Why is this 555 timer getting stuck ?

[MathWizard]

I made a dual tone alarm type circuit for in a wire finder/toner/tracer, with a NE556 timer. A main freq of about 1700Hz and a long freq of about 0.33Hz. I added an LED that blinks with the 0.33Hz part.

And on the breadboard it worked ok for a few days, and never had it lock up. But a proto-board, from time to time, the LED gets stuck on. I thought maybe it was current from the other 1/2 circuit, and added a diode, but it's still happening, so it's the 1st output getting stuck high.

But then I can turn it off, let C1 discharge to zero, turn it back on, and it can get imediatly stuck on again ?? But wait a few minutes, and it seems to be normal again. For a minute anyways, I just watched C1 ramped up , get stuck there for a while, then cycle 2-3 times, and now it still stuck high.

The other side remains normal, ticking away at 1900HZ atm. But now only hear just that tone.

This time I wasn't touching it at all, I thought it was related to me flicking an output switch, or moving wires.

[daveatol]

If it's not oscillating, I'd check connections on pins 2, 6, and 7, as well as R1, R2 and C1. The circuit, as drawn, looks fine to me, so the issue would be in your wiring.

Do you have a photo of your circuit on the protoboard?

[MathWizard]

No photo, but yeah the sim works too. I'll have closer look at the soldering.

[Renate]

C1 is probably leaky.
Jumper another 100k across R2 (as a test).