Powerbook 540c screen problem

[Dimitris1980]

I got from a friend a powerbook 540c. He didn't know if it works because he hadn't power adapter and batteries. I bought a power adapter and two intelligent batteries which i connected them to the powerbook. I turned it on and it worked. It has Mac Os 8.1 installed and 36 mb ram. I left it turned on for a while because i had something to do. When i came back i saw that the screen became white. I can hear the hard disk working so i pressed the power button and i restarted the powerbook but nothing changed. Just white screen. What can i do?

[beachycove]

Some idle thoughts:

1. You have tried fiddling with the brightness button, etc.?
2. You could confirm that the vram and graphics circuitry on the logic board are working by attaching an external display (assuming you have the requisite adapter).
3. The usual advice in cases of LCD malfunction is to disconnect and reconnect all ribbons, so as to make fresh connections. However, there are new suggestions cropping up here and there these days that many of the problems in vintage LCDs relate to failed electrolytic capacitors. I cannot off the top of my head recall how many capacitors appear when the 540c LCD is taken apart (I have done it now a couple of times), but I do recall that there is a lot more in there than just the screen itself.

The simplest thing would, of course, be to source a replacement LCD — or to take the parts move in the other direction by parting this unit out, selling the 36MB chip and the SCSI drive and buying a whole new 540c with the probable proceeeds. I'd try 1-3 myself, as I tend to think that parting out collectable machines that can easily be fixed is a mistake.

[Dimitris1980]

I don't have adapter for connecting the powerbook with an external display. Yesterday evening i turned it on and it worked normally. Today it shows again just a white screen.

[mcdermd]

I had the same behavior in a PowerBook 140c and it turned out to be bad capacitors in the display. Replacing them cleared up the issue.

[Dimitris1980]

How can i do that and how and where can i look for powerbook 540c capacitors?

[techknight]

Ive seen this happen all too commonly, mainly in the 5300c series. there is a small microfuse on the display panel, replace it. If it pops again, you have a shorted buffer or DC-DC converter in the panel that provides the scan voltage.

[Dimitris1980]

Where exactly is that small microfuse?

[techknight]

its been several years since ive had a PB540 screen apart, its hard to say. But they are usually right near where the cable plugs into the panel. its a small SMD fuse. usually a white ceramic lookin guy. it has a component label something like "F1"

[Dimitris1980]

I disassembled the display panel, the cables and then i connected them again but nothing. Also i found a cable and i connected the Powerbook to an external display but nothing on the screen except the background theme.