"J. P. Gilliver (John)" wrote:

For another friend, this (Vista era, but more than adequate for her
needs) 17" laptop. Virtually new condition, as she took care of it.

When power supply connected, blue line through power button, and light
on front, lights.

When power button pressed, ring comes on (lights up) around power
button, and another light on front lights. This and all subsequent
description applies whether on external or battery power; the only
difference external power makes is the light line in the power switch
and the light at the front. (System seems to have charged the battery.)

Nothing happens on screen - no even sign of backlight coming on.
(Thought - _could_ be screen/backlight, but we don't get Windows sounds
after the usual delay either, so I think it's mobo/processor. Have tried
with external monitor [no display], but not sure at what point
Fn-key-plus-F-key-to-change-monitors works.)

Although a backlamp is used to shine through the LCD panel, you can also
take a bright flashlight and shine it onto the outside of the LCD panel.
If you can see a screen image using the flashlight, the LCD panel is
getting the signal but the backlamp(s) is(are) broken. While they can
be replaced by the user, that requires disassembling the case, some
soldering skill, and a replacement backlamp kit with the correct bulbs.

Fan runs; DVD drive makes its usual twitch.

Does the laptop have a VGA port for an external monitor hook up? If so,
try that to see if video is working. You may have to hit an Fn key
combo to toggle on/off the external video output. The laptop manual
should tell you how to use the external video port.

The two things that make me think it's not completely dead:
o pressing a button on the left that has a picture on it that could be
an SD card makes that button flash for a second or two.
o turning the machine off (i. e. back to dead [DVD won't eject, no
lights other than external power if connected, fan stops]) by holding
the power button in works, _but requires it to be held in for several
seconds_.

4 seconds is the standard delay when holding the Power button to
forcibly kill the OS and make the hardware force a power off.

Not important - we've written it off, and ordered a replacement (a
Compaq; nobody had a 7535G for sale, other than a broken one or a
motherboard, both of which we decided were too much bother to try, given
the asking price), but if anyone _does_ know anything about this, it'd
be intellectually satisfying to fix it.

You might find Youtube videos on that model or similar ones so you can
see how to dismantle the case to get at the backlamps (if that is the
problem as exposed by using the flashlight). There are also Youtube
videos on how to replace the backlamps. While there you might as well
as also replace the inverter. When the backlamps begin to fail, they
draw more current which taxes the inverter. You could end up going
through all the work to replace just the backlamps and then soon later
end up having to do the inverter, too, which means having to dismantle
and reassemble the mess again.

I forget the place but I did find a shop that would list the laptop
brand and model and sell replacement kits for the backlamps. They
didn't just sell the bulbs. They also include a small coil of solder,
butyl tape (sometimes used to hold the bulbs in place), some other tape
(forget what it was for but disassembling around the LCD panel results
in having to peel off some tape that obviously won't stick as well when
reused). They would even list replacement kits that used bulbs that
drew less current but output more light (i.e., they were more efficient)
so you'd have a brighter display. I'd have to search again to find that
place.

However, by the time I looked at the price for the backlamp kit, and
because my model had 4 bulbs (top, bottom, both sides) instead of just
on the 2 sides, it was more cost than worth it to me.

You might give the unit away on Craigslist. I've seen some folks that
buy this stuff and fix it to donate to a charity or low income folks.
It's a hobby while satisfying their urge to help others. Some may take
the laptop off your hands just to add to their inventory of spare parts.
In any case, you don't have to haul it to your local hazardous waste
recycle center to get rid of it.

In my case, there was no gradual dimming of the bulbs to let me know
they were going bad and would eventually die. One day the screen just
went poof: all black. Not even the BIOS POS screen showed up. I
suspect the inverter blew to cause the instantaneous outage. However,
if I was going through all the dismantling to get at the inverter then I
might as well as replace the bulbs while I was right there. I was
actually using the old laptop as a temporary substitute when my desktop
went poof (mobo problem). After rebuilding the desktop, I didn't need
the laptop anymore and its hardware was too old and slow to bother
fixing. Got rid of it on Craigslist (to a guy does the repairs and then
donates).