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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Hot swapping CMOS batteries
The standard instructions for changing out a desktop CMOS battery say you
should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. On a related question, I also have an old Toshiba Satellite L35 laptop that I'd like to replace the CMOS battery on. It looks like I would have to take the entire laptop apart so I can remove the motherboard, turn it over, and replace the battery. Or, it turns out I can see the battery through the side of the wireless compartment, and I should be able the cut a window in the bottom of the case through which I could switch out the battery, then hot- glue the window back in place. Is there any reason not to do it that way? It's a lot more likely the laptop would survive the latter procedure. |
#2
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Hot swapping CMOS batteries
On 11/01/2017 05:42, Peabody wrote:
The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. On a related question, I also have an old Toshiba Satellite L35 laptop that I'd like to replace the CMOS battery on. It looks like I would have to take the entire laptop apart so I can remove the motherboard, turn it over, and replace the battery. Or, it turns out I can see the battery through the side of the wireless compartment, and I should be able the cut a window in the bottom of the case through which I could switch out the battery, then hot- glue the window back in place. Is there any reason not to do it that way? It's a lot more likely the laptop would survive the latter procedure. Yes, I added a tag to the battery line, so I could easily swap the battery , while jumpering in an external battery supply with a bit of a dropper resistor |
#3
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Hot swapping CMOS batteries
On 1/10/2017 9:42 PM, Peabody wrote:
The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. On a related question, I also have an old Toshiba Satellite L35 laptop that I'd like to replace the CMOS battery on. It looks like I would have to take the entire laptop apart so I can remove the motherboard, turn it over, and replace the battery. Or, it turns out I can see the battery through the side of the wireless compartment, and I should be able the cut a window in the bottom of the case through which I could switch out the battery, then hot- glue the window back in place. Is there any reason not to do it that way? It's a lot more likely the laptop would survive the latter procedure. Problem with doing anything with the power on is the unexpected. Suggest you at least put some tape on the battery so you have something to hold onto while you try to pry it out. The other issue is the reset. Assuming you have a reason/symptom to change the battery, it may be that the state of the memory is compromised. I've had laptops with rechargeable CMOS batteries that wouldn't run after I manually recharged them. Removing/waiting/replacing the charged battery fixed it. |
#4
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Hot swapping CMOS batteries
"Peabody" wrote in message ... The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. There doesn't seem to be any logic to hot swapping a CMOS battery - many motherboards have a jumper header to discharge the smoothing caps on the RTC rail - it holds for at least a few minutes with the battery out. Usually you don't even know it needs replacing till boot up reports a CMOS checksum error - then I just fit a new battery and load optimum defaults. There's only a couple of values I need to set manually. |
#5
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Hot swapping CMOS batteries
On 11/01/2017 20:14, Benderthe.evilrobot wrote:
"Peabody" wrote in message ... The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. There doesn't seem to be any logic to hot swapping a CMOS battery - many motherboards have a jumper header to discharge the smoothing caps on the RTC rail - it holds for at least a few minutes with the battery out. Usually you don't even know it needs replacing till boot up reports a CMOS checksum error - then I just fit a new battery and load optimum defaults. There's only a couple of values I need to set manually. The clue for me , is progressively worsening internal clock timekeeping. Incidently , hot soldering a tag, remove the power from the soldering iron before soldering , while still hot |
#6
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Hot swapping CMOS batteries
On 2017/01/11 12:56 PM, N_Cook wrote:
On 11/01/2017 20:14, Benderthe.evilrobot wrote: "Peabody" wrote in message ... The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. There doesn't seem to be any logic to hot swapping a CMOS battery - many motherboards have a jumper header to discharge the smoothing caps on the RTC rail - it holds for at least a few minutes with the battery out. Usually you don't even know it needs replacing till boot up reports a CMOS checksum error - then I just fit a new battery and load optimum defaults. There's only a couple of values I need to set manually. The clue for me , is progressively worsening internal clock timekeeping. Incidently , hot soldering a tag, remove the power from the soldering iron before soldering , while still hot Propane soldering irons work very well for this sort of thing - ungrounded... John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
#7
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Hot swapping CMOS batteries
On Wed, 11 Jan 2017, John Robertson wrote:
On 2017/01/11 12:56 PM, N_Cook wrote: On 11/01/2017 20:14, Benderthe.evilrobot wrote: "Peabody" wrote in message ... The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. There doesn't seem to be any logic to hot swapping a CMOS battery - many motherboards have a jumper header to discharge the smoothing caps on the RTC rail - it holds for at least a few minutes with the battery out. Usually you don't even know it needs replacing till boot up reports a CMOS checksum error - then I just fit a new battery and load optimum defaults. There's only a couple of values I need to set manually. The clue for me , is progressively worsening internal clock timekeeping. Incidently , hot soldering a tag, remove the power from the soldering iron before soldering , while still hot Propane soldering irons work very well for this sort of thing - ungrounded... Wasn't that one reason for promoting the cordless soldering iron sold in the seventies? I forget who made it, Radio Shack sold it under their name also, but there was something about an "iso-tip". Since it didn't plug in, you could use it where other irons might not be safe. Michael |
#8
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Hot swapping CMOS batteries
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#9
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Hot swapping CMOS batteries
"N_Cook" wrote in message news On 11/01/2017 20:14, Benderthe.evilrobot wrote: "Peabody" wrote in message ... The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. There doesn't seem to be any logic to hot swapping a CMOS battery - many motherboards have a jumper header to discharge the smoothing caps on the RTC rail - it holds for at least a few minutes with the battery out. Usually you don't even know it needs replacing till boot up reports a CMOS checksum error - then I just fit a new battery and load optimum defaults. There's only a couple of values I need to set manually. The clue for me , is progressively worsening internal clock timekeeping. Incidently , hot soldering a tag, remove the power from the soldering iron before soldering , while still hot IME: The time and date data usually survives - but it surprises me every once in a while. |
#10
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Hot swapping CMOS batteries
"John Robertson" wrote in message ... On 2017/01/11 12:56 PM, N_Cook wrote: On 11/01/2017 20:14, Benderthe.evilrobot wrote: "Peabody" wrote in message ... The standard instructions for changing out a desktop CMOS battery say you should turn everything off and unplug the power cord. But I wonder if guys who do this kind of stuff for a living don't hot swap the batteries with the power on, or at least leave the power cord plugged in so the always-on 5V supply provide power to the CMOS. That should prevent losing the contents of the CMOS memory, including the TOD and the BIOS settings. There doesn't seem to be any logic to hot swapping a CMOS battery - many motherboards have a jumper header to discharge the smoothing caps on the RTC rail - it holds for at least a few minutes with the battery out. Usually you don't even know it needs replacing till boot up reports a CMOS checksum error - then I just fit a new battery and load optimum defaults. There's only a couple of values I need to set manually. The clue for me , is progressively worsening internal clock timekeeping. Incidently , hot soldering a tag, remove the power from the soldering iron before soldering , while still hot Propane soldering irons work very well for this sort of thing - ungrounded... Even so - I wouldn't bother hot swapping a soldered in CMOS battery. |
#11
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Hot swapping CMOS batteries
Michael Black wrote:
Wasn't that one reason for promoting the cordless soldering iron sold in the seventies? I forget who made it, Radio Shack sold it under their name also, but there was something about an "iso-tip". Since it didn't plug in, you could use it where other irons might not be safe. Wahl made, and still makes them. -- Never **** off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-) |
#12
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Hot swapping CMOS batteries
On Sat, 14 Jan 2017, Michael A. Terrell wrote:
Michael Black wrote: Wasn't that one reason for promoting the cordless soldering iron sold in the seventies? I forget who made it, Radio Shack sold it under their name also, but there was something about an "iso-tip". Since it didn't plug in, you could use it where other irons might not be safe. Wahl made, and still makes them. Thanks. I suddenly couldn't remember who made it. Michael |
#13
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Hot swapping CMOS batteries
Michael Black wrote:
On Sat, 14 Jan 2017, Michael A. Terrell wrote: Michael Black wrote: Wasn't that one reason for promoting the cordless soldering iron sold in the seventies? I forget who made it, Radio Shack sold it under their name also, but there was something about an "iso-tip". Since it didn't plug in, you could use it where other irons might not be safe. Wahl made, and still makes them. Thanks. I suddenly couldn't remember who made it. You're welcome. -- Never **** off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-) |
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