29 Oct
2022
29 Oct
'22
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.
>
> --
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> Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
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>