[cctalk] Re: RDI BriteLite IPX keeps going to white screen
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 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 >> 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 * ckai...@floodgap.com >> -- I thought his Markov chain needed oiling. -- Mark J. Blair >> - >>
[cctalk] Re: RDI BriteLite IPX keeps going to white screen
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 > 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 * ckai...@floodgap.com > -- I thought his Markov chain needed oiling. -- Mark J. Blair > - >
[cctalk] Re: RDI BriteLite IPX keeps going to white screen
> 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 * ckai...@floodgap.com -- I thought his Markov chain needed oiling. -- Mark J. Blair -
[cctalk] Re: RDI BriteLite IPX keeps going to white screen
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 > 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 * ckai...@floodgap.com > -- A penny saved is stupid. > --- >
[cctalk] Re: RDI BriteLite IPX keeps going to white screen
> 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 * ckai...@floodgap.com -- A penny saved is stupid. ---
[cctalk] Re: RDI BriteLite IPX keeps going to white screen
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 > 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 * ckai...@floodgap.com >> -- Fish will never understand fear of deep water. -- Tanner Greer >> - >>
[cctalk] Re: RDI BriteLite IPX keeps going to white screen
> > 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 * ckai...@floodgap.com > -- Fish will never understand fear of deep water. -- Tanner Greer > - >
