Folks,
Got a Dell Vostro 200 mini tower with XP on there that seems to be a bit off in the realtime clock lately. Around five years old so needs a new
3V coin cell on the mobo.In order not to lose all the setup stuff, can those CR2032 coin cells be hot-swapped while the PC is running?
Of course using ESD straps, being careful and all that.
-- Regards, Joerg http://www.analogconsultants.com/
the BIOS flash update utility has a backup feature which keeps settings as well. you back it up, swap the battery, and then re-apply the backed up flash image.
And yes, you CAN apply an external 3V source to the MOBO. Just remember that you will be fighting the very low internal resistance of a dead battery for the few seconds you are under power as you remove it, and for the few seconds you re under external power as you install the new one. Be very careful about polarity, and do not exceed 3 volts so you do not begin "feeding" the battery.
As a side note, many modern motherboards have enough capacitance at that sub-circuit location to retain things long enough for you to swap the battery. I do not know if yours is such a design.
another side note is that RTCs in PCs are not very accurate with the original Pc deign and crystal. Newwer designs may use more accurate clock sources, but most do not, and your most accurate clock possible is your cell phone, or iPad or other cell system connected or GPS enabled device. Always bet to keep your PC's clock referenced to such a more accurate source.
Internet updates are prone to latency errors , so do not expect better than plus or minus about 1.5 seconds in that realm.
The phone or GPS device is the clear winner, and a good modern wrist watch usually tracks those pretty well once set. Usually within mere seconds per year. The phones are ALWAYS accurate as they are ALWAYS constantly updated.
I've done it. The backup function of the battery means the circuitry only draws battery power while power is OFF (and I do mean OFF, 'standby' of ATX power supplies is an ON state, even though the computer seems powered down).
There's also a hold capacitor, usually a few seconds of power is assured while swapping the coin cell.
Thanks. Now I've got to find that sort of utility, somewhere.
If I had a flash update utlity :-)
So I assume even with a running PC one would still have to hook up a 3V supply in order not to lose data?
No clue, I think it's a Foxconn G33M mobo in there.
Actually, without web updates the RTC in this PC was remarkably accurate for all those years. Well, until yesterday. I rarely had to set it.
-- Regards, Joerg http://www.analogconsultants.com/
So maybe I should just hot-swap then.
That's odd. Because the PC here is always sent to hibernate and the power is turned off. But it remains connected to 120VAC. Still, this morning the RTC was off again by more than five minutes from yesterday.
And then the coin cell slips and our dog carries in to the kitchen, "Look, ma, I found bling-bling!" :-)
-- Regards, Joerg http://www.analogconsultants.com/
Yes, I do it all the time. Two methods:
There are a few CMOS backup and write utilities scattered around the web. I've had no success with these and don't use them. Check the dates as many are ancient.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Done, new battery is in. Did a power-down into hibernate, came back up like usual. The old battery still measures 3.272V but when loading it with as light a load as 10k it collapses to 2.5V. With 1k it goes to
1.6V. So I guess the old battery was truly exhausted. It was made by "Newsun" in Japan, never hear of that brand.While I had the PC open I saw that I have quite a build-up of dog hair in there, got to take it apart and clean it. Our big lab likes to curl up down there when I am doing SPICE runs and warm air comes out. It's amazing how tight of a space they can snuggle themselves into.
Supposedly there is a Dell tool but I haven't found it yet.
Thanks for the help, Jeff.
-- Regards, Joerg http://www.analogconsultants.com/
Oops. That should the positive terminal connector thing.
It's dead. I get about 5 years out of such batteries.
I just tested a new 2032 battery. 3.28V with no load. 3.18V with a
10K load. I couldn't find a 1K resistor.Yeah, number crunching does make the machine run warm. Suggestions:
I searched but couldn't find anything. There are plenty of tools to save the BIOS image (usually as part of a BIOS upgrade), but nothing I could find that saves the settings.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
[...]
It ain't the same. In his opinion :-)
Unfortunately on the Dells the intake is on the left side and that's exactly where the Labrador snuggles up. Raising the PC would not help but make it more prone to keeling over. For example when he hears the Fedex truck and tries to travel from underneath the PC table to the front door in milliseconds.
:-)
What makes it sweat is when you are almost done with a switcher and then have to enter real xfmr coupling of 0.97 and such. Important to gauge the dissipation in snubber parts. That really taxes a PC.
I guess then the digital camera is the only option. Or paper and pen :-)
-- Regards, Joerg http://www.analogconsultants.com/
Joerg Inscribed thus:
Don't mess about ! Do it live. Use an anti static strap. Take care not to damage the cell holder while removing the old battery and don't let it flip out onto the circuit board. Make sure that you put the new battery in the right way up, positive uppermost.
It should not take more than a few seconds to do the swap.
PS. A wood or plastic toothpic might help depending on the holder type.
HTH.
--
Best Regards:
Baron.
Joerg Inscribed thus:
A tip that might be usefull... A yellow led with the leads sprung across the battery will give an instant indication of the battery state.
--
Best Regards:
Baron.
Well, it's already done. So not I am wondering about the laptops. They've got to have such batteries as well. Maybe time to check those out.
-- Regards, Joerg http://www.analogconsultants.com/
Laptops do not have button cell holders. They have wire leads spot welded or soldered to the button battery, a short pair of wires, and a tiny connector. The battery is insulated in shrink tube. The ritual is the same if you want to preserve the settings. Leave the power applied to the laptop and the laptop running. Unplug the old battery and quickly insert the new battery. Most such batteries are easily accessible through a door on the bottom of the laptop, although there are a few abominations where the manufacturer elected to hide the battery in difficult to find location.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
yeah. but be careful if you drop it it could short something out,
-- ?? 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
The BIOS flash is not the config CMOS NVRAM
dead battery is about 50 ohms and 2.7 volts
NTP is much better than that.
-- ?? 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
RTC's are often rather crappy.
I use Socketwatch from...
I'm currently within 50ms of UTC/ ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
That's $10. I use Time synchronizer from Softnik Technologies. Better yet, it's free.
Sounds like that synchronizer is functional only at boot or manually...
"A simple time synchronizer that may be configured to startup at Windows boot, automatically connect to an atomic clock based time server, synchronize the system clock and then quit."
My machines run 24/7. My Socketwatch set-up automatically synchronizes every 60 minutes (you can set it to any interval you want).
Socketwatch also has a convenient tool to synchronize your watch to the second... count down and "beep-beep-beep-BOING" like the old time signals on your AM radio. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Why does the change have to be quick? Isn't the circuit powered as long as the laptop is? Because then one could solder in a new battery and re-use the connector instead of shelling out lots of dough for a specialty battery plus shipping charges.
Hey, it's nice, this morning the PC showed the correct time again :-)
What I really don't understand why in this day and age they don't write the settings into flash. I mean, we even successfully do that on totally cheapo uC design.
-- Regards, Joerg http://www.analogconsultants.com/
In the dark ages of laptops, the clock and CMOS memory were powered by the main battery with the button cell as a diode isolated backup. The button cell would draw no current until the main battery was either removed or depleted. Somewhere about 10 years ago, the clock chips and CMOS (serial) memory started drawing less power than the self leakage on the button cell. So, it was decided to just run them on the CMOS battery and not involve the main battery. I found this out the hard way by unplugging the battery with the computer running, and losing both the clock and CMOS settings. There's usually an electrolytic capacitor across the battery to deal with battery changes. I don't know how long it is expected to last, but it's probably measured in seconds.
I'm not 100% sure of the above, but I can check when I get to the office tomorrow, where I have some laptop schematics.
If your soldering iron is grounded and your charger grounds the laptop case, you'll probably short the battery terminals as soon as you hit it with the soldering iron tip. Also, replacement batteries are something like $3 to $8/ea, which is not a big deal. If you must roll your own, you can salvage a battery connector and cable from a dead laptop at the local recycler, and use that with a new battery.
Every time your PC loses an interrupt, the clock drops 15.6 msec. That's because most I/O devices have priority over the timer ticks. If you're doing lots of disk bashing or playing a DVD movie, you're going to see the clock slow down. How much depends on how many interrupts are lost.
Drivel: Many years ago, I decided that I wanted GPS accuracy on my office Unix server. I took the NEMA 183 output from an old Garmin 65 GPS, parsed the data with a shell script, and reset the PC clock according to the GPS time. What I forgot to include was a sanity check on the data. When the receiver lost sync, the GPS would produce
00:00:00 etc as the current time. It took a while to clean up my log files and recover from that mistake. This is another reason why I don't do much programming.Here's what's stored in the CMOS: Note that the first few bytes are the RTC current time and date (but not the TZ time zone). This info gets written to the CMOS chip once every second. If that were flash memory with an optimistic 100,000 write/erase cycles, the flash chip would be dead in several days.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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