thank you Jim, I will try to replace the LVDS cable. I will keep you and others updated. regards, Carlo
On Aug 31, 7:23 pm, Jim Scott <jesco...@gmail.com> wrote: > > On Aug 26, 7:07 pm, Jim Scott <jesco...@gmail.com> wrote: > >> On Aug 23, 2010, at 11:27 AM, pink74slk wrote: > > >>> I have an iMac G4 USB2.0 and the monitor does not lit anymore. > >>> I replaced the inverter and still the same black monitor. > >>> I then have bought the cable VGA adapter and connect the iMac to my > >>> TV, and here the facts: > > >>> just keep in mind that after the backup I did, I formatted the HDD > > >>> so > > >>> if turn on the iMac, the TV will be black as well, no signal > >>> transmitter > > >>> instead > > >>> starting up the iMac from the boot DVD Leopard, the TV monitor is > >>> white. > > >> Carlo, > > >> A white screen means that the screen is getting power, and that your > >> inverter is OK. However, your screen is not getting data, which means that > >> there's a problem in the circuit from your logic board video cable > >> connector to the LCD. The most likely problem is that the video cable is > >> not properly connected to the logic board, or to the LCD, or both. > >> However, if the cable is securely connected to the logic board and the > >> LCD, the next most likely problem is a break in the video cable (also > >> known as the LVDS or low voltage data signal cable) between the logic > >> board and the LCD connector. Because of the way the cable is snaked > >> through the iMac G4's neck, which can flex and swivel, this is a common > >> occurrence. > > >> The fix is to replace the neck with a new one. If you do this, make > >> certain you get an exact replacement. There were a bunch of different > >> necks for the iMac G4, depending on screen size and logic board/cpu > >> version, so be careful. Just any old iMac G4 neck may not work. There's a > >> tag on the cable, which will require an Apple Service Manual to decode, > >> that identifies the neck in your machine. It's on the logic board end. > >> Match the code on that tag, and you've got the right neck. > > >> Aren't iMac G4s such sweethearts to work on? No wonder Apple moved on to > >> the current cantilever pedestal AIO flat panel form factor rather quickly. > > >> Jim Scott > > On Aug 29, 2010, at 6:36 AM, pink74slk wrote: > > > Thank you Jim, > > > please correct me if I did not understand your explanation. > > The LCD monitor of my iMac G4 never turns white, it always remain > > black since the failure happened. > > The only "white signal" is on the TV screen, when booting up from DVD > > Leopard, and the LCD it is slightly black. > > > Any more insights, or what you told me earlier is still applicable? > > thank to you and everyone is contributing/commenting. > > > regards, Carlo > > Carlo, > > Let me try again. A white screen with no data almost always means the > inverter is getting power and illuminates the screen. No data on the screen > means the data signal cable isn't working -- it's broken internally or > disconnected or not connected properly. > > From your description, you've got a problem with the low voltage data signal > cable not delivering data to the built-in LCD of your iMac G4. I suspect the > cable is broken or shorted inside the neck. But it could be disconnected or > not connected probably to the logic board, or to the LCD itself. There also > could be a problem with the inverter cable. Have you tried shining a very > bright light on the screen after the iMac has booted? If you can see any > images -- even faintly -- that means the inverter cable has broken/shorted, > probably inside the neck > > As for your connection to the TV, it's clear that power is getting to the > screen, which is why it turns white. But the video signal or data isn't > getting there. This could be because there's a problem with the video > circuitry on your iMac's logic board, or a problem with the adapter cable or > video out port, or because the video cable to the LCD in the iMac is shorting > out the video circuitry. Or it could be a simple incompatibility between the > iMac and the TV (and you don't say what kind of TV -- flat screen or tube). > > Try connecting the video out port to a regular VGA computer monitor instead > of your TV. Borrow one if need be. If you can't get video on the monitor, > then disconnect the video cable to the LCD from the logic board, which will > require some disassembly/reassembly of the iMac. I've had situations where > disconnecting the video cable from the logic board made the external monitor > work, so it's worth a try. > > If after all of this you still cannot get a video signal on the external > monitor, then you may have a bad iMac logic board. However, based on the fact > your TV screen does go white, I suspect that your logic board/video circuitry > is OK and that connecting to a standard VGA monitor will work, which means > the no-video problem with the LCD is from the logic board end of the video > cable to the LCD itself. > > Hope this helps. It's a bear trying to diagnose this way, but I've given it a > try. > > Jim -- You received this message because you are a member of the iMac Group, a group for those using Apple iMacs and eMacs. The list FAQ is at http://lowendmac.com/imac/list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to imaclist@googlegroups.com To leave this group, send email to imaclist+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/imaclist
