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@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 * ckai...@floodgap.com >> -- Fish will never understand fear of deep water. -- Tanner Greer >> ------------- >>
