Accutron not humming--components seem OK

[LittleWatchShop]

OK, I am on my fifth or sixth 218 service with great success.  Once you establish a methodology, these are relatively easy.

I am servicing a 218 D now and it will not hum

I have verified the following

-drive coils
-phasing coil
-resistors
-capacitor
-EB junction, CB junction (have not verified beta)

Kind of at a loss.  All connections seem to be fine.

Wondering if the watch was accidentally demagnetized???  Using a compass, I verified that the tuning fork does have some magnetic attraction.

Scratching my head.

[nickelsilver]

Do you have a good tuning fork you can try? I remember reading about someone who had figured out how to remagnetize them, but it was too complicated for me to do anything other than say, "wow!".

[LittleWatchShop]

18 minutes ago, nickelsilver said:

Do you have a good tuning fork you can try? I remember reading about someone who had figured out how to remagnetize them, but it was too complicated for me to do anything other than say, "wow!".

Yeah, that should be my next step.  Will report back.

Went back and ran measurements again.  Looks like I got a little confused.  One of the drive coils is bad.

I wondered if by measuring, I may have destroyed a coil.  The wire is only about 15um in diameter (about 0.6 mils).  After doing some research, I found this which indicates the fusing current at around 150mA.  A multimeter will not use that much current when measuring resistance.

[Zero]

On 2/2/2024 at 2:40 PM, LittleWatchShop said:

I wondered if by measuring, I may have destroyed a coil.  The wire is only about 15um in diameter (about 0.6 mils).  After doing some research, I found this which indicates the fusing current at around 150mA.  A multimeter will not use that much current when measuring resistance.

I believe multimeters use a constant current generator and it should not be that high. Maybe you accidentally used the multimeter's diode mode? That may inject more current.

[JohnR725]

2 hours ago, Zero said:

I believe multimeters use a constant current generator and it should not be that high. Maybe you accidentally used the multimeter's diode mode? That may inject more current.

The problem with the discussion is the individual who started the discussion probably has a vast assortment of multi meters possibly vintage ones and we don't actually know the specifications like how much voltage do they have. A lot of the early multi meters had considerably more voltage than you'd like to have been working on electric watch. But otherwise most the digital meters should be just Fine I use a cheap digital meter for quartz watches and tuning forks and as far as I know I've never had a problem with burning out a coil. Although you do want to be careful with your probes to keep them away from the wires as the wire probably does not like to be probed at all it would disintegrates. It is always best to test something that the wire Is connected to rather than getting anywhere near the wires themselves. This is where making your own custom probes with really sharp needlelike points works much better in other words much smaller diameter than the standard probes although you can use them it really is better to have smaller

 

[LittleWatchShop]

2 hours ago, JohnR725 said:

the individual

LOL

Yes my first VOM was a Triplett Model 630, 1970.  However, I am not a luddite...my best meter is a Fluke 87V.  I made the measurements with Cen Tech P35017.  This morning, I measured the current output of the CT with my Fluke.  When measuring resistance with the CT, I get 484uA.  When in diode mode, I get about 800uA.

I know you have lots of Accutron experiene...I take it you have never knowingly popped one of those coils via measuring??

---non sequitur---  the going train on these things continue to amaze me.  I was initially deathly afraid of it because of the index wheel.  No more.  About 20% of the time, the wheels just jump in place as soon as you drop the plate down.  The rest yield quickly with a few nudges with my modified oiler.  I only wish Bulova used similar engineering on their cases.

2 hours ago, JohnR725 said:

Although you do want to be careful with your probes to keep them away from the wires as the wire probably does not like to be probed at all it would disintegrates. It is always best to test something that the wire Is connected to rather than getting anywhere near the wires themselves.

Yes

[nickelsilver]

It's been a long time and I rarely work on quartz stuff, but had one for a friend I suspected a coil was bad, grabbed my trusty Radio Shack (Micronta) digital meter I bought as a teenager, thinking it should have a low enough output. From memory, you want less than 2v to be safe with quartz coils. I recall we had meters in school with a resistor across the leads to drop the voltage. Turns out the Micronta puts out 4v, which is common. Didn't have a resistor on hand, so didn't test (ended up not being the coil- but at least I didn't kill it!).

 

I don't know the difference in the coil wire diameter between common quartz and Accutron; my gut says the Accutron is a bit heavier, so probably doesn't mind the extra voltage?

[LittleWatchShop]

5 minutes ago, nickelsilver said:

I don't know the difference in the coil wire diameter between common quartz and Accutron; my gut says the Accutron is a bit heavier, so probably doesn't mind the extra voltage?

According to the patent at least, the Accutron wire is 0.6 mil which is about 15 microns.  I will try to find some info about the quartz coil wire.

I pulled a quartz coil and measured it with my JKA and got between 15 and 18 microns.  The JKA resolves 10um tic marks, so I am interpolating to get this number.

Thus, the quartz coil and Accutron coils have comparable wire diameters.  I never worried about measuring quartz coils, so I will no longer worry about measuring Accutron coils.

A further experiment might be to measure the fusing current for a quartz coil.  A test for another day!!

[JohnR725]

4 hours ago, LittleWatchShop said:

I take it you have never knowingly popped one of those coils via measuring

Not that I'm ever aware of. The problem is with measuring the coils is everybody's specifies a resistance and if the meters were as dangerous as were thinking they are then we must have way more destroyed coils from the meters Then we appear to be having so the meters probably not the problem.

4 hours ago, nickelsilver said:

From memory, you want less than 2v to be safe with quartz coils.

One of those pesky decimal point problems again? The concern when measuring a quartz  coil or any coil associated with electronic circuitry is having enough voltage to turn the circuit on and causing a false reading. So ideally I think the number is 0.2 V because anything above that you could risk turning something on and have a problem. But the problem was only typically of having a false reading not of vaporizing your coil.

 

 

 

 

[nevenbekriev]

Guys, what is the discussion for? Is it possible to damage watch coil with normal multimeter supplied with 9V or 3V batteries??? This is a nonsence, stupid thought. Of coutse not possible.

[JohnR725]

 

1 minute ago, nevenbekriev said:

Guys, what is the discussion for? Is it possible to damage watch coil with normal multimeter supplied with 9V or 3V batteries??? This is a nonsence, stupid thought. Of coutse not possible.

Well the title indicates somebody's having a problem with tuning fork watch. Then there was the problem of a coil that was functional and now it isn't which is probably why we were discussing measuring coils. Then

10 hours ago, Zero said:

I believe multimeters use a constant current generator and it should not be that high. Maybe you accidentally used the multimeter's diode mode? That may inject more current.

We have this comment which is interesting.  Mainly because it's not what the problem is I was under the impression that the diode voltage checking up the voltage to a high enough level to turn the diode on where ideally when measuring resistance the voltage should be low enough not to turn things on. But?

5 hours ago, LittleWatchShop said:

Yes my first VOM was a Triplett Model 630, 1970

Then I was just poking fun at somebody I thought maybe had a collection of meters possibly a vacuum tube voltmeter. A lot of times in watch repair not usually electric watch repair but in mechanical watch repair there are a lot of people who embrace vintage tools and don't want to move on to modern newfangled technology.  Depending upon where you are in the universe mention the word CNC for instance and they give a really amusing as there are people that consider that devil worshiping in watch repair or computers.

Though then this is the interesting link I wonder if the exact same circuitry?

https://www.triplett.com/products/3030-model-630-analog-multimeter-with-chemical-resistant-glass-meter-window

 

 

 

[LittleWatchShop]

10 minutes ago, JohnR725 said:

Though then this is the interesting link I wonder if the exact same circuitry?

https://www.triplett.com/products/3030-model-630-analog-multimeter-with-chemical-resistant-glass-meter-window

Well, who knows.  Looks identical.  Uses the 30V battery just like mine.  I bet it is the same.

[nevenbekriev]

OK, almost all old and modern ADC based multimeters are not able to output more than 2.5V on the probes, and the voltage that will destroy the coil is far far beyond. The old system multimeters also will not output more than they are supplied with, and it is usually 1.5 0r 3 volts. Only megaohmmeters will output more than 30 V, but no reason one to use such device

[JohnR725]

16 minutes ago, LittleWatchShop said:

Well, who knows.  Looks identical.  Uses the 30V battery just like mine.  I bet it is the same.

This works out good for us we get a user's manual. So it looks like for the desired effect you want to use it at the highest resistance measurement range as that will give you the best voltage for destruction. Otherwise it still outputting too much voltage even at the lower voltage unless you just measuring the coil without the circuitry. On the other hand you not use this meter anymore so that's not a problem at all anyway but just in case it's lurking around Somewhere in the shop and you decide to use it you probably shouldn't.  

 

 

Model 630 3030-1.pdf

[RichardHarris123]

Isn't it the amps, rather than volts, that cause heat and destroy the coil? 

[Neverenoughwatches]

7 minutes ago, RichardHarris123 said:

Isn't it the amps, rather than volts, that cause heat and destroy the coil? 

Not that know I much about electronics I understood it the same, its not the voltage that can kill you its the amount of current flow .

[Zero]

6 hours ago, LittleWatchShop said:

I made the measurements with Cen Tech P35017.  This morning, I measured the current output of the CT with my Fluke.  When measuring resistance with the CT, I get 484uA.  When in diode mode, I get about 800uA.

@LittleWatchShop Was the failed coil D1 (cell coil) or D2 (component side coil), and was the measurement done in-circuit with the battery installed?

 

4 minutes ago, RichardHarris123 said:

Isn't it the amps, rather than volts, that cause heat and destroy the coil? 

Yes. Even a 1.5V button battery can burn a tiny coil, if it can drive a high current for long enough.

[LittleWatchShop]

1 minute ago, Zero said:

Was the failed coil D1 (cell coil) or D2 (component side coil), and was the measurement done in-circuit with the battery installed?

Too much water under the bridge...I dont remember (I am old).

 

2 minutes ago, Zero said:

Yes. Even a 1.5V button battery can burn a tiny coil, if it can drive a high current for long enough.

Pretty much ohms law.  It is the current that matters and if there is enough voltage for a given resistance, then you will have enough current to do the deed.  In this case, if the data I presented is accurate, a 1.5 volt battery can provide 150mA into a 10 ohm resistor...far lower than any coil resistance.

 

1 hour ago, JohnR725 said:

Model 630 3030-1.pdf

Yeah, now I am pissed.  This thread has lead me off onto a bunny trail of ancient equipment I own.  I got my meter out (took me awhile to find it) and I opened it up.  Then I remembered that long long ago, I replaced a couple of the resistors for a reason I cannot remember.  Now, I want to replace those resistors with the correct 1% resistors.  BUT, I cannot find the correct manual for my model.  Somewhere in this house, I have my own manual...ugh.

 

[JohnR725]

2 hours ago, nevenbekriev said:

Guys, what is the discussion for?

In the old days this group was a group discussing watch repair. The current group is exactly for this hijacking the subjects and going off in new directions.

8 minutes ago, LittleWatchShop said:

This thread has lead me off onto a bunny trail of ancient equipment I own.

So proof hijacking the discussion and going in a new direction because that's the direction the group wants to go in.

 

10 minutes ago, LittleWatchShop said:

I got my meter out (took me awhile to find it) and I opened it up. 

Hopefully when you opened it up everything was fine and you found no bad reasons I. I was having a discussion with a friend where the older batteries not the vintage but the older batteries seem to be much better at not leaking versus the modern batteries that seemed to like to disintegrate and leak all over the place. So I now extremely careful with any of my test equipment or anything that uses batteries to try to remember to remove the batteries to prevent upcoming disasters.

12 minutes ago, LittleWatchShop said:

Pretty much ohms law.  It is the current that matters and if there is enough voltage for a given resistance, then you will have enough current to do the deed.  In this case, if the data I presented is accurate, a 1.5 volt battery can provide 150mA into a 10 ohm resistor...far lower than any coil resistance.

About ohms law I'm a little bit confused here?

27 minutes ago, Zero said:

Yes. Even a 1.5V button battery can burn a tiny coil, if it can drive a high current for long enough.

So here's my confusion suppose we build a power supply and it's to simulate a special watch battery with infinite current. Typically a watch battery open circuit voltage brand-new is almost 1.6 V. That's our power supply let's make it 100 A we have enough current the fry just about anything. But the coil has a resistance typically in a quartz watch around 1800 ohms. So I believed to figure out the current you would take the voltage and divide in the resistance and get the current? So how could you increase the drive current?  Then yes technically it's a coil and that does screw up things a little bit  because initially when you hook it up because of its inductive properties but that's not going to change this discussion of. In other words is not going to draw very much current and the typical watch battery could drive it forever and it shouldn't have an issue. Intensity a much bigger issue for a circuit driving it because that pesky inductive problem of the building up magnetic field in the collapsing field that's where things get interesting for electronic drive circuitry.

1 hour ago, Neverenoughwatches said:

Not that know I much about electronics I understood it the same, its not the voltage that can kill you its the amount of current flow

Sad I'm hopelessly confused here. I tend to be much more afraid of voltage especially high voltage. I do not have fond memories of things with high voltages. Think about it this way I don't think I've ever had any pain from holding a watch battery but high voltages where things that you perceive could be an insulation don't exactly function that way.  What are basically managing to get your hand anywhere near something that's high-voltage is not a pleasant experience. Then yes the current is important but it really helps if you can get the current to flow with a little high-voltage

[RichardHarris123]

TASER's are high voltage, low current, if they weren't, they would kill you. 

[LittleWatchShop]

30 minutes ago, JohnR725 said:

Then yes the current is important but it really helps if you can get the current to flow with a little high-voltage

Ohms law again.  It is the current that kills, but your body is a resistor.  Here.

[Zero]

40 minutes ago, LittleWatchShop said:

Too much water under the bridge...I dont remember (I am old).

The reason I ask is because it is possible to short the battery +ve terminal and complete the circuit (see red lines in the diagram below, sorry for the low resolution).

So if a multimeter probe touches two pins simultaneously, you can complete the circuit. The NPN switch pins are very close to each other, only a single probe or tweezer is needed for this. There doesn't seem to be any protection diodes to prevent this.

 

47 minutes ago, LittleWatchShop said:

Yeah, now I am pissed.  This thread has lead me off onto a bunny trail of ancient equipment I own.

Your equipment is probably just fine . The old stuff is better than most of the new stuff we can buy nowadays, they were built to last.

[LittleWatchShop]

1 minute ago, Zero said:

it is possible to short the battery

Yes, indeed. I made sure that the battery was out of the circuit during tests...for the reasons you stated!!

[Neverenoughwatches]

39 minutes ago, RichardHarris123 said:

TASER's are high voltage, low current, if they weren't, they would kill you. 

In my younger days tinkering with cars i had plenty of belts from petrol engine ignition systems running at tens of thousands of volts.

[nevenbekriev]

6 hours ago, Zero said:

The reason I ask is because it is possible to short the battery +ve terminal and complete the circuit (see red lines in the diagram below, sorry for the low resolution).

So if a multimeter probe touches two pins simultaneously, you can complete the circuit. The NPN switch pins are very close to each other, only a single probe or tweezer is needed for this. There doesn't seem to be any protection diodes to prevent this.

 

 

The short connections that You describe are possible, but it is not dangerous for the coils and even for the entire ciruit. The resistance of the coils is big, so the  battery voltage can not produce enough current to destroy anything. No normal multimeter can do any harm too.