Replacing Hall Effects Transistor

[Jack B. Pollack]

I just inherited an old MacBook G3 Laptop.The problem with the laptop is
that it always thinks that the cover is closed. All of the documentation I
have found on the net say that there is a reed switch that controls this
behavior. On my system it actually is a Hall Effects transistor for some
reason.

I haven't been able to find this part on ebay or elsewhere (I don't know the
Apple part num, just searched for G3 Hall effects). Is there a general
purpose Hall Effects transistor (I can get from Mouser etc.) that might
work, or do I need a specific replacement?

The markings on the surface-mount component is 13E if that helps?

When I short the bottom 2 legs of the transistor the unit does not go to
sleep. If I cant find a replacement I just want to disable this feature. Can
I just short the transistor or am I better off using some value resistor
across it?

 

[Tim Wescott]

Jack B. Pollack wrote:

I just inherited an old MacBook G3 Laptop.The problem with the laptop is
that it always thinks that the cover is closed. All of the documentation I
have found on the net say that there is a reed switch that controls this
behavior. On my system it actually is a Hall Effects transistor for some
reason.

I haven't been able to find this part on ebay or elsewhere (I don't know the
Apple part num, just searched for G3 Hall effects). Is there a general
purpose Hall Effects transistor (I can get from Mouser etc.) that might
work, or do I need a specific replacement?

The markings on the surface-mount component is 13E if that helps?

When I short the bottom 2 legs of the transistor the unit does not go to
sleep. If I cant find a replacement I just want to disable this feature. Can
I just short the transistor or am I better off using some value resistor
across it?

Transistors aren't the only parts with three legs. It's an IC. Allegro
Microsystems (I _think_ that's the right name) makes hall effect ICs;
you may be able to search their site and get a close match.

It's probably perfectly safe to just short those legs, or at least if
you were going to break anything by doing the test you've probably
already done it.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[Jasen Betts]

On 2009-05-11, Jack B. Pollack <N@NE.nothing> wrote:

I just inherited an old MacBook G3 Laptop.The problem with the laptop is
that it always thinks that the cover is closed. All of the documentation I
have found on the net say that there is a reed switch that controls this
behavior. On my system it actually is a Hall Effects transistor for some
reason.

It's probably the hall effect sensor on all the macbooks.

I haven't been able to find this part on ebay or elsewhere (I don't know the
Apple part num, just searched for G3 Hall effects). Is there a general
purpose Hall Effects transistor (I can get from Mouser etc.) that might
work, or do I need a specific replacement?

The markings on the surface-mount component is 13E if that helps?

When I short the bottom 2 legs of the transistor the unit does not go to
sleep. If I cant find a replacement I just want to disable this feature. Can
I just short the transistor or am I better off using some value resistor
across it?

try this one:
http://www.newark.com/jsp/search/productdetail.jsp?sku=31K6622

 

[Jack B. Pollack]

"Tim Wescott" <tim@seemywebsite.com> wrote in message
news:OaidnfI7T-4mq5XXnZ2dnUVZ_smdnZ2d@web-ster.com...

Jack B. Pollack wrote:
I just inherited an old MacBook G3 Laptop.The problem with the laptop is
that it always thinks that the cover is closed. All of the documentation
I have found on the net say that there is a reed switch that controls
this behavior. On my system it actually is a Hall Effects transistor for
some reason.

I haven't been able to find this part on ebay or elsewhere (I don't know
the Apple part num, just searched for G3 Hall effects). Is there a
general purpose Hall Effects transistor (I can get from Mouser etc.) that
might work, or do I need a specific replacement?

The markings on the surface-mount component is 13E if that helps?

When I short the bottom 2 legs of the transistor the unit does not go to
sleep. If I cant find a replacement I just want to disable this feature.
Can I just short the transistor or am I better off using some value
resistor across it?

Transistors aren't the only parts with three legs. It's an IC. Allegro
Microsystems (I _think_ that's the right name) makes hall effect ICs; you
may be able to search their site and get a close match.

It's probably perfectly safe to just short those legs, or at least if you
were going to break anything by doing the test you've probably already
done it.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

Thanks. I started looking at allegromicro.com but there are a lot of parts
that it could be.
Jasen in the next post suggested one. Hopefully that one will work. Thanks
for pointing me in the correct direction.

 

[Jack B. Pollack]

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:gubml8$dop$1@reversiblemaps.ath.cx...

On 2009-05-11, Jack B. Pollack <N@NE.nothing> wrote:
I just inherited an old MacBook G3 Laptop.The problem with the laptop is
that it always thinks that the cover is closed. All of the documentation
I
have found on the net say that there is a reed switch that controls this
behavior. On my system it actually is a Hall Effects transistor for some
reason.

It's probably the hall effect sensor on all the macbooks.

I haven't been able to find this part on ebay or elsewhere (I don't know
the
Apple part num, just searched for G3 Hall effects). Is there a general
purpose Hall Effects transistor (I can get from Mouser etc.) that might
work, or do I need a specific replacement?

The markings on the surface-mount component is 13E if that helps?

When I short the bottom 2 legs of the transistor the unit does not go to
sleep. If I cant find a replacement I just want to disable this feature.
Can
I just short the transistor or am I better off using some value resistor
across it?

try this one:
http://www.newark.com/jsp/search/productdetail.jsp?sku=31K6622

Thanks. As I commented in the previous post I found allegromicro.com but
wasn't sure which part to choose. The description of the part you suggests
sounds correct. Thanks so much