The best idea i have here is the try and confirm which side of the driver board is at fault and testing the 555 ic is the best way to do this. But you need to test it when the switch test is working and also when not to compare results
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Hi Jim @myPinballs
I can confirm with the logic probe I initially get a nice steady pulse, but as the test display on the dmd starts going mad as the switch fails, I lose the pulse all together and just get a logic 1 - so it is on the 555 side of the circuit.
Is this going to be C8, C9 or the 555 itself do you think ?
Cheers
kev
I can confirm with the logic probe I initially get a nice steady pulse, but as the test display on the dmd starts going mad as the switch fails, I lose the pulse all together and just get a logic 1 - so it is on the 555 side of the circuit.
Is this going to be C8, C9 or the 555 itself do you think ?
Cheers
kev
Ok good i think we are making progress. So i would be tempted to change the 2 caps first seeing as the issue is appearing after a preset time. I would also double check diode D3 (or just swap it out to make sure) and check resistor values R9,R10,R11. Unlikely to be a resistor though unless there's a cold solder joint. (resistors are usually only an issue in power circuits where they burn up and increase resistance) Then retest, if no good change (and socket) the 555. I have seen them wear out over time. Its hard to pinpoint which part could be doing this, but we've got it nailed down to 3 or 4 parts which isn't bad going now.
Jim
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Thanks Jim will do