Non Boaty .. computer clock

[VicS]

Recently I have noticed the clock, which is supposed to be automatically synchronised with an internet time server has some days been several hours slow.

I have usually re-synchronized it manually although some times I have had a message to say its been unsuccessful despite it actually having been corrected.

This morning I could not do it manually and had to actually set the clock myself.
This afternoon it's slow again but I have been able to get it to synchronize with the internet OK.

Any ideas what going on/ gone wrong ?

 

[sailorman]

internal battery ???

 

[prv]

internal battery ???

My first thought was "don't be silly, it's the synch with the Internet time server that's gone wrong, not the internal clock". But then it occurred to me that (at least on Unix) NTP won't synch automatically if the error is very large, to avoid surprising jumps in time in log files and the like. Assuming Windows is similar, you may well be right and it could be the battery, meaning that when the machine's turned on it's too far out of whack for an automatic synch.

I guess one way to test would be to shutdown with correct time set, leave for some suitable period, then disconnect the network before starting up again. If it comes up with wrong time, which can't be due to the Internet synch as there's no network, then it must be the internal clock and most likely the battery.

Pete

 

[theoldsalt]

I agree, usually CMOS battery on the motherboard. The battery will probably be a CR2032.

Help on replacing here :-

http://www.computerhope.com/issues/ch000239.htm

 

[ostell]

Available here: http://www.tlc-direct.co.uk/Products/PBCR2032.html

If the computer clock is losing time or date then it will be the battery.

On the computer I was working on yesterday the battery just unclipped using the plastic cap of a BIC pen. Don't take the battery out and leave it out while you get a new one.

Beware the shops that charge the earth for these batteries

 

[Lakesailor]

Could I suggest it may be the battery?

 

[budgester]

if it's windows change the internet clock it's looking up.

See

http://www.pool.ntp.org/en/use.html

For how to set up a new time server.

 

[VicS]

The puzzling thing is that some days it is correct and then suddenly I find it's about 3 hours slow.

Funny that this afternoon it was wrong when i had manually set it this morning. The machine was on all the day so I guess I did not set it properly.
Still Ok this evening.

Its next due to synchronize on 30 August so must watch carefully between then and now.

Thnx

 

[ostell]

The computer that had the clock problem (and others) was only about 7 months old. Took the battery out and cleaned the contact surfaces and it now seems to be holding the time correctly.

 

[VicS]

The computer that had the clock problem (and others) was only about 7 months old. Took the battery out and cleaned the contact surfaces and it now seems to be holding the time correctly.

Mine is nearer 7 years old.

I have discovered I have a CR 2032 if that's what's required. Sent in error by Maplin

 

[2nd_apprentice]

Have you tried using a different time server?

 

[VicS]

Have you tried using a different time server?

Yes one of the first things i tried

 

[ostell]

Mine is nearer 7 years old.

I have discovered I have a CR 2032 if that's what's required. Sent in error by Maplin

The battery can vary though the CR2032 seems to be the most common. It's obvious when you take the side off the computer. Use a piece of plastic to move the little catch on the rim of the battery to one side and lever the battery out (Bic pen top seems to be the right size).

I reckon that 7 years is about the usual life of the battery, depends on useage. (Now wait for responses telling me how long their battery has lasted)

 

[VicS]

Clock was correct when I switched off late yesterday evening.

Switched on this morning, without the router thing. Clock approx 1¾ hours slow.

Switched router on and synchronised it with the internet time OK


Get the tools out later and have a search for the battery.

 

[ostell]

Clock was correct when I switched off late yesterday evening.

Switched on this morning, without the router thing. Clock approx 1¾ hours slow.

Switched router on and synchronised it with the internet time OK


Get the tools out later and have a search for the battery.

That's the right symptoms. While you have the computer on the power supply is providing the voltage for the clock (and CMOS settings). It's when you switch off that it relies on the battery to keep the settings. Be as quick as you reasonably can to change the battery. Take care not to catch the circuit board!

The battery, if it is the button cell, is usually easy to spot.

Before you open the case remove the mains lead and press the on/off button. This will discharge the 5V sitting in those huge capacitors. Shorting out 5V can be a bit messy.

 

[lustyd]

While you have the computer on the power supply is providing the voltage for the clock (and CMOS settings).

The RTC isn't used at all when the computer is on, the time is updated using processor interrupts so the power to the clock is irrelevant.

For the time server, I recommend uk.pool.ntp.org if you're in the UK. Never use pool.ntp.org as this can cause you to use international servers which will be slightly less accurate (although only by a tiny bit).

Ideally, if this is a nav computer, you should be using GPS for your time sync and not internet time, but that's more complex to explain.

 

[laika]

Now getting a bit boatier

Ideally, if this is a nav computer, you should be using GPS for your time sync and not internet time, but that's more complex to explain.

Assuming you don't mean just using nmea data, is there an easier solution than finding a receiver which outputs a pps signal, chucking that into your serial port with some homebrew hardware then combing it with the nmea (or other) time of day data in software as a timesource? If not, isn't that a little esoteric for the average non-timenerd?

 

[lustyd]

Assuming you don't mean just using nmea data, is there an easier solution than finding a receiver which outputs a pps signal, chucking that into your serial port with some homebrew hardware then combing it with the nmea (or other) time of day data in software as a timesource? If not, isn't that a little esoteric for the average non-timenerd?

Yes it's a lot of effort, hence the wording Sadly I am a time nerd but usually on large server estates where cost and effort are not always the primary concern!

 

[laika]

Getting slightly less boaty again

Yes it's a lot of effort, hence the wording Sadly I am a time nerd but usually on large server estates where cost and effort are not always the primary concern!

Yes but now I'm concerned about being the only kid in the marina without sub-millisecond accuracy, especially after just googling this.

I'm suspecting for work you just *buy* the network timeclocks

 

[nimbusgb]

Ideally, if this is a nav computer, you should be using GPS for your time sync and not internet time, but that's more complex to explain.

Umm, why? The gps is doing the navigation not the pc. If the pc syncs to the nmea stream a second or two one way or the next makes no difference to anything! The clock on the pc will only drift a few microseconds in the time it takes to do any speed or other calcs.