Yep, it was a 556. It was socketed on both projects....I will try swapping them.
I did check the range of the pot (to make sure I soldered the 2 lugs together correctly, etc...) and it's right where it should be.
Will have to talk my son into bringing his APC back over from mom's house...he's having a ton of fun with it!

Chris

Quick questions: Did you socket the timer? (if so, try the timer from your son's and make sure you didn't do something to it). Did you use the same IC on both builds? ie: NE555 vs. TLC555. If not, same thing... try the one from your son's build, or (if soldered in) try to source another like it to try.

EDIT: meant 556 (unless you did the 2 555's). Actually have to look that up to see if they make a CMOS 556....

EDIT: Yep.

One More: If you can, make sure your pot is good. I've fried a couple getting soldering gunk that flowed too far. Make sure that it is giving proper range of readings (with a DMM, of course).

[Earthscum]

Another thing to apparently watch for with stripboard is bridging at the ends where the copper didn't etch off. You might take your meter and check  to make sure you don't have bridges.

[petey twofinger]

u could also apply presure on the chip . there are bad sockets going around , they dont make proper contact ...

is the pcb flexed at all ?

that happened once ... it has to "not be bowed at all ' ...

good luck , let us know what it was !