I am the killer of 540c screens ?!?!

[srieck]

After putting in a second screen, I cranked up the controls on the front panel and the screen lasted maybe 5 minutes...dead to an all white screen after a reboot...this was the same issue with the first screen. So I think some problem on the motherboard or inverter board is killing these lcd's ? Has anyone seen this? These Toshiba screens are getting rare and not cheap.

On the first one, I disassembled the computer down to the motherboard and the screen seemed to momentarily come back. So I know that sounds like a loose cable but it's hard to believe because this seems to be initiated by cranking up the contrast and brightness to max...then it's just permanently white.

 

[srieck]

Also - I put in my b&w LCD from my 540(nonC) to see what happens...it doesn't blow this LCD...runs fine but of

course I want to get a color screen in there that's working.

 

[techknight]

probably popped another fuse on the display panel again. and they dont "blow" without a reason. probably leaky electrolytics causing higher current consumption, thus popping the main B+ fuse to the panel.

 

[srieck]

Interesting - all the caps look perfect visually but I know that isn't conclusive. Is this more likely a motherboard or invertor board issue? Is there anyway to know?

 

[srieck]

...and is it possible to (and would there be any risk) in just bypassing this fuse?

 

[techknight]

worst you can do is kill the screen, but hte screen is already dead so whats the point? no harm.

 

[srieck]

Where would I locate the main B+ fuse you're referring to?

 

[techknight]

usually very close to the connector at which the video cable plugs in. itll be a surface mount white, or something of the like. usually labeled F1 or etc.

i dont have that particular screen in front of me, so i cannot remember.

 

[srieck]

Ah yes...I got it...gonna just bypass it and see what happens.

 

[srieck]

Amazing...that fixed it! At least for the time being...thanks very much for your help!

 

[techknight]

i figured it would. ive messed with enough of the screens to build a wall out of them.

 

[srieck]

Worked for awhile....but now I'm back to a white screen. I realize jumping fuses is fixing the symptom and not the problem so I'm wondering how likely it is that the caps are the issue as you mentioned? What would be blowing next on the LCD after the jumped fuse?

 

[srieck]

Also - whatever blew most recently, it seems to have rendered the contact adjustment inoperable. Brightness works fine. Not sure if that's any clue?

I noticed something Labeled FU1 on the inverter board which I assume is also a fuse?

 

[srieck]

"contrast" adjustment not "contact" adjustment. (iPhone autospell)

 

[srieck]

Nevermind - seems to be a flaky ribbon cable from the connector board to the LCD board

 

[BTeam]

The 540c was set up to use at least four different manufacturers displays. Each with its own ribbon cable. It is important to match the display to the correct ribbon cable.