29 Oct
2022
29 Oct
'22
7:54 a.m.
I've been trying to do a little work on the RDI BriteLite IPX I have here, but
when it runs more than a few minutes the LCD just blanks out white. The machine
seems to still respond to commands, so it seems like it's something with the
display hardware. Even powered off and back on it won't go back to normal until
I let it sit for awhile.
I suspect heat is part of the issue and it certainly feels warm; there are two
loud cooling fans inside, but with the case off and checking airflow the fans
do seem to be working. Having the case off doesn't make the display any happier
though. One fan is in the power supply and another fan is in the (LCD?)
inverter board. Finger-checking large chips while in operation doesn't burn the
skin.
Anyone familiar with this issue? I suppose I could look for a SPARCstation IPX
to take the motherboard out of and replace this one with it, but it seems more
like the problem is in the display, which is a custom part.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- Fish will never understand fear of deep water. -- Tanner Greer -------------
29 Oct
29 Oct
10:33 a.m.
I've been trying to do a little work on the RDI BriteLite IPX I have here, but
when it runs more than a few minutes the LCD just blanks out white. The machine
seems to still respond to commands, so it seems like it's something with the
display hardware. Even powered off and back on it won't go back to normal until
I let it sit for awhile.
I suspect heat is part of the issue and it certainly feels warm; there are two
loud cooling fans inside, but with the case off and checking airflow the fans
do seem to be working. Having the case off doesn't make the display any happier
though. One fan is in the power supply and another fan is in the (LCD?)
inverter board. Finger-checking large chips while in operation doesn't burn the
skin.
At one time it used to be possible to buy aerosol cans of "freezer" which were
supposed to help trace faults like this in televisions etc. Maybe it is still
available? I have read tales of success using it however I don't ever recall
it being any help to me. It may be that I didn't have any of the right sort
of faults.
Regards,
Peter Coghlan.
Anyone familiar with this issue? I suppose I could look for a SPARCstation IPX
to take the motherboard out of and replace this one with it, but it seems more
like the problem is in the display, which is a custom part.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- Fish will never understand fear of deep water. -- Tanner Greer -------------
5:52 p.m.
This usually means the timer of the pulse width modulation circuit is changing.
If it’s an RC type circuit, probably the resistor is heating up and changing value. If
it’s a ic that controls the PWM then check out the IC and the components that connect to
the control pin.
Sent from my iPhone
On Oct 29, 2022, at 03:48, Peter Coghlan via cctalk
<cctalk(a)classiccmp.org> wrote:
I've been trying to do a little work on the RDI BriteLite IPX I have here, but
when it runs more than a few minutes the LCD just blanks out white. The machine
seems to still respond to commands, so it seems like it's something with the
display hardware. Even powered off and back on it won't go back to normal until
I let it sit for awhile.
I suspect heat is part of the issue and it certainly feels warm; there are two
loud cooling fans inside, but with the case off and checking airflow the fans
do seem to be working. Having the case off doesn't make the display any happier
though. One fan is in the power supply and another fan is in the (LCD?)
inverter board. Finger-checking large chips while in operation doesn't burn the
skin.
At one time it used to be possible to buy aerosol cans of "freezer" which
were
supposed to help trace faults like this in televisions etc. Maybe it is still
available? I have read tales of success using it however I don't ever recall
it being any help to me. It may be that I didn't have any of the right sort
of faults.
Regards,
Peter Coghlan.
>
> Anyone familiar with this issue? I suppose I could look for a SPARCstation IPX
> to take the motherboard out of and replace this one with it, but it seems more
> like the problem is in the display, which is a custom part.
>
> --
> ------------------------------------ personal: http://www.cameronkaiser.com/ --
> Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
> -- Fish will never understand fear of deep water. -- Tanner Greer -------------
>
7:56 p.m.
This usually means the timer of the pulse width
modulation circuit is changing.
If it’s an RC type circuit, probably the resistor is heating up and changing value. If
it’s a ic that controls the PWM then check out the IC and the components that connect to
the control pin.
That's an interesting thought. It's almost certainly an IC, though I don't
know
the details of the panel (though it looks like it's off-the-shelf, not
RDI-custom). I suppose I could start with what's in the cooling airflow zone.
My worry is if I found the marginal part(s) I'm not sure how I could easily fix
it (with my luck it won't be a discrete part).
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- A penny saved is stupid. ---------------------------------------------------
8:02 p.m.
Is there any kind of brightness control? Does it work at all when the screen goes white?
Sent from my iPhone
On Oct 29, 2022, at 12:56, Cameron Kaiser via cctalk
<cctalk(a)classiccmp.org> wrote:
This usually means the timer of the pulse width modulation circuit is changing.
If it’s an RC type circuit, probably the resistor is heating up and changing value. If
it’s a ic that controls the PWM then check out the IC and the components that connect to
the control pin.
That's an interesting thought. It's almost certainly an IC, though I don't
know
the details of the panel (though it looks like it's off-the-shelf, not
RDI-custom). I suppose I could start with what's in the cooling airflow zone.
My worry is if I found the marginal part(s) I'm not sure how I could easily fix
it (with my luck it won't be a discrete part).
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- A penny saved is stupid. ---------------------------------------------------
8:05 p.m.
Is there any kind of brightness control? Does it work
at all when the screen goes white?
There are brightness and contrast controls, but they don't seem to do anything
even when the screen is working properly. (Note that this could simply be an
issue with the physical controls themselves rather than the display
controller.) Likewise, when the screen goes white, turning down the brightness
(or upping the contrast) does nothing; the screen remains blank bright white.
The CCFL backlight is unchanged and fully illuminated.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- I thought his Markov chain needed oiling. -- Mark J. Blair -----------------
8:15 p.m.
One thought is that the brightness control might be heating up and changing value. You can
check the controls easily with a ohm meter. Check ohms across the control when cold,
disconnect ohm meter and plug in the machine until it goes white. Then disconnect and
measure across the control again.
Sent from my iPhone
On Oct 29, 2022, at 13:05, Cameron Kaiser via cctalk
<cctalk(a)classiccmp.org> wrote:
Is there any kind of brightness control? Does it work at all when the screen goes white?
There are brightness and contrast controls, but they don't seem to do anything
even when the screen is working properly. (Note that this could simply be an
issue with the physical controls themselves rather than the display
controller.) Likewise, when the screen goes white, turning down the brightness
(or upping the contrast) does nothing; the screen remains blank bright white.
The CCFL backlight is unchanged and fully illuminated.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- I thought his Markov chain needed oiling. -- Mark J. Blair -----------------
8:16 p.m.
The value of the control might be marked on the board too so you could use that as a
guide.
Sent from my iPhone
On Oct 29, 2022, at 13:15, Wayne S
<wayne.sudol(a)hotmail.com> wrote:
One thought is that the brightness control might be heating up and changing value. You
can check the controls easily with a ohm meter. Check ohms across the control when cold,
disconnect ohm meter and plug in the machine until it goes white. Then disconnect and
measure across the control again.
Sent from my iPhone
> On Oct 29, 2022, at 13:05, Cameron Kaiser via cctalk <cctalk(a)classiccmp.org>
wrote:
>
>
>>
>> Is there any kind of brightness control? Does it work at all when the screen goes
white?
>
> There are brightness and contrast controls, but they don't seem to do anything
> even when the screen is working properly. (Note that this could simply be an
> issue with the physical controls themselves rather than the display
> controller.) Likewise, when the screen goes white, turning down the brightness
> (or upping the contrast) does nothing; the screen remains blank bright white.
> The CCFL backlight is unchanged and fully illuminated.
>
> --
> ------------------------------------ personal: http://www.cameronkaiser.com/ --
> Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
> -- I thought his Markov chain needed oiling. -- Mark J. Blair -----------------
>
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7 comments
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participants (3)
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Cameron Kaiser -
Peter Coghlan -
Wayne S