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How do you test a backlight ? IBM a31p

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  How do you test a backlight ? IBM a31p mike <spamme9@gmail.com> - 2012-08-29 17:01 -0700
    Re: How do you test a backlight ? IBM a31p BillW50 <BillW50@aol.kom> - 2012-08-29 20:12 -0500
      Re: How do you test a backlight ? IBM a31p mike <spamme9@gmail.com> - 2012-08-29 19:15 -0700
        Re: How do you test a backlight ? IBM a31p "BillW50" <BillW50@aol.kom> - 2012-08-30 05:42 -0500
          Re: How do you test a backlight ? IBM a31p mike <spamme9@gmail.com> - 2012-08-30 05:55 -0700
            Re: How do you test a backlight ? IBM a31p BillW50 <BillW50@aol.kom> - 2012-08-30 10:25 -0500
              Re: How do you test a backlight ? IBM a31p mike <spamme9@gmail.com> - 2012-08-30 08:33 -0700
                Re: How do you test a backlight ? IBM a31p BillW50 <BillW50@aol.kom> - 2012-08-30 11:08 -0500
                  Re: How do you test a backlight ? IBM a31p BillW50 <BillW50@aol.kom> - 2012-08-30 11:33 -0500
                    Re: How do you test a backlight ? IBM a31p mike <spamme9@gmail.com> - 2012-08-30 10:43 -0700
                      Re: How do you test a backlight ? IBM a31p BillW50 <BillW50@aol.kom> - 2012-08-30 17:19 -0500
                  Re: How do you test a backlight ? IBM a31p mike <spamme9@gmail.com> - 2012-08-30 10:37 -0700
                    Re: How do you test a backlight ? IBM a31p BillW50 <BillW50@aol.kom> - 2012-08-30 17:06 -0500
                  Re: How do you test a backlight ? IBM a31p wrat@panix.com (the wharf rat) - 2012-09-01 06:33 +0000
                    Re: How do you test a backlight ? IBM a31p BillW50 <BillW50@aol.kom> - 2012-09-01 12:36 -0500

#1518 — How do you test a backlight ? IBM a31p

I've got a Thinkpad a31p with no backlight.

I put another backlight on the inverter and got no light.
I tried the Thinkpad backlight on another inverter and got no light.
Initial guess is both bad.
Is there any reason the Thinkpad light should be different from any other?
I put a 1M resistor in series with a DC power supply.
A Toshiba backlight fires at about 1500V and stays lit
back down to 1000V or so.

The Thinkpad light starts drawing current at about 1500V
but doesn't light.  I'm trying to think of a failure mode
that would cause this behavior.  If the bulb is cracked,
wouldn't is just be an open circuit at any rational voltage?

Is there a source for schematics or reference inverter designs?
IBM put LED indicators on the inverter board, so you can't just
cobble in another.  They're rare and more expensive than buying
a whole used A31p.
It's got the 1600x1200 display, so it's worth some effort to try
to fix it.

According to the service manual. There are several ways to turn
off the display, but I'm assuming that if there's data on the display,
the backlight should always be on???

The service manual mentions that fuses aren't covered under warranty,
but there's no mention of a fuse anywhere.
I once had a thinkpad with a bad display fuse.  Haven't taken it
that far apart yet.

Suggestions?
Thanks, mike

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#1519

On 8/29/2012 7:01 PM, mike wrote:
> I've got a Thinkpad a31p with no backlight.
>
> I put another backlight on the inverter and got no light.
> I tried the Thinkpad backlight on another inverter and got no light.
> Initial guess is both bad.
> Is there any reason the Thinkpad light should be different from any other?
> I put a 1M resistor in series with a DC power supply.
> A Toshiba backlight fires at about 1500V and stays lit
> back down to 1000V or so.

You used a DC power supply and cranked it up to 1500V? And you used a 
one megohm resistor in series with the power supply? I am not sure that 
would work even if everything works fine.

As once a florescent tube fires and ionizes, the internal resistance 
drops really fast. And the trick of the inverter is to get the tube 
working partly shorted and open by pulsating the voltage. Straight DC 
voltage won't work. How they regulate this pulsing, I do not know 
exactly how they work the timing.

At first, I understood that a tube and an inverter were matched. 
Although later I learned from others who didn't follow that belief who 
said this. Inverters are matched to a given length and diameter of a 
tube. And they say you can cheat a bit. Like taking an inverter 15.4 
inch tube and using it on a 14 inch or something. But that is pushing it 
a bit.

> The Thinkpad light starts drawing current at about 1500V
> but doesn't light.  I'm trying to think of a failure mode
> that would cause this behavior.  If the bulb is cracked,
> wouldn't is just be an open circuit at any rational voltage?

Well a tube not firing, ionizing is going to act totally open. And if 
you monitor the current flow, you will see none. The tube doesn't have 
to be cracked or anything. Tubes generally have a lifespan of 25,000 to 
30,000 hours. Once they get this old, they get dimmer and dimmer and 
then at some point may start sometimes or not. Then one day, it will 
never fire.

> Is there a source for schematics or reference inverter designs?
> IBM put LED indicators on the inverter board, so you can't just
> cobble in another.  They're rare and more expensive than buying
> a whole used A31p.
> It's got the 1600x1200 display, so it's worth some effort to try
> to fix it.
>
> According to the service manual. There are several ways to turn
> off the display, but I'm assuming that if there's data on the display,
> the backlight should always be on???

Speaking about most laptops in general. They can turn off through the 
lid switch (usually magnetic reed switch) or if the external monitor 
port is in use. Some can be disabled through the BIOS settings. Of 
course, Windows can turn it off too.

> The service manual mentions that fuses aren't covered under warranty,
> but there's no mention of a fuse anywhere.
> I once had a thinkpad with a bad display fuse.  Haven't taken it
> that far apart yet.
>
> Suggestions?
> Thanks, mike

I don't think you will find replaceable fuses in a laptop. They should 
be all those surface mounted fuses. If you have replaced components on a 
motherboard before, you should be good to go. If you haven't, well a 
laptop would not be my first choice to practice on.

-- 
Bill
Gateway M465e ('06 era) - Thunderbird v14
Centrino Core2 Duo T5600 1.83GHz - 4GB - Windows XP SP2

[toc] | [prev] | [next] | [standalone]

#1520

On 8/29/2012 6:12 PM, BillW50 wrote:
> On 8/29/2012 7:01 PM, mike wrote:
>> I've got a Thinkpad a31p with no backlight.
>>
>> I put another backlight on the inverter and got no light.
>> I tried the Thinkpad backlight on another inverter and got no light.
>> Initial guess is both bad.
>> Is there any reason the Thinkpad light should be different from any
>> other?
>> I put a 1M resistor in series with a DC power supply.
>> A Toshiba backlight fires at about 1500V and stays lit
>> back down to 1000V or so.
>
> You used a DC power supply and cranked it up to 1500V? And you used a
> one megohm resistor in series with the power supply? I am not sure that
> would work even if everything works fine.

Well, the paragraph above says that it does work: fires 1500V drops out 
at 1kv or so...that's volts into the resistor.  I hadn't built the high
voltage probe to check the lamp voltage.  That's next.
>
> As once a florescent tube fires and ionizes, the internal resistance
> drops really fast. And the trick of the inverter is to get the tube
> working partly shorted and open by pulsating the voltage. Straight DC
> voltage won't work. How they regulate this pulsing, I do not know
> exactly how they work the timing.

There may be service life issues with DC, but it definitely works. see 
above.
>
> At first, I understood that a tube and an inverter were matched.
> Although later I learned from others who didn't follow that belief who
> said this. Inverters are matched to a given length and diameter of a
> tube. And they say you can cheat a bit. Like taking an inverter 15.4
> inch tube and using it on a 14 inch or something. But that is pushing it
> a bit.
>
>> The Thinkpad light starts drawing current at about 1500V
>> but doesn't light. I'm trying to think of a failure mode
>> that would cause this behavior. If the bulb is cracked,
>> wouldn't is just be an open circuit at any rational voltage?
>
> Well a tube not firing, ionizing is going to act totally open. And if
> you monitor the current flow, you will see none.

Like I said in the above paragraph.  It's drawing current, just not 
lighting.
And it displays the negative resistance effect, just not lighting.


The tube doesn't have
> to be cracked or anything. Tubes generally have a lifespan of 25,000 to
> 30,000 hours. Once they get this old, they get dimmer and dimmer and
> then at some point may start sometimes or not. Then one day, it will
> never fire.

My understanding of the theory is that the firing voltage goes up with age
and the inverter can't put out enough to get it started.
The plasma is either ionized or it isn't.  If it's ionized, it oughta be
putting out some light?  Maybe not much, maybe it's pink, but oughta see
something?
>
>> Is there a source for schematics or reference inverter designs?
>> IBM put LED indicators on the inverter board, so you can't just
>> cobble in another. They're rare and more expensive than buying
>> a whole used A31p.
>> It's got the 1600x1200 display, so it's worth some effort to try
>> to fix it.
>>
>> According to the service manual. There are several ways to turn
>> off the display, but I'm assuming that if there's data on the display,
>> the backlight should always be on???
>
> Speaking about most laptops in general. They can turn off through the
> lid switch (usually magnetic reed switch) or if the external monitor
> port is in use. Some can be disabled through the BIOS settings. Of
> course, Windows can turn it off too.

As I stated in the above paragraph, if there's data on the display,
shouldn't the backlilght be on?  Anything that turns off the backlight
oughta also turn off the data to the display???  I'd hate to chase my
tail only to find out I hadn't pushed some key.
>
>> The service manual mentions that fuses aren't covered under warranty,
>> but there's no mention of a fuse anywhere.
>> I once had a thinkpad with a bad display fuse. Haven't taken it
>> that far apart yet.
>>
>> Suggestions?
>> Thanks, mike
>
> I don't think you will find replaceable fuses in a laptop. They should
> be all those surface mounted fuses.

Said nothing about the type of fuse, just asked if they often exist.
The only display fuse I've ever seen was on a thinkpad, but I've never
really looked for fuses.
  If you have replaced components on a
> motherboard before, you should be good to go. If you haven't, well a
> laptop would not be my first choice to practice on.
Been designing/fixing this stuff for decades.
I'd rather not have to reverse engineer the thing if info is available.

The chip is marked HL397 3456.  Google has failed me finding a datasheet
or reference design related to it.
>

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#1523

On 8/29/2012 9:15 PM, mike wrote:
> On 8/29/2012 6:12 PM, BillW50 wrote:
>> On 8/29/2012 7:01 PM, mike wrote:
>>> I've got a Thinkpad a31p with no backlight.
>>>
>>> I put another backlight on the inverter and got no light.
>>> I tried the Thinkpad backlight on another inverter and got no light.
>>> Initial guess is both bad.
>>> Is there any reason the Thinkpad light should be different from any
>>> other?
>>> I put a 1M resistor in series with a DC power supply.
>>> A Toshiba backlight fires at about 1500V and stays lit
>>> back down to 1000V or so.
>>
>> You used a DC power supply and cranked it up to 1500V? And you used a
>> one megohm resistor in series with the power supply? I am not sure
>> that would work even if everything works fine.
>
> Well, the paragraph above says that it does work: fires 1500V drops
> out at 1kv or so...that's volts into the resistor.  I hadn't built
> the high voltage probe to check the lamp voltage.  That's next.

Sounds good to me. What I hear a lot is that inverters generally put out
like 1800v unloaded and about 800v when the lamp is lit. So a value
similar is what I would expect.

>> As once a florescent tube fires and ionizes, the internal resistance
>> drops really fast. And the trick of the inverter is to get the tube
>> working partly shorted and open by pulsating the voltage. Straight DC
>> voltage won't work. How they regulate this pulsing, I do not know
>> exactly how they work the timing.
>
> There may be service life issues with DC, but it definitely works. see
> above.

That is very good to know. ;-)

>> At first, I understood that a tube and an inverter were matched.
>> Although later I learned from others who didn't follow that belief
>> who said this. Inverters are matched to a given length and diameter
>> of a tube. And they say you can cheat a bit. Like taking an inverter
>> 15.4 inch tube and using it on a 14 inch or something. But that is
>> pushing it a bit.
>>
>>> The Thinkpad light starts drawing current at about 1500V
>>> but doesn't light. I'm trying to think of a failure mode
>>> that would cause this behavior. If the bulb is cracked,
>>> wouldn't is just be an open circuit at any rational voltage?
>>
>> Well a tube not firing, ionizing is going to act totally open. And if
>> you monitor the current flow, you will see none.
>
> Like I said in the above paragraph.  It's drawing current, just not
> lighting.
> And it displays the negative resistance effect, just not lighting.

It could be like some switching supplies draw current unloaded, while
some truly draw nothing at all.

>> The tube doesn't have to be cracked or anything. Tubes generally have
>> a lifespan of 25,000 to 30,000 hours. Once they get this old, they
>> get dimmer and dimmer and then at some point may start sometimes or
>> not. Then one day, it will never fire.
>
> My understanding of the theory is that the firing voltage goes up
> with age and the inverter can't put out enough to get it started.
> The plasma is either ionized or it isn't.  If it's ionized, it oughta
> be putting out some light?  Maybe not much, maybe it's pink, but
> oughta see something?

Yes that is my understanding too. Although I suspect at some point no
matter how much voltage you feed it, it just won't ionize.

>>> Is there a source for schematics or reference inverter designs?

Sadly, manufactures nowadays keep these under lock and key. They seem to
be really worried that their competitors stealing their designs.

>>> IBM put LED indicators on the inverter board, so you can't just
>>> cobble in another. They're rare and more expensive than buying
>>> a whole used A31p.
>>> It's got the 1600x1200 display, so it's worth some effort to try
>>> to fix it.

eBay is usually a good place to find used working parts. For some things
anyway. Like these Gateway M465, zillions have come off lease and I can
buy perfectly working ones all day long for about $50 a piece off of
eBay.

>>> According to the service manual. There are several ways to turn
>>> off the display, but I'm assuming that if there's data on the
>>> display, the backlight should always be on???
>>
>> Speaking about most laptops in general. They can turn off through the
>> lid switch (usually magnetic reed switch) or if the external monitor
>> port is in use. Some can be disabled through the BIOS settings. Of
>> course, Windows can turn it off too.
>
> As I stated in the above paragraph, if there's data on the display,
> shouldn't the backlilght be on?  Anything that turns off the backlight
> oughta also turn off the data to the display???  I'd hate to chase my
> tail only to find out I hadn't pushed some key.

I don't think that is always true. For example most laptops if you close
the lid, the lamp turns off. But I believe the display itself is still
functioning. Although I haven't experimented to test this or anything.
Another test would be to have Windows turn off the display. Then with a
flashlight, spotlight, or even sunlight you should be able to make out
part of the image if it is still functioning. Anything white is very
easier to see. Like having notepad or something on the screen should
make this much easier to check.

My old Toshiba 2595XDVD laptops from 1999 have a hotkey to turn off the
backlighting on the display. So at least some laptops it is possible
that it could be a key press away. I don't think it sticks if you reboot
though. As I believe it defaults to being on when powered up.

>>> The service manual mentions that fuses aren't covered under
>>> warranty, but there's no mention of a fuse anywhere.
>>> I once had a thinkpad with a bad display fuse. Haven't taken it
>>> that far apart yet.
>>>
>>> Suggestions?
>>> Thanks, mike
>>
>> I don't think you will find replaceable fuses in a laptop. They
>> should be all those surface mounted fuses.
>
> Said nothing about the type of fuse, just asked if they often exist.
> The only display fuse I've ever seen was on a thinkpad, but I've never
> really looked for fuses.

Yes they do exist on motherboards. I can't say they always exist on
every design though. But they are indeed common enough.

>> If you have replaced components on a motherboard before, you should
>> be good to go. If you haven't, well a laptop would not be my first
>> choice to practice on.
>
> Been designing/fixing this stuff for decades.

Ah good! ;-)

> I'd rather not have to reverse engineer the thing if info is
> available.

I know the feeling.

> The chip is marked HL397 3456.  Google has failed me finding a
> datasheet or reference design related to it.

This is the chip on the inverter, right? I haven't found anything here
either yet. But I'll continue checking.

-- 
Bill
Gateway M465e ('06 era) - OE-QuoteFix v1.19.2
Centrino Core2 Duo T5600 1.83GHz - 4GB - Windows XP SP2

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#1525

On 8/30/2012 3:42 AM, BillW50 wrote:
> On 8/29/2012 9:15 PM, mike wrote:
>> On 8/29/2012 6:12 PM, BillW50 wrote:
>>> On 8/29/2012 7:01 PM, mike wrote:
>>>> I've got a Thinkpad a31p with no backlight.
>>>>
>>>> I put another backlight on the inverter and got no light.
>>>> I tried the Thinkpad backlight on another inverter and got no light.
>>>> Initial guess is both bad.
>>>> Is there any reason the Thinkpad light should be different from any
>>>> other?
>>>> I put a 1M resistor in series with a DC power supply.
>>>> A Toshiba backlight fires at about 1500V and stays lit
>>>> back down to 1000V or so.
>>>
>>> You used a DC power supply and cranked it up to 1500V? And you used a
>>> one megohm resistor in series with the power supply? I am not sure
>>> that would work even if everything works fine.
>>
>> Well, the paragraph above says that it does work: fires 1500V drops
>> out at 1kv or so...that's volts into the resistor.  I hadn't built
>> the high voltage probe to check the lamp voltage.  That's next.
>
> Sounds good to me. What I hear a lot is that inverters generally put out
> like 1800v unloaded and about 800v when the lamp is lit. So a value
> similar is what I would expect.

Yep, that's why you need the 1M resistor.
I'm gonna clean off the bench and build a RC relaxation oscillator
with the CCFL as the negative resistance element and see if that
works to test lamps.
>
>>> As once a florescent tube fires and ionizes, the internal resistance
>>> drops really fast. And the trick of the inverter is to get the tube
>>> working partly shorted and open by pulsating the voltage. Straight DC
>>> voltage won't work. How they regulate this pulsing, I do not know
>>> exactly how they work the timing.
>>
>> There may be service life issues with DC, but it definitely works. see
>> above.
>
> That is very good to know. ;-)
>
>>> At first, I understood that a tube and an inverter were matched.
>>> Although later I learned from others who didn't follow that belief
>>> who said this. Inverters are matched to a given length and diameter
>>> of a tube. And they say you can cheat a bit. Like taking an inverter
>>> 15.4 inch tube and using it on a 14 inch or something. But that is
>>> pushing it a bit.
>>>
>>>> The Thinkpad light starts drawing current at about 1500V
>>>> but doesn't light. I'm trying to think of a failure mode
>>>> that would cause this behavior. If the bulb is cracked,
>>>> wouldn't is just be an open circuit at any rational voltage?
>>>
>>> Well a tube not firing, ionizing is going to act totally open. And if
>>> you monitor the current flow, you will see none.
>>
>> Like I said in the above paragraph.  It's drawing current, just not
>> lighting.
>> And it displays the negative resistance effect, just not lighting.
>
> It could be like some switching supplies draw current unloaded, while
> some truly draw nothing at all.
>
>>> The tube doesn't have to be cracked or anything. Tubes generally have
>>> a lifespan of 25,000 to 30,000 hours. Once they get this old, they
>>> get dimmer and dimmer and then at some point may start sometimes or
>>> not. Then one day, it will never fire.
>>
>> My understanding of the theory is that the firing voltage goes up
>> with age and the inverter can't put out enough to get it started.
>> The plasma is either ionized or it isn't.  If it's ionized, it oughta
>> be putting out some light?  Maybe not much, maybe it's pink, but
>> oughta see something?
>
> Yes that is my understanding too. Although I suspect at some point no
> matter how much voltage you feed it, it just won't ionize.

Yep, but it shouldn't draw any current either.
>

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#1526

On 8/30/2012 7:55 AM, mike wrote:
> On 8/30/2012 3:42 AM, BillW50 wrote:
>> On 8/29/2012 9:15 PM, mike wrote:
>>> On 8/29/2012 6:12 PM, BillW50 wrote:
>>>> On 8/29/2012 7:01 PM, mike wrote:
>>>>> I've got a Thinkpad a31p with no backlight.
>>>>>
>>>>> I put another backlight on the inverter and got no light.
>>>>> I tried the Thinkpad backlight on another inverter and got no light.
>>>>> Initial guess is both bad.
>>>>> Is there any reason the Thinkpad light should be different from any
>>>>> other?
>>>>> I put a 1M resistor in series with a DC power supply.
>>>>> A Toshiba backlight fires at about 1500V and stays lit
>>>>> back down to 1000V or so.
>>>>
>>>> You used a DC power supply and cranked it up to 1500V? And you used a
>>>> one megohm resistor in series with the power supply? I am not sure
>>>> that would work even if everything works fine.
>>>
>>> Well, the paragraph above says that it does work: fires 1500V drops
>>> out at 1kv or so...that's volts into the resistor.  I hadn't built
>>> the high voltage probe to check the lamp voltage.  That's next.
>>
>> Sounds good to me. What I hear a lot is that inverters generally put out
>> like 1800v unloaded and about 800v when the lamp is lit. So a value
>> similar is what I would expect.
>
> Yep, that's why you need the 1M resistor.
> I'm gonna clean off the bench and build a RC relaxation oscillator
> with the CCFL as the negative resistance element and see if that
> works to test lamps.

Say I was thinking more of this and wondering if 1M ohm would be a good 
choice. And I came up with 2.25 watts @ 1500v. Is this about what you 
came up with too? Isn't most midsized laptops using a 7 watt lamp? Just 
curious.

Ever heard those stories of people testing the lamps without anything to 
limit the current? I heard they explode. Although I am not sure they 
actually do. My guess is that the tube cracks.

Also the tubes in normal use get quite hot. And so oil from fingers, 
lint, etc. are bad news on the surface of the glass. I am not sure how 
critical it is, but keeping the glass pretty clean makes a lot of sense 
to me.

Another tip is that a simple AM radio makes for a cheap EMF meter. As 
say placing an AM radio close by and just closing and opening the lid 
should turn on and off the inverter. And if the inverter is somewhat 
working, you should hear a drastic change in the noise level of the AM 
radio. So it is a sneaky quick test to see if it is the lamp or inverter 
problem. Not a total tell all or anything. But it sure beats guessing 
anyway. ;-)

I have one laptop that I only use for testing purposes and normally dock 
it in one of my docking stations and use the external LCD display. But 
the internal display is extremely bad for EMF. As all AM radios and 
analog TVs (remember those?) within 50 feet are unusable from this 
beast. The lamp flickers a lot and the display actually tears in sync 
with the random flickering of the lamp. I should actually fix it one of 
these days when I have some free time. ;-)

-- 
Bill
Gateway M465e ('06 era) - Thunderbird v14
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 7 SP1

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#1527

On 8/30/2012 8:25 AM, BillW50 wrote:

>
> Say I was thinking more of this and wondering if 1M ohm would be a good
> choice. And I came up with 2.25 watts @ 1500v. Is this about what you
> came up with too? Isn't most midsized laptops using a 7 watt lamp? Just
> curious.
Don't need 7W, just need it to strike.  And the voltage across the resistor
is only the difference between the strike voltage and the sustain voltage.
>

>
> Another tip is that a simple AM radio makes for a cheap EMF meter. As
> say placing an AM radio close by and just closing and opening the lid
> should turn on and off the inverter. And if the inverter is somewhat
> working, you should hear a drastic change in the noise level of the AM
> radio. So it is a sneaky quick test to see if it is the lamp or inverter
> problem. Not a total tell all or anything. But it sure beats guessing
> anyway. ;-)
I just waive a scope probe around the area.
Ultrasonic translator (leak detector)  also works for listening to it.
>

The relaxation oscillator experiment was a bust.
I couldn't come up with a combination of peak current limiting
resistor and charge time constant resistor that I could trust
to work with any lamp.  Just not enough slop in the operating range.

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#1528

On 8/30/2012 10:33 AM, mike wrote:
> On 8/30/2012 8:25 AM, BillW50 wrote:
> Don't need 7W, just need it to strike.  And the voltage across the resistor
> is only the difference between the strike voltage and the sustain voltage.

Yes this is true. And I don't know for sure, but just guessing I would 
think the lamp should stay lit as low as 1/4 of a watt or so.

>> Another tip is that a simple AM radio makes for a cheap EMF meter. As
>> say placing an AM radio close by and just closing and opening the lid
>> should turn on and off the inverter. And if the inverter is somewhat
>> working, you should hear a drastic change in the noise level of the AM
>> radio. So it is a sneaky quick test to see if it is the lamp or inverter
>> problem. Not a total tell all or anything. But it sure beats guessing
>> anyway. ;-)
> I just waive a scope probe around the area.
> Ultrasonic translator (leak detector)  also works for listening to it.

Yup, although I was also thinking of others reading these posts too. ;-)

> The relaxation oscillator experiment was a bust.
> I couldn't come up with a combination of peak current limiting
> resistor and charge time constant resistor that I could trust
> to work with any lamp.  Just not enough slop in the operating range.

Oh darn! I usually for the past 30+ years buy more than one of the same 
model. No, not usually at once. But usually sometime later after I feel 
comfortable that they are a sound design. This takes a lot of extra work 
out of troubleshooting later too. Plus you have hardware backups as 
well. ;-)

Only one problem I have ran across so far that multiple models hasn't 
been easily solved so far. That is that I have 8 of these Gateway M465 
and three of them play 3D games at 1280x800 without problems. But 5 of 
them have game errors and such unless I drop the full screen down to 
800x600. I am still investigating why this is so. :-( To be frank, my 
five Alienware machines are far better at 3D games anyway, so that 
problem isn't high on the list of things to do. ;-)

-- 
Bill
Gateway M465e ('06 era) - Thunderbird v14
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 7 SP1

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#1529

You know another thing to think about Mike, is that I have thought about 
it myself when the next time an inverter or lamp fails of converting it 
over to LED back lighting. Although I haven't thought much about how I 
would design changing the brightness much yet. Hopefully I could work it 
so the same hotkeys still operate the brightness. ;-)

-- 
Bill
Gateway M465e ('06 era) - Thunderbird v14
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 7 SP1

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#1531

On 8/30/2012 9:33 AM, BillW50 wrote:
> You know another thing to think about Mike, is that I have thought about
> it myself when the next time an inverter or lamp fails of converting it
> over to LED back lighting. Although I haven't thought much about how I
> would design changing the brightness much yet. Hopefully I could work it
> so the same hotkeys still operate the brightness. ;-)
>
Give it up.
The electronics are easy.  For a one-off, cost is no object.
The optical problems are formidable.
Trying to get light coupled uniformly into that existing wedge-shaped white
plastic diffuser using packaged off-the-shelf LEDS is gonna be a
nightmare.

Even if you succeed, the only benefit will be to say, "look what I can do!"

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#1533

On 8/30/2012 12:43 PM, mike wrote:
> On 8/30/2012 9:33 AM, BillW50 wrote:
>> You know another thing to think about Mike, is that I have thought about
>> it myself when the next time an inverter or lamp fails of converting it
>> over to LED back lighting. Although I haven't thought much about how I
>> would design changing the brightness much yet. Hopefully I could work it
>> so the same hotkeys still operate the brightness. ;-)
>>
> Give it up.
> The electronics are easy.  For a one-off, cost is no object.
> The optical problems are formidable.
> Trying to get light coupled uniformly into that existing wedge-shaped white
> plastic diffuser using packaged off-the-shelf LEDS is gonna be a
> nightmare.
>
> Even if you succeed, the only benefit will be to say, "look what I can do!"

Ah ok! I really do like my LED backlighting displays better than my 
florescent displays. Maybe I'll just stick with having the manufacture 
taking care of that part. ;-)

-- 
Bill
Gateway M465e ('06 era) - Thunderbird v14
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 7 SP1

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#1530

On 8/30/2012 9:08 AM, BillW50 wrote:

>
> Only one problem I have ran across so far that multiple models hasn't
> been easily solved so far. That is that I have 8 of these Gateway M465
> and three of them play 3D games at 1280x800 without problems. But 5 of
> them have game errors and such unless I drop the full screen down to
> 800x600. I am still investigating why this is so. :-( To be frank, my
> five Alienware machines are far better at 3D games anyway, so that
> problem isn't high on the list of things to do. ;-)
>
I just chased my tail on a Dell GX260.  The thing worked fine with the 
default windows display driver, but kept crashing trying to install
linux.
So, I put windows back on it.  Then I installed the updated Intel
display driver.  Now, windows is crashing.

Turned out to be caused by mismatched RAM.  Ran memtest86 all day
without error.  Replaced both Simms with a matched set and problems went 
away.

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#1532

On 8/30/2012 12:37 PM, mike wrote:
> On 8/30/2012 9:08 AM, BillW50 wrote:
>
>>
>> Only one problem I have ran across so far that multiple models hasn't
>> been easily solved so far. That is that I have 8 of these Gateway M465
>> and three of them play 3D games at 1280x800 without problems. But 5 of
>> them have game errors and such unless I drop the full screen down to
>> 800x600. I am still investigating why this is so. :-( To be frank, my
>> five Alienware machines are far better at 3D games anyway, so that
>> problem isn't high on the list of things to do. ;-)
>>
> I just chased my tail on a Dell GX260.  The thing worked fine with the
> default windows display driver, but kept crashing trying to install
> linux.
> So, I put windows back on it.  Then I installed the updated Intel
> display driver.  Now, windows is crashing.
>
> Turned out to be caused by mismatched RAM.  Ran memtest86 all day
> without error.  Replaced both Simms with a matched set and problems went
> away.

Yup, that doesn't surprise me one bit. While I never caught memtest86 
missing bad RAM yet, nothing tests RAM better than popping in known good 
RAM. I too thought the game problem might be RAM related and no in my 
case, no difference. Even taking the working machines hard drive and 
putting it into the ones that doesn't still doesn't work. So that should 
rule out anything to do with software.

Well almost anyway. Since it appears Windows 7 and Windows 8, doesn't 
have this problem. It just has something to do with XP (both SP2 and 
SP3) on some of the M465 machines. I haven't checked motherboard 
revisions yet, but the CPU type might also be the culprit. As the 
machines with a Celeron M430 and T2400 work and the machines with T2300, 
T5600, or the T7400 doesn't.

-- 
Bill
Gateway M465e ('06 era) - Thunderbird v14
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 7 SP1

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#1535

In article <k1o35q$vtl$1@dont-email.me>, BillW50  <BillW50@aol.kom> wrote:
>
>Only one problem I have ran across so far that multiple models hasn't 
>been easily solved so far. That is that I have 8 of these Gateway M465 
>and three of them play 3D games at 1280x800 without problems. But 5 of 
>them have game errors and such unless I drop the full screen down to 
>800x600. I am still investigating why this is so. :-( To be frank, my 


	Do they all have the ATI graphics chip or are some using the
onboard Intel?  if they're all ATI then Gateway probably has it clocked
as fast as it will go, and like any chip when you stress a part by running
at the limit and add a task that requires high performance some of the things
exhibit discrepancies before others.

	Like overclocking CPUs, some are fine, some work until you do something
hard, and some never work.

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#1536

On 9/1/2012 1:33 AM, the wharf rat wrote:
> In article <k1o35q$vtl$1@dont-email.me>, BillW50  <BillW50@aol.kom> wrote:
>>
>> Only one problem I have ran across so far that multiple models hasn't
>> been easily solved so far. That is that I have 8 of these Gateway M465
>> and three of them play 3D games at 1280x800 without problems. But 5 of
>> them have game errors and such unless I drop the full screen down to
>> 800x600. I am still investigating why this is so. :-( To be frank, my
>
>
> 	Do they all have the ATI graphics chip or are some using the
> onboard Intel?  if they're all ATI then Gateway probably has it clocked
> as fast as it will go, and like any chip when you stress a part by running
> at the limit and add a task that requires high performance some of the things
> exhibit discrepancies before others.
>
> 	Like overclocking CPUs, some are fine, some work until you do something
> hard, and some never work.

All of them are running Intel 945GM integrated graphics. I thought about 
buying some with ATI, but I figured they would be more trouble than they 
are worth. The ATI ones don't seem to last too much past 5 years old either.

I do suspect it may have something to do with CPU clock speeds. I could 
verify this by swapping CPUs around. Also some machines will operate at 
60 or 75Hz refresh rates, while some only 75Hz is selectable. I didn't 
note which ones are which yet. As I tried setting the ones that work 
with games at 75Hz and it didn't cause any problems.

M430 machine 1.73GHz (does work with games)
1GB of RAM (512MB x2) PC5300 (Hynix)
BIOS 71.10
1024x768 LCD
Windows XP SP3

T2300 machines 1.66GHz (doesn't work with games)
with Windows 8  (does work with games)
1GB of RAM (512MB x2) PC4200 (Hynix)
BIOS 71.04
1280x800 LCD
Windows XP SP2 and Windows 8

T2400 machine 1.83GHz (does work with games)
4GB of RAM (2GB x2) PC5300 (Samsung)
BIOS 71.07
1280x800 LCD
Windows XP SP3

T5600 machine 1.83GHz (doesn't work with games)
4GB of RAM (2GB x2) PC6400 (Adata)
BIOS 71.10
1280x800 LCD
Windows XP SP2

T7400 machine 2.16GHz (does work with games)
with XP  (doesn't work with games)
4GB of RAM (2GB x2) PC6400 (Hynix)
BIOS 71.15
1024x768 LCD
Windows 7 SP1

-- 
Bill
Gateway M465e ('06 era) - Thunderbird v14
Centrino Core2 Duo T7400 2.16 GHz - 4GB - Windows 7 SP1

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