Outdoor timer running to fast

Probably a faulty timer, but check to see if it has an automatic DST switch that happened to trip if it is one hour even.

That timer uses a simple synchronous clock motor timer that depends on the

The accuracy of the input doesn't guarantee the accuracy of the output if it isn't manufactured under precise (enough) tolerances...

The synchronous motor drives a set of fixed tooth gears which in turn drive the time display. "Manufacturing tolerances" won't cause the timing accuracy to change. The only probable cause for one of these timers to gain or lose time is either a) operating a 50 Hz timer on a 60 Hz supply, or vice-versa, or b) a power outage.

That assumes the gears have accurate tooth spacing -- if they're off, then the timing is off...

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Sometimes the manufacturers screw up and put the wrong timer motor into a piece of equipment. I have seen a 50hz motor in a timer that was supposed to for 60hz. If you take the timer out of it's case and look at the back you should be able to see the motor which will have the voltage and frequency printed on it.

I didn't stop initially to consider values, but (60/50)/(13/12) ~ 1.1 which is within 10% of the difference OP observed. Not an unlikely hypothesis. Maybe he ordered the wrong subseries???

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Actually, I'll agree on principle overall...was thinking of a short term variability possibly, but on the long term, it has to run a revolution per N cycles so not the OP's problem over 12 hours...

As noted elsewhere, the ratio of 60/50 to 13/12 is close enough to make one wonder if OP order the wrong series number and got a 50Hz model or perhaps it was just mislabeled...

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Have you checked if daylight saving time began in your area?

Not if your other mechanical clocks are right.

Probably.

I was in a W.W. Grainger supply house a few years ago where they had a new wall clock that had been returned by a customer. The clock kept perfect time, except for the fact that it was running backwards. The turkeys wouldn't sell it to me.

Those are pretty widely available novelties -- the barbershop I frequent has had one for quite a long time...

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I know that, but this one wasn't supposed to be running backwards. I've seen the novelty clocks that are numbered anticlockwise/counterclockwise. The odd clocks catch your eye on a subconscious level then you look more closely and remark WTF.

Bet me! :)

The one in the barbershop is also just like that...

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Chuckle. A house my family had for a couple years back in the late 60s had a built-into-the-paneled-wall kitchen clock like that. (Shaft stuck through paneling, little brass squares that served as the numbers stuck to paneling around it. Very Trendy for about a month in '66) Every time the power blipped during a thunderstorm, it would start running backwards. Nobody ever cared enough to pull it out from the access hatch in the pantry behind and diagnose it. We just ignored it, or if company was coming, flipped the breaker off and on.

aem sends...

Oh, I believe you, I've seen stranger things. The little old barbershop I frequent on a semiannual basis (whenever I start looking like Hagar The Horrible) has no unusual artifacts. Perhaps I shall get them one.

Don't you just love it when devices act in an anomalous fashion?

I'm betting the one you saw was probably modified by the countermen themselves as a lark, not that it was "returned"...

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Neither (a) or (b) would cause a synchronous motor timer to gain an hour; (a) would cause it to gain 2.4 hours and (b) would cause it to lose however many hours the power was off. If the gear tolerances were off, however (tooth count or diameter off a smidge, it could well gain an hour in twelve.

replying to timnels, Kenny wrote: I don't know what sort of timer is a T103. But I have a very old (but excellently designed) Oasis Dundee 9 Station irrigation pump controller, which very recently developed an issue where its digital clock was running too fast. About an hour later, the clock would be something like 7 minutes or so ahead of 'actual' time of day. My controller doesn't appear to have a 'crystal' component on the circuit board. But it normally keeps the correct time even when AC power is switched off, and powered by a back-up battery. So there must be an oscillator circuit in my board's circuit - somewhere. The beauty of my particular irrigation controller is that it only has two electrolytic capacitors in it. I changed the smaller electrolytic capacitor (a 100 microFarad one). No improvement. I then changed the larger 470 microFarad one, which fixed the issue. As we know, due to the limits of our technology - electrolytic capacitors are probably the number 1 cause of electronic circuit failures in circuits. Since my particular board had only two capacitors, it allowed me to sort things out fairly quickly. The interesting thing is - the electrolytic capacitors do not necessarily need to be bulging (or physically broken) when they go bad or fail. But, they often will have a bulging top if they've failed. So, if your timer has electrolytic capacitors in it.... check them out.