Bdtyktl

I have a Packard Bell LM85 laptop that is not new (about 8 years). It is a great laptop and I want to keep it.

Some time ago it started to have problems with starting up.

When I press the power button:

• The power PED turns on


• The montherboard fan spins up


• The hard drive spins up and shows access activity for a second (a separate LED)


• The CD is polled (the noise is audible; there is no CD inserted)


• And nothing else happens. The screen back light does not turn on, nothing appears on the screen, the hard drive keeps spinning but shows no further access activity.

The laptop will then sit in this "zombie mode" indefinitely.

I've tried turning on printing of verbose BIOS information on a startup, but nothing prints (apparently the issue occurs before the BIOS starts its check). I've tried connecting an external display to the video outputs in case BIOS prints something but I cannot see it because the laptop screen fails to turn on, but nothing appeared there too.

The problem can happen regardless of the startup mode (cold boot, resuming from hibernation, resuming from sleep mode).

However, the problem does not happen all the time, but often enough to be very annoying and prohibit the use of the Sleep mode.

If the laptop starts booting up successfully, there is absolutely no further problems with it. It works perfectly and does not try to switch off by itself (like e.g. here).

Having done numerous experiments that included adding and removing hardware components, I have arrived to the following conclusions:

• In order to start the laptop, I need to let it sit in the "zombie mode" for a little while (less than a minute), as if it required some sort of internal warmup. After that I switch it off and on again, and it starts up normally.


• The only thing that affects the chance of entering the "zombie mode" is the ambient temperature, to which the laptop seems to now be extremely sensitive:
  
  
  
  
  • If it sits for several hours in a room at about 20° C (68° F), it will most likely enter the "zombie state" when switched on.
  
  
  • If it sits for several hours in a room at about 25° C (77° F), it will most likely start up normally.
  
  
  
  

Which really puzzles me. It this kind of sensitivity something that is even heard of, or was it a coincidence? And if it wasn't, what could the culprit?

I have carefully examined the motherboard, and to the best of my knowledge, I cannot see any leaked or swollen elements. The only change I could see is that the board around the graphics chip had gone yellow, which I attribute to a failed fan that I had to replace three years ago and had no problems with since then.

This answer has absolutely no evidence to support it, is pure guesswork & the best that can be said is 'it worked for me'. So... ymmv.

I had a desktop with similar behaviour.

After months of prodding, poking & idle speculation I grasped at a potential root cause based on little to no real evidence.

What if, I thought, the HD platter's dimensions are affected by the temperature sufficiently that any electro-mechanical compensation built into the device can't quite adjust far enough when it's cold?

If that's the case, then how do I compensate for that, short of buying a heater.

What if I low-level format? Maybe that would 're-calibrate the hardware'?

I know low-level isn't really the same these days as it was, but it would re-address the whole drive & map out bad sectors.

I could start it on the drive when cold, & even though it would heat up during the process, maybe, just maybe, starting from cold might work.

Armed with the vague impression I might be doing more good than harm, even if the snake oil factor was potentially high, I cloned the drive when warm, then let it cool.

Low-level format, then cloned back.

Well, whaddaya know... it worked.

(This, of course, in no way proves my vague theory was correct ;)

It was a hardware problem related to power circuits on the motherboard feeding the graphics chip. It took an experienced technician slightly over an hour to diagnose and fix it with some soldering.

My previous statement of:

If the laptop starts booting up successfully, there is absolutely no further problems with it.

turns out to not actually be true. There was a problem: the area around the graphics chip was heating much more than it should have been. I did not realise it because it slowly got hotter and hotter over a year or so.

Now that the circuit is fixed, not only the laptop starts up like it should regardless the temperature, but I cannot even feel any heat coming through the keyboard.

It kept getting worse with time too, in the last two weeks the laptop required 25 minutes of warmup before it would be able to start.