Member Avatar for Baldy

My wifes IMAC g4 700 video has gone to three bands of white or light grey on the 15 inch screen. What caused this and how can I fix it?

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A short, safe checklist to narrow down what "" is seeing: three pale bands across the 15" iMac G4 can come from a few different places. and are right that this is most likely a hardware problem; the items below show how to tell which part is at fault without diving straight into a teardown.

First, watch what happens during power-on. If the stripes are visible on the very first boot screens (firmware/boot logo) they are almost certainly hardware. Next, do a simple screenshot test: press Command-Shift-3 to capture the whole screen, then view that image on another machine. If the saved image shows the bands, the fault is upstream of the display (video/logic board or GPU). If the saved image is clean but the actual screen still shows bands, the panel or its controller/backlight circuitry is at fault.

A couple of quick, noninvasive checks help confirm that: in a dark room, angle a bright flashlight across the glass while the machine is on. If you can clearly see the correct image beneath the bright bands, the backlight/inverter side is implicated; if parts of the image themselves are distorted or missing, the panel electronics or video output are likely corrupted. If your iMac supports an external monitor output, testing with an external display will also separate screen hardware from logic-board-level problems.

If diagnostics point to the panel or backlight, replacement parts are usually available but can be costly relative to the value of an older iMac G4. If the screenshot shows corruption, the logic board or GPU-level repair is needed. Back up data before any service, compare part/repair cost versus buying a working used unit, and pick a repair guide or shop experienced with vintage iMac hardware if proceeding.

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Member Avatar for John A

Perhaps there's a loose cable, or maybe the screen is dying. If you're feeling handy, get out a screwdriver (non-magnetic!), and follow the instructions in the Apple manual to open up the iMac. Try wiggling some cables and make sure nothing's amiss.

Other than that, I'd say bring it to a computer technician and let them work on it.

Hope this helps

Member Avatar for Junyah

Be Careful for the Discharge on the tube...Zapp . Rattle, Rattle .. Nothing like the discharge from beeg capacitors, coils or ....monitors!

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