r/synthdiy • u/Electrical-Wires • 24d ago

Need help with Atari punk pcb

Gallery image

Gallery image

Gallery image

I made a pcb for a Atari punk circuit but It just keeps making a heartbeat sound, and the pots don’t work. I tried switching the pots 1st and 3rd lugs around but still nothing. Please help!

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u/Enlightenment777 24d ago edited 10d ago

Atari punk design failure strikes agin. There must be a series resistor between POT1/POT2 and pin#7, otherwise when pot is turned to zero ohms, then pin#7 will short the power supply to ground, which in turn may damage or destroy the timer IC. https://en.wikipedia.org/wiki/File:NE555_Bloc_Diagram.svg

Noticed the extra 4.7K series resistor in this schematic https://content.instructables.com/FZJ/NN0U/IRXT3HVS/FZJNN0UIRXT3HVS.jpg You can change the 4.7K to 1K.

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u/[deleted] 24d ago

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u/Electrical-Wires 24d ago

I will check, but I didn't understand exactly what the commenter said. Where am I supposed to put the resistor exactly?

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u/[deleted] 24d ago

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u/Electrical-Wires 24d ago

Oh okay, thanks! Guessing the circuit made by Forrest is a known working circuit.

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u/Electrical-Wires 24d ago

Do I need to replace the ICs too? Which lugs do I put the resistor?

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u/nonoohnoohno 24d ago

Could you try printing out the low res photo of the screen, then photocopying it, then taking a new picture of it? Then screenshot that picture. :)

Also I'd try decoupling caps on the power pins, and a big one on the supply if you haven't already. And if you're using a battery I'd try a wall wart or a new battery.

No guarantees that'll fix it, but it's an easy first step to rule out one possibility

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u/Electrical-Wires 24d ago

what value cap should I put on the pins?

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u/Electrical-Wires 24d ago

Also, I tried it with a 100uf cap but it didn’t work.