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TonyDuell · 5th Aug 2017, 9:32 pm

Yes, my timer makes a bit of noise too. It's easy enough to disable it when testing, the motor is wired via a couple of small faston terminals to a tagstrip on the chassis rail. I do find the power supply for that motor to be typically Philips too. Not run off the primary of the mains transformer (as an autotransformer) and not run via a dropping resistor. No, it's a dropper capacitor with a VDR in parallel with the motor, I guess to allow it to run off any sane mains voltage.

The linkage in my timer that does the carry from the minutes drum to the hours drum is sticking. I will investigate that.

But I first need to look for the autoreverse fault (yet another oddity, there's a monostable with an NPN and a PNP transistor cross-coupled) and the audio fault. I want at least to know the approximate area of the latter.

5th Aug 2017, 9:32 pm	#29
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,225	Re: Philips N4450 Yes, my timer makes a bit of noise too. It's easy enough to disable it when testing, the motor is wired via a couple of small faston terminals to a tagstrip on the chassis rail. I do find the power supply for that motor to be typically Philips too. Not run off the primary of the mains transformer (as an autotransformer) and not run via a dropping resistor. No, it's a dropper capacitor with a VDR in parallel with the motor, I guess to allow it to run off any sane mains voltage. The linkage in my timer that does the carry from the minutes drum to the hours drum is sticking. I will investigate that. But I first need to look for the autoreverse fault (yet another oddity, there's a monostable with an NPN and a PNP transistor cross-coupled) and the audio fault. I want at least to know the approximate area of the latter.