Seth Thomas electric runs too fast

[eskmill son]

Only thing I've done to this one is replace the mains cord. Old one was in really bad shape. Once replaced and juice applied, it runs too fast (about 20-30 sec in just about 5 min running). My first thought was maybe the clock was designed to run off 50hz and since electronics are not my forte (go figure as I am now an electric clock fan). As I take a better look at the tag, it does say 60 cycles.

Is there anyway to adjust the speed of these movements?

 

[Berkshire Vet]

Hello Dan,

In general there is no way to adjust the speed of an electric clock. Running a clock with a 50 hz motor will be about 1 minute fast, when connected to a 60 hz main. Only seeing 20-30 seconds over a 5-minute interval, would indicate something binding in the motor and drive.

The vintage electric clocks used synchronous motors that lock-in to the frequency of the mains. The electric grid very closely monitors system frequency and it only varies by a tiny amount. This accuracy made it ideal for early electric clocks where the motor could be locked in and turns as a function of frequency. My best guess is you have something internally that is pinching the gear drive.

Good Luck !!

Mark

 

[gvasale]

That may not be an original motor. Seems to me, binding somewhere should slow it down.

 

[eskmill son]

My thoughts as well in regards to binding (would run slower). Motor runs smooth and quiet, just too fast. Haven't found any information in my google searches or books that I have on this model and what motor it would originally come with to verify.

Thank you both for your valued input

 

[JeffG]

Have you recently switched to using solar power? Sometimes the inverter will produce electricity at 66 cycles. I think it is so that the controller can differentiate between grid power and solar power in a grid-tied system. I'll know more after I talk to the solar guys about my system (my clocks are running a bit fast).
-Jeff

 

[eskmill son]

Have you recently switched to using solar power? Sometimes the inverter will produce electricity at 66 cycles. I think it is so that the controller can differentiate between grid power and solar power in a grid-tied system. I'll know more after I talk to the solar guys about my system (my clocks are running a bit fast).
-Jeff

Nope, I'm old school. That is interesting, but shouldn't the clocks be able to adjust automatically for such slight changes?

 

[JeffG]

Nope, I'm old school. That is interesting, but shouldn't the clocks be able to adjust automatically for such slight changes?

I don't guess so. Mine aren't speeding up nearly as much as yours- maybe a minute every day or two. For synchronous motors the AC cycles are like pendulum rates for mechanical clocks.

 

[eskmill son]

I did find through google searching of that mine is an S1 Westclox motor produced by Sangamo. Maybe I'm lucky and will find another motor if this one cannot be figured out.

 

[gvasale]

Synchronous motors synchronize to the line frequency..The only thing that could.change that is if power companies were asleep.and let.their controllers run amock. A VFD might help depending on it's design. A DVM that can read frequency will give you a better answer. It might not be worth the cost.

 

[Berkshire Vet]

Hello Dan,

In general there is no way to adjust the speed of an electric clock. Running a clock with a 50 hz motor will be about 1 minute fast, when connected to a 60 hz main. Only seeing 20-30 seconds over a 5-minute interval, would indicate something binding in the motor and drive.

The vintage electric clocks used synchronous motors that lock-in to the frequency of the mains. The electric grid very closely monitors system frequency and it only varies by a tiny amount. This accuracy made it ideal for early electric clocks where the motor could be locked in and turns as a function of frequency. My best guess is you have something internally that is pinching the gear drive.

Good Luck !!

Mark

Ohhh doggoneit....reading Mark reading. I read fast and thought slow.

 

[Berkshire Vet]

Synchronous motors synchronize to the line frequency..The only thing that could.change that is if power companies were asleep.and let.their controllers run amock. A VFD might help depending on it's design. A DVM that can read frequency will give you a better answer. It might not be worth the cost.

The power company very closely monitors frequency of the grid- trust me. I spent nearly 25 years 'making' the big juice . They don't really have an immediate way to control it either. It's purely a function of the design of the base load generators. The only thing they typically adjust is the VAR load, by tweaking the voltage regulators among a number of units so they share the burden. The VAR loading is sort of a parasitic load, caused by the magnetic field surrounding AC power lines. It's negligible for house current, but significant of course, in a grid system. During overload conditions amperage goes up, voltage goes down and if it goes down far enough, frequency will start to vary. This happens when there is insufficient voltage to keep the generators synchronized (locked in electrically) to the grid, and they can undergo a disastrous event called slipping a pole, resulting in a massive increase in amperage and nearly immediate burn out of the generator. As our friend stated above, one would need a Variable Frequency Drive to change the speed of an AC motor. They are usually found on larger motors requiring an ability to speed up or slow down operations.

As our friend correctly stated, binding in this case would slow it down. Oddly enough, the Jefferson clocks I restore can actually have a failure where the indicated time is running fast, but that's an issue internal to the drive.

I think I would try to find a replacement motor that is carefully checked for that clock. It's a weird issue.

Good Luck
Mark at Bugsy's Dad Enterprises

 

[davefr]

It's impossible for a synchronous motor's main shaft to run faster then it's designed speed assuming the power grid is also at exactly 60 Hz. It's dictated by RPM (at primary shaft) = Hz X 60/Number of Poles. In almost all cases its loose hands or hands contacting each other as they pass that causes the illusion of running fast. The other cause can be a badly worn movement/gearing where a hand can slip on the downward 12:00 to 6:00 arc yet travel normally from 6:00 back up to 12:00. I believe those Sangamo motors don't have any reduction gearing contained within the motor so I would look elsewhere in your troubleshooting.

 

[eskmill son]

It's impossible for a synchronous motor's main shaft to run faster then it's designed speed assuming the power grid is also at exactly 60 Hz. It's dictated by RPM (at primary shaft) = Hz X 60/Number of Poles. In almost all cases its loose hands or hands contacting each other as they pass that causes the illusion of running fast. The other cause can be a badly worn movement/gearing where a hand can slip on the downward 12:00 to 6:00 arc yet travel normally from 6:00 back up to 12:00. I believe those Sangamo motors don't have any reduction gearing contained within the motor so I would look elsewhere in your troubleshooting.

Good info sir. I'll take a look tonight when I get back home for any slip on the hands, but from what I remember, they spin at constant rate on the down/up slopes.

Also will be searching for a donor motor on fleabay.

Thank you for the info!!!

Dan

 

[eskmill son]

Have an identical motor on the way. Will update once in hand and installed/tested.
Thanks everyone for input and help with ideas.

 

[eskmill son]

Well, got a replacement motor today. Not only does it run backward, but also runs 10 sec too fast (same as original motor).

The backward rotation I'm sure is due to the fact it came out of a movement that required the different rotation based on the gearing on the movement. Not exactly sure how I could change the direction if it did rotate at correct speed.

Still puzzled how two motors could be 10 sec too fast.

 

[Molson3003]

Well, got a replacement motor today. Not only does it run backward, but also runs 10 sec too fast (same as original motor).

The backward rotation I'm sure is due to the fact it came out of a movement that required the different rotation based on the gearing on the movement. Not exactly sure how I could change the direction if it did rotate at correct speed.

Still puzzled how two motors could be 10 sec too fast.

 

[Molson3003]

Search for this

HELP Sangamo Replacment

Davefr already said what to look for as far as the clock gaining time

 

[Molson3003]

Search for this

HELP Sangamo Replacment

Davefr already said what to look for as far as the clock gaining time

If the clock now runs backwards, I suppose the issue is now the clock losing time. Expound on this as it may pin point the issue

 

[eskmill son]

Well, I was finally able to at least identify the clock from a 1938 catalog. It is a No 4E Senate

 

[Wimberleytech]

Well, got a replacement motor today. Not only does it run backward, but also runs 10 sec too fast (same as original motor).

The backward rotation I'm sure is due to the fact it came out of a movement that required the different rotation based on the gearing on the movement. Not exactly sure how I could change the direction if it did rotate at correct speed.

Still puzzled how two motors could be 10 sec too fast.

Well, a motor can run at many different speeds depending upon its design (number of poles). I suspect that it is the wrong motor. Can you post more pictures of the motor by itself?

 

[Molson3003]

i suppose i wasn’t very clear, the same issue came up before and was resolved in the post /thread i referred to.

i am doubtful eskmill has the wrong motor/rotor as it obviously fits, the issue with the gaining of time was present before, and likely nothing to do with the rotor. In fact, because the issue is still present with the new rotor, I am fairly certain the two are the same

I know with telechron rotors, the simple mistake of putting the coil on backwards will cause the shaft to rotate backwards.

 

[gvasale]

once more, check line frequency. They don't regulate to exactly 60HZ, but close. Say horseshoes and hand grenades.
There are power conditioners which are far better than what the grid does. Not really inexpensive.

 

[Wimberleytech]

once more, check line frequency. They don't regulate to exactly 60HZ, but close. Say horseshoes and hand grenades.
There are power conditioners which are far better than what the grid does. Not really inexpensive.

Don't think so. The OP said " about 20-30 sec in just about 5 min running" On average over a long term, the frequency of the power grid is extremely accurate.

 

[eskmill son]

I'll check exactly how much faster it runs again once I have it back together with original motor.

Photos below show original motor on left of photos and replacement motor on right. The two motor do have a few differences. Obviously the gear is different since they go on two different movements. When I swapped motors, I simply took the rotating part of the motor (with gear) from original motor and put onto new motor. You can also see motor cases vary slightly. The leads on new motor were barely long enough to reach connections and you can see there are positioned differently on each motor as well.

I did visit the old thread (my father actually had a lot to offer here as well). Thanks Molson3003
HELP Sangamo Replacement

I've read through it several times and couldn't come up with anything significant that I can try.

 

[Wimberleytech]

I am familiar with that motor. Replaced one in a different ST mantle clock recently. Those motors are hard to find!
I think it runs at 600 RPM.

 

[gvasale]

Don't think so. The OP said " about 20-30 sec in just about 5 min running" On average over a long term, the frequency of the power grid is extremely accurate.

Yes. Over the long term. Web searches suggest short term, and under high demand it's different. Otherwise I wouldn't mention it. So, if a new motor is behaving like the old one, why?

Only experience I had with a small clock motor was with an Electric Time black box motor. There was a clock on the old SS Pierce building in Brookline, MA that was running backwards. The old Howard timepiece was replaced with an Electric Time black box. It had a tiny synchronous motor with a circuit board attached. I think there was a blown diode. I should have saved it, but that was my mistake. It was at least 15 years ago, and I don't think it was worth the $350 I paid for it, but it was what was needed.

So, is the line frequency really 60 HZ or is it not.

The number of poles...I am neither am engineer nor an expert. Too bad it might cost $50 or more for a frequency meter to answer the question.

 

[eskmill son]

Yes. Over the long term. Web searches suggest short term, and under high demand it's different. Otherwise I wouldn't mention it. So, if a new motor is behaving like the old one, why?

Only experience I had with a small clock motor was with an Electric Time black box motor. There was a clock on the old SS Pierce building in Brookline, MA that was running backwards. The old Howard timepiece was replaced with an Electric Time black box. It had a tiny synchronous motor with a circuit board attached. I think there was a blown diode. I should have saved it, but that was my mistake. It was at least 15 years ago, and I don't think it was worth the $350 I paid for it, but it was what was needed.

So, is the line frequency really 60 HZ or is it not.

The number of poles...I am neither am engineer nor an expert. Too bad it might cost $50 or more for a frequency meter to answer the question.

I will certainly let you know once I get hold of one and measure it

 

[Molson3003]

need to know which direction the shaft rotates for the clock to run properly (clock wise or counter clock wise).

Put the new rotor back to the way you got it, power it up, and see which way the shaft rotates.

If it’s rotating in the proper direction, then something was altered by combining the two. If it still rotates in the reverse direction, then there is something fundamentally different between the two rotors. I would think two movements designed to be powered by such similar rotors would be driven in the same direction.

I can’t say for sure how to fix, but at least you’ll know what you have and are dealing with

 

[eskmill son]

need to know which direction the shaft rotates for the clock to run properly (clock wise or counter clock wise).

Put the new rotor back to the way you got it, power it up, and see which way the shaft rotates.

If it’s rotating in the proper direction, then something was altered by combining the two. If it still rotates in the reverse direction, then there is something fundamentally different between the two rotors. I would think two movements designed to be powered by such similar rotors would be driven in the same direction.

I can’t say for sure how to fix, but at least you’ll know what you have and are dealing with

The original motor (currently re-installed) runs in the proper clockwise direction. The seconds hand runs consistently 10 sec too fast.

The replacement motor ran consistently 10 sec fast as well, but counter clockwise. When I bought the second motor, it came with the old movement that I didn’t realize needs a counter clockwise rotation for the motor ‍ Photo below is replacement motor in its movement.

 

[Wimberleytech]

This is indeed a head scratcher.
I can say for certain, your problem is NOT the line frequency--I bank my career on it.

There is nothing I can imagine in the train wheels that would make the clock run FASTER...IF they are original and not modified.

When you say "10 seconds fast" can you say in what time frame (e.g., 10 seconds fast in a two minute time frame)?

Do you know the provenance of this clock? Has it been worked on before? Did someone try to fix it and find a motor that was incorrect?

 

[Wimberleytech]

Following up...I would like to know the rate measured as precisely as you can. Unplug the clock. Set the clock and second hand to, say, 12:00. Then plug it in at the same time you start a timer on you phone. Let it run several hours and then record the error.

 

[Molson3003]

Concerning the new rotor running backwards:

Search for this

Modern clock running backwards

Whatever direction the movement is designed to be driven, synchronous rotors can run in either direction. There are generally various methods to ensure that it runs in the desired direction.

In your situation, I’m guessing the shaded poles determine the direction of rotation

 

[Molson3003]

Now that I know you have two rotors and movements -

Do you have hands for this. I can assume no dial. Can you set the two up side by side?

You probably know where I’m going with this.

I believe the gaining issue is some wear in the original hands / movement

 

[davefr]

Concerning the new rotor running backwards:

Search for this

Modern clock running backwards

Whatever direction the movement is designed to be driven, synchronous rotors can run in either direction. There are generally various methods to ensure that it runs in the desired direction.

In your situation, I’m guessing the shaded poles determine the direction of rotation

I still say you're focus should be the movement/hands vs. the motors for running fast. Are you sure the movement itself isn't geared for 50 Hz? A gear train needs to run faster to compensate for a single spindle rotor that will run slower at 50 Hz. Yet if that rotor is already running faster at 60Hz the clock will gain time at 1.2X. (ie 12 seconds gain every 1 minute).

In the case of Telechron, the rotor's internal reduction gearing dictates the speed. But the Sangamo rotor has no reduction gearing so it has to be the clock movement's gearing that needs to be designed for the specific line frequency.

Are you sure it's the original movement for the clock and the tag that says 60Hz is for that movement. The weird shaped hole in that wood case doesn't look like something a clock company would do.

 

[Wimberleytech]

I still say you're focus should be the movement/hands vs. the motors for running fast. Are you sure the movement itself isn't geared for 50 Hz? A gear train needs to run faster to compensate for a single spindle rotor that will run slower at 50 Hz. Yet if that rotor is already running faster at 60Hz the clock will gain time at 1.2X. (ie 12 seconds gain every 1 minute).

In the case of Telechron, the rotor's internal reduction gearing dictates the speed. But the Sangamo rotor has no reduction gearing so it has to be the clock movement's gearing that needs to be designed for the specific line frequency.

But the OP said 20-30 seconds in five minutes. If it is a 50hz movement, that would mean 60 seconds in five minutes. Of course, he could have made an error when doing the measurement. That is why I asked him to do a very precise measurement--the result of which might support your argument (50 Hz movement with a 60 Hz line frequency). We need more data.

Looking back at the OP, the nameplate says 60 Hz.

 

[davefr]

But the OP said 20-30 seconds in five minutes. If it is a 50hz movement, that would mean 60 seconds in five minutes. Of course, he could have made an error when doing the measurement. That is why I asked him to do a very precise measurement--the result of which might support your argument (50 Hz movement with a 60 Hz line frequency). We need more data.

Looking back at the OP, the nameplate says 60 Hz.

I agree. If I were the OP I'd remove all the hands from the clock and clip an alligator clip on the stem for the second hand and synchronize it with a known good clock and look for any deviation over the course of a few minutes. In my experience almost all cases of electric clocks gaining time are related to problematic hands creating the illusion of gaining time.

 

[Molson3003]

“synchronize it with a known good clock and look for any deviation over the course of a few minutes. In my experience almost all cases of electric clocks gaining time are related to problematic hands creating the illusion of gaining time.”

Yes agreed. We know he now has two motors and movements. I suggested he set the two up side by side. The new one may not be “known good”, but if there is any deviation between them it will tell us something.

IMO davefr gave the answer to the original issue in the beginning of this thread

There are now two perceived issues. Probably would be wise to focus on one issue at a time to eliminate confusion

 

[TQ60]

We had heard "stories" from old retired folks that way beck in the pre interconnected grid days that a simple clock was used to check or monitor overall frequency.

Compared to wind up regulator the line frequency changes effect the time.

This may have a wrong motor installed at some point.

Find another electric clock and set to same time.

If both do same then line, if other stays good then clock.

A repair could have been made with similar gear or similar motor meaning correct or exact part not available but a close enough was handy.

Maybe look for parts that look different age or count teeth.

 

[hamlens1]

We had heard "stories" from old retired folks that way beck in the pre interconnected grid days that a simple clock was used to check or monitor overall frequency.

Compared to wind up regulator the line frequency changes effect the time.

This may have a wrong motor installed at some point.

Find another electric clock and set to same time.

If both do same then line, if other stays good then clock.

A repair could have been made with similar gear or similar motor meaning correct or exact part not available but a close enough was handy.

Maybe look for parts that look different age or count teeth.

We had heard "stories" from old retired folks that way beck in the pre interconnected grid days that a simple clock was used to check or monitor overall frequency.

Compared to wind up regulator the line frequency changes effect the time.

This may have a wrong motor installed at some point.

Find another electric clock and set to same time.

If both do same then line, if other stays good then clock.

A repair could have been made with similar gear or similar motor meaning correct or exact part not available but a close enough was handy.

Maybe look for parts that look different age or count teeth.

 

[hamlens1]

By way of causing confusion, let me give you my experience.
I inherited, in 1998, a Sessions electric chime, appears to be "Falsbury 2E circa 1939". That gives me about 20 years' experience with this clock, and having about 50 clocks/timers, I am fixated on all running and having the (approximate) correct time. This Sessions has worked well, except for major repair in 2010, where the motor was replaced with an exchange motor from Mike's Clock Clinic. When the power is interrupted to this clock (power failure or unplugging), it occasionally restarts at a faster speed, 10-15 seconds a minute. Since it has a second hand, it is easy to observe that it is running fast, and also easy to measure it against a watch. It usually restarts at correct speed with one unplug/plug. For what it's worth...

 

[hamlens1]

By way of causing confusion, let me give you my experience.
I inherited, in 1998, a Sessions electric chime, appears to be "Falsbury 2E circa 1939". That gives me about 20 years' experience with this clock, and having about 50 clocks/timers, I am fixated on all running and having the (approximate) correct time. This Sessions has worked well, except for major repair in 2010, where the motor was replaced with an exchange motor from Mike's Clock Clinic. When the power is interrupted to this clock (power failure or unplugging), it occasionally restarts at a faster speed, 10-15 seconds a minute. Since it has a second hand, it is easy to observe that it is running fast, and also easy to measure it against a watch. It usually restarts at correct speed with one unplug/plug. For what it's worth...

Correction - in my haste/confusion I transcribed the history of the wrong clock. I inherited the Sessions in 1980. It's had 3 repairs: 1980 repair chime motor coil, 1990 replace fiber gear, 2008 replace/exchange motor; and periodic cleanings. So running about 40 years with the odd speed habit.