>I checked the resistance between pin 22 on U4 and pin 2 on U5, and it's undetectable.

As in zero resistance, or infinite resistance?

>Doesn't U5 have only 24 pins?

Yes-- thinking about pin 24 and U5 at the same time is a bad idea, apparently.

One thing to try at this stage: swapping chips.

Swap U2 and U3, and swap U4 and U5. See if your problems move or stay in the same places.

> As in zero resistance, or infinite resistance

zero resistance.

> One thing to try at this stage: swapping chips.

Nope, doesn't seem to make a difference.

I've been touching up the solder joints on the U2/3/4/5 sockets, and the problem has gotten much less bad, and is *so close* to going away,

It's kinda hard to tell, though, because it has always gotten much better the longer I leave the board on, so I'll think I've just about fixed it, leave it off and come back, and it's back again.

>zero resistance.

Good.

>Nope, doesn't seem to make a difference.

That means that (1) the problem isn't in your chips are good and (2) it's probably not a matter of failing to insert them far enough in the sockets. There could still be a point where the socket is not making a good connection to the chip or to the circuit board, however. If you look at the sockets while the chips are in place, make sure that the visible part of the socket metal looks the same at each pin.

>it has always gotten much better the longer I leave the board on

Well, that's interesting. If it's a problem that changes when the board warms up, you might try wiggling the different parts to see if any chip or other component affects it.

Sorry for posting after so long, but I came back to my peggy 2 after almost a year to use it in a different project, and was still wondering what was causing the problems I was having earlier.

I figured I'd try replacing the power supply and see if it helped. I found my old adjustable wall wart style power supply and set it to 4.5V, hooked up the appropriate barrel connector, and the problem completely goes away!

Do you think maybe I get a bad power supply?

I think that we do have a fix for this problem, which is to add a 1 uF (or so) capacitor in parallel with (or instead of) capacitor C10. If you have one handy, you can try that out. If not, please contact our webstore to request one.

Sure enough, that fixed it right up! I replaced c10 with a 1 uF tantalum capacitor, and the problem goes away completely, no problems no matter what power supply I use.

Thank you for your help! Though I'm curious, could you explain a bit more about what was going on?

Great-- I'm very glad that it's working.

Our best guess is that there's a voltage droop at that chip, possibly due to so much current moving elsewhere on the board. The cap stores enough charge to even things out for that brief moment. We'll be putting the new cap values in our next batch of Peggy 2 kits, of course.