Hi
I have an R31. It came with a dead battery. I bought a genuine IBM one from ebay and it works, but if you pull the lead out while it is charging it locks the laptop up.
Two of the lights under the screen - caps lock and the screen one - flash.
It does it in Ubuntu, but works fine in XP.
Any ideas?
Simon
On 06/01/11 13:36, Simon Royal wrote:
Hi
I have an R31. It came with a dead battery. I bought a genuine IBM one from ebay and it works, but if you pull the lead out while it is charging it locks the laptop up. Two of the lights under the screen - caps lock and the screen one - flash. It does it in Ubuntu, but works fine in XP. Any ideas?
I have the same problem with one of my laptops. If I remove the audio-out lead while it is switched on it crashes with two flashing lights. (Num lock and cap lock I think).
I suspect it is caused by a (static?) discharge as I have been able to measure a potential of about 150 volts between the two devices (laptop & TV set) although there is no current available to do any (much) damage.
I just fall back on the old hardware adage of "don't plug or unplug under power".
Nev
It does it under Ubuntu 10.10 but not under Ubuntu 9.10 or XP.
Sticking with the latter two at the mo, until I can work out why 10.10 does it.
Simon
On Sun, Jan 9, 2011 at 9:07 AM, nev young nev@nevilley.demon.co.uk wrote:
On 06/01/11 13:36, Simon Royal wrote:
Hi
I have an R31. It came with a dead battery. I bought a genuine IBM one from ebay and it works, but if you pull the lead out while it is charging it locks the laptop up. Two of the lights under the screen - caps lock and the screen one - flash. It does it in Ubuntu, but works fine in XP. Any ideas?
I have the same problem with one of my laptops.
If I remove the audio-out lead while it is switched on it crashes with two flashing lights. (Num lock and cap lock I think).
I suspect it is caused by a (static?) discharge as I have been able to measure a potential of about 150 volts between the two devices (laptop & TV set) although there is no current available to do any (much) damage.
I just fall back on the old hardware adage of "don't plug or unplug under power".
-- nev
main@lists.alug.org.uk http://www.alug.org.uk/ http://lists.alug.org.uk/mailman/listinfo/main Unsubscribe? See message headers or the web site above!
On 09/01/11 09:07, nev young wrote:
I suspect it is caused by a (static?) discharge as I have been able to measure a potential of about 150 volts between the two devices (laptop & TV set) although there is no current available to do any (much) damage.
I just fall back on the old hardware adage of "don't plug or unplug under power".
That isn't static, it sounds like a ground level mismatch between the two devices.
If your TV set has an earth pin connection then I would get the set PAT tested or have the earth bonding in whatever mains socket you have it plugged into checked out.
Laptops are a bit of a funny beast when it comes to Ground as they tend not to have a ground connection bonded to mains earth through the PSU so there is potential (lol) for a ground mismatch when compared against another item. But a 150v PD between the two would suggest to me that one of them is faulty or there is something very wrong with your mains wiring.
On 09/01/11 18:31, Wayne Stallwood wrote:
On 09/01/11 09:07, nev young wrote:
I suspect it is caused by a (static?) discharge as I have been able to measure a potential of about 150 volts between the two devices (laptop & TV set) although there is no current available to do any (much) damage.
I just fall back on the old hardware adage of "don't plug or unplug under power".
That isn't static, it sounds like a ground level mismatch between the two devices.
If your TV set has an earth pin connection then I would get the set PAT tested or have the earth bonding in whatever mains socket you have it plugged into checked out.
Laptops are a bit of a funny beast when it comes to Ground as they tend not to have a ground connection bonded to mains earth through the PSU so there is potential (lol) for a ground mismatch when compared against another item. But a 150v PD between the two would suggest to me that one of them is faulty or there is something very wrong with your mains wiring.
TVs do not have an earth connection. This is a standard for such devices and has been for over 40 years.
There should be no connection between earth and the output of a laptop power brick.
Many devices are not earthed by design. At least that was the case when I was an electrical engineer. Things may have changed since I became a software engineer.
The PD of about 150v is very high impedance, well over 100MΩ, and is quite normal for such devices. You need a *special* voltmeter to read it. It is not normally a problem as it leaks away eg. via moisture in the atmosphere, but sometimes it can bite you.
The reason for it being about 150v is it is (√2/2)*(peak mains volts).
On 10/01/11 08:40, nev young wrote:
TVs do not have an earth connection. This is a standard for such devices and has been for over 40 years.
Except the 2 LCD sets I have here, Both LG the NEC plasma I repaired for someone the other month and countless other units I have seen.
In fact if you look at the design of some of the lower end sets with the single tin can holding both the SMPSU and the inputs (some of which have exposed metal) then you would see that it actually would be a fair amount of effort to make them Class II.
Now if we were talking about CRT TV's which I made the assumption hardly anyone is still using...then yes it was very common for them not to have a earth connection because the nature of the most common method of powering the things (i.e shoving mains through a bridge rectifier which has it's negative side tied to Chassis) means that the chassis can sit at what looks roughly on most meters like half mains potential. In fact it is more like half wave AC at roughly -320volts. This is why if you are particularly well grounded you will feel a bite from the antenna socket of many CRT TV sets, all chassis grounded connections should be decoupled but naturally you often see some leakage current.
So if you were using a CRT set then maybe that is what you saw..but as an ex electrical engineer I would have expected you to know that wasn't static :)
There should be no connection between earth and the output of a laptop power brick.
Except the Dell PA-1650-05D I just randomly picked from the top of the spare adaptor pile which has a nice connection from the outer ring of the DC connector to the earth pin. Maybe I was just lucky there so let's try another one, this time a HP part number 393954-001. Yup the same :)
Many devices are not earthed by design. At least that was the case when I was an electrical engineer. Things may have changed since I became a software engineer.
Yes Correct. Class II devices (double insulated) do not require an earth connection and often are not earthed by design...not all devices are Class II
Wayne Stallwood wrote:
Now if we were talking about CRT TV's which I made the assumption hardly anyone is still using...then yes it was very common for them not to have a earth connection because the nature of the most common method of powering the things (i.e shoving mains through a bridge rectifier which has it's negative side tied to Chassis) means that the chassis can sit at what looks roughly on most meters like half mains potential. In fact it is more like half wave AC at roughly -320volts. This is why if you are particularly well grounded you will feel a bite from the antenna socket of many CRT TV sets
Aaaaah! Thanks for describing this, it's answered a long-standing puzzle filed away in the "back in the day" section of my brain. I had several shocks from the antenna socket of various CRT TVs, and having experienced mains shocks could tell that it wasn't static and that it did indeed feel like mains AC, but was always puzzled why this should be the case when the UHF socket in question was a) a supposedly un-powered inbound connection and b) something designed for a few microvolts @ a few hundred MHz. Know I know :-)
Cheers, Simon
-
nev young -
Simon Ransome -
Simon Royal -
Wayne Stallwood