Re: PB170 Tunnel Vision

[Steve Pullan]

Tom/Roger,

Thanks for your prompt replies.

I also have a PB140 of the same vintage (and from the same 'Dreaded
Previous Owner') as the PB170, and its LCD has no problems.  (I know
it's also an active-matrix in the 170 vs. passive in the 140.)

The backlight in the 170 is very bright - just like new and the LCD
starts off looking 100%.  The darkening occurs quite rapidly over about
15 mins.

I thought at first it was due to heat from the backlight so I turned the
b/l off and left it overnight, but the tunnel vision remained.

Tom's theory of contamination sounds right to me, although living in
Australia I have no way of getting the screen to you.  I also presume it
would be a destructive test to verify the theory?

The aforementioned 'DPO' told me that the 170 used to refuse to startup
properly so he heated it with a hair dryer and when it got warm it burst
into life.  I have later pinpointed this to a faulty power supply plug
(the one that plugs into the PB) on the wall adapter - it had a hairline
open circuit which closed when heated.  I have no doubt that this
heating has had an adverse affect on the LCD.

Regards,

...Steve

 


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Re: PB170 Tunnel Vision

[Steve Pullan]

Tom/Roger,

Thanks for your prompt replies.

I also have a PB140 of the same vintage (and from the same 'Dreaded
Previous Owner') as the PB170, and its LCD has no problems.  (I know
it's also an active-matrix in the 170 vs. passive in the 140.)

The backlight in the 170 is very bright - just like new and the LCD
starts off looking 100%.  The darkening occurs quite rapidly over about
15 mins.

I thought at first it was due to heat from the backlight so I turned the
b/l off and left it overnight, but the tunnel vision remained.

Tom's theory of contamination sounds right to me, although living in
Australia I have no way of getting the screen to you.  I also presume it
would be a destructive test to verify the theory?

The aforementioned 'DPO' told me that the 170 used to refuse to startup
properly so he heated it with a hair dryer and when it got warm it burst
into life.  I have later pinpointed this to a faulty power supply plug
(the one that plugs into the PB) on the wall adapter - it had a hairline
open circuit which closed when heated.  I have no doubt that this
heating has had an adverse affect on the LCD.

Regards,

...Steve

 


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PB170 Tunnel Vision

[Steve Pullan]

Hi all,
 
I have an old PowerBook 170 that I’m trying to resurrect but it has an
LCD problem.
 
It has light shadowy tinges to the extremes of the display which get
darker and grow inwards after a while of use, so much so that it looks
like you have tunnel vision with only the middle 2/3 of the screen (an
oval in the middle) visible.
 
Is this a common problem, and is it fixable (other than replacing the
LCD)?
 
Thanks.
 
…Steve
 



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