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Good afternoon everyone.
I have a great project, however my skills and knowledge on the subject are limited. Let's say that I inherited from a relative of mine, my father's brother, a watchmaker, this beautiful machine from about 1974.

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Although it is very well cared for, it does not work. I have inspected and I think the problem is with a zener diode (BZY92C10). Or a pair of transistors that activate the solenoid that hits the cylinder with the helical track that prints the succession of points.

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PCB1.  The side tracks is rotate to match

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PCB 2 Is rotate o mirror to match

The motor turns and the paper strip advances. But the characteristic sound of the impression tapping is not heard.
In fact I was able with the help of a tip to check current of 12-24 volts, I could see that at the output to the printer / solenoid, a pulse corresponding to the beat of the clock is generated. But it seems that the current is not enough to drive the solenoid coil.
The solenoid coil works if I activate it with a 9 volt battery. In other words, you can hear the “click”.
If any of you wish to join me in this project, I would greatly appreciate his help.

Thanks

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As this machine is almost 50 years old one of these you want to be suspicious of is electrolytic capacitors. They do lose their capacitance with time.

 

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