My wife's 700m laptop backlight will light up when first turned on, but
then shuts down after 30-200 seconds. An external display works fine.
I assumed this was an inverter problem and bought a new one. I replaced
it today, but the problem remains. And yes, all the connectors seem to
be solid.
After some research, others have suggested the lid-closure switch could
be the culprit, but this switch seems to be working just fine. I can
boot to the bios and see the backlight come on and off as I activate the
switch (this assumes I do it within the 30-200 seconds that it works.)
Two questions:
1. Can a bad backlight tube cause this problem? It seems to work
fine, and has normal brightness when it works. Could it be taking too
much current which makes the inverter stop working? Could it require
more voltage once it warms up? Any chance that replacing the tube will help?
John Vallelunga wrote:
> My wife's 700m laptop backlight will light up when first turned on, but
> then shuts down after 30-200 seconds. An external display works fine.
> I assumed this was an inverter problem and bought a new one. I replaced
> it today, but the problem remains. And yes, all the connectors seem to
> be solid.
>
> After some research, others have suggested the lid-closure switch could
> be the culprit, but this switch seems to be working just fine. I can
> boot to the bios and see the backlight come on and off as I activate the
> switch (this assumes I do it within the 30-200 seconds that it works.)
>
> Two questions:
> 1. Can a bad backlight tube cause this problem? It seems to work
> fine, and has normal brightness when it works. Could it be taking too
> much current which makes the inverter stop working? Could it require
> more voltage once it warms up? Any chance that replacing the tube will
> help?
>
> 2. Any other ideas or suggestions?
> Thanks, JV
Don't know what might be wrong, but I will pass this along. I had a
600m that worked fine with an external monitor, but the LCD showed color
corruption. Replacing the motherboard was what fixed it, not the LCD,
not the cable.
If you decide to try any more parts, you might check e-bay, unless it is
under warranty.
"John Vallelunga" <johnv@sonic.net> wrote in message
news:4817bbc1$0$34553$742ec2ed@news.sonic.net...
> My wife's 700m laptop backlight will light up when first turned on,
> but then shuts down after 30-200 seconds. An external display works
> fine. I assumed this was an inverter problem and bought a new one. I
> replaced it today, but the problem remains. And yes, all the
> connectors seem to be solid.
>
> After some research, others have suggested the lid-closure switch
> could be the culprit, but this switch seems to be working just fine.
> I can boot to the bios and see the backlight come on and off as I
> activate the switch (this assumes I do it within the 30-200 seconds
> that it works.)
>
> Two questions:
> 1. Can a bad backlight tube cause this problem? It seems to work
> fine, and has normal brightness when it works. Could it be taking too
> much current which makes the inverter stop working? Could it require
> more voltage once it warms up? Any chance that replacing the tube will
> help?
>
> 2. Any other ideas or suggestions?
> Thanks, JV
A friend had an Inspiron 3800 with those symptoms.
He got the tube replaced and it fixed it.
Eric Parker wrote:
>
> A friend had an Inspiron 3800 with those symptoms.
> He got the tube replaced and it fixed it.
>
> Eric
>
>
You might be on to something here.
I tried a tube from another old display and, although it was not the
right size, it did remain lit.
I am going to order one now. Thanks
jv
"John Vallelunga" <johnv@sonic.net> wrote in message
news:481a8be3$0$34519$742ec2ed@news.sonic.net...
> Eric Parker wrote:
>>
>> A friend had an Inspiron 3800 with those symptoms.
>> He got the tube replaced and it fixed it.
>>
>> Eric
>>
>>
> You might be on to something here. I tried a tube from another old
> display and, although it was not the right size, it did remain lit. I
> am going to order one now. Thanks
> jv
i would suspect that the problem is indeed the floresent lamp. and though
the replacement bulb is cheap this operation is not for the ocasional
tinkerer... there is a lot os disessembly involved, but most critical are
the layers of plastic that lay over the lcd panel which can easily get out
of alignment and effectively ruin the display. i suggest you check out this
lcd repair shop for reasonable rates to do the replacement for you... they
also sell bulbs if you want to go that route. http://moniserv.com/
"John Vallelunga" <johnv@sonic.net> wrote in message
news:481923c1$0$34547$742ec2ed@news.sonic.net...
> Eric Parker wrote:
>>
>> A friend had an Inspiron 3800 with those symptoms.
>> He got the tube replaced and it fixed it.
>>
>> Eric
>>
>>
>
> hmmm....Interesting. Well a new tube only costs $10 (+ shipping) so it is
> probably worth the gamble. Anyone else fix this the same way?
>
> JV
Christopher Muto wrote:
> i would suspect that the problem is indeed the floresent lamp. and though
> the replacement bulb is cheap this operation is not for the ocasional
> tinkerer... there is a lot os disessembly involved, but most critical are
> the layers of plastic that lay over the lcd panel which can easily get out
> of alignment and effectively ruin the display. i suggest you check out this
> lcd repair shop for reasonable rates to do the replacement for you... they
> also sell bulbs if you want to go that route.
> http://moniserv.com/
>
Well, I hope to be able to fix this myself. I ordered the tube already
and it should be here by Monday. As it happens, I ordered it from
Moniserv. I am used to taking things apart, and am an EE, so I am
hopeful. The display I took apart to try the experiment was very
simple...the tube assembly just slid right out....no skills necessary.
I will let you know how it goes.
"John Vallelunga" <johnv@sonic.net> wrote in message
news:481bd3a0$0$34529$742ec2ed@news.sonic.net...
> Christopher Muto wrote:
>> i would suspect that the problem is indeed the floresent lamp. and
>> though the replacement bulb is cheap this operation is not for the
>> ocasional tinkerer... there is a lot os disessembly involved, but most
>> critical are the layers of plastic that lay over the lcd panel which can
>> easily get out of alignment and effectively ruin the display. i suggest
>> you check out this lcd repair shop for reasonable rates to do the
>> replacement for you... they also sell bulbs if you want to go that route.
>> http://moniserv.com/
>>
> Well, I hope to be able to fix this myself. I ordered the tube already
> and it should be here by Monday. As it happens, I ordered it from
> Moniserv. I am used to taking things apart, and am an EE, so I am
> hopeful. The display I took apart to try the experiment was very
> simple...the tube assembly just slid right out....no skills necessary. I
> will let you know how it goes.
>
> JV
some are easier than others, and i don't have intimate knowledge of the 700m
bulb installation, but the problems i have had are not so much with the bulb
installation (though i found soldering such a delicate thing in place a bit
scary, not wanting to overheat it) but the film on the front on the lcd
panel... if that stuff gets disturbed then the light just doesn't get
carried across the entire screen correctly and looks horrible... but the
great thing about working on something that is broken is that you can't make
it much worse. best of luck, and look forward to hearing your success
story.
Re: 700m laptop backlight fails after 1 min. SH*T!!!
Christopher Muto wrote:
> "John Vallelunga" <johnv@sonic.net> wrote in message
> news:481bd3a0$0$34529$742ec2ed@news.sonic.net...
>
>> Christopher Muto wrote:
>>
>>> i would suspect that the problem is indeed the floresent lamp. and
>>> though the replacement bulb is cheap this operation is not for the
>>> ocasional tinkerer... there is a lot os disessembly involved, but most
>>> critical are the layers of plastic that lay over the lcd panel which can
>>> easily get out of alignment and effectively ruin the display. i suggest
>>> you check out this lcd repair shop for reasonable rates to do the
>>> replacement for you... they also sell bulbs if you want to go that route.
>>> http://moniserv.com/
>>>
>>>
>> Well, I hope to be able to fix this myself. I ordered the tube already
>> and it should be here by Monday. As it happens, I ordered it from
>> Moniserv. I am used to taking things apart, and am an EE, so I am
>> hopeful. The display I took apart to try the experiment was very
>> simple...the tube assembly just slid right out....no skills necessary. I
>> will let you know how it goes.
>>
>> JV
>>
>
> some are easier than others, and i don't have intimate knowledge of the 700m
> bulb installation, but the problems i have had are not so much with the bulb
> installation (though i found soldering such a delicate thing in place a bit
> scary, not wanting to overheat it) but the film on the front on the lcd
> panel... if that stuff gets disturbed then the light just doesn't get
> carried across the entire screen correctly and looks horrible... but the
> great thing about working on something that is broken is that you can't make
> it much worse. best of luck, and look forward to hearing your success
> story.
>
>
Well Sh!t! I got the tube today and I must admit this was a very
difficult job. I am very used to working with microelectronics (over
30years), but this had me pretty much beat. The tube on these is very
difficult to remove. I was hoping for something much easier...like the
display I took apart to test it. This 700m display is extremely
difficult and without instructions, I would never attempt it again.
On the bright side (no pun intended), I did manage to replace the tube
and it did solve the problem of the light going off after a minute or
so. So if you have this problem SEND YOUR UNIT IN for a tube
replacement! The laptop works just fine now except for one minor
problem that I caused. Somewhere in the process, and I have no idea how,
I managed to crack the display in a corner. I now have a working
display except for a big hole in the corner....but the other 95% works.
Oh well. My wife has already ordered a replacement laptop (she did not
think I could fix it) and it should be shipped this week. I guess this
unit will go on ebay AS-IS. It would be a great server and it works
great with an external monitor.
What a bummer!
700m laptop backlight fails after 1 min. 
Linear Mode
