On 28/4/02 6:47 pm, "mindspring" <[EMAIL PROTECTED]> wrote:
> Hi, a local school is looking for free tech work: I'll bite. Got a Rev. A > imac. Looking a bit rough. Problem: push power button = click sound like the > CRT is firin' up but no visual and sounds like hard drive is engaging, after > 2 seconds machine turns off completely. Tried: switching keyboards, mice, > usb port, reseat all cables, reset PRAM....still no complete boot and no > visual. Ideas anyone? raino > The iMac is dieing as the monitor section usually fires up. This points to an analog board fault. From experience this is usually caused by the flyback transformer. In cases such as this when the fault is solid you can usually confirm with a simple test using a DVM. Strip the iMac - single screw in base, pull away, then remove 2 recessed screws on each side underneath that go up into the sides of the rear case. Push in 2 serated clips and prise off speaker grill. Remove 2 screws now exposed under CRT face, then 2 screws under grey covers on top. Prise front away and remove rear case. It really is simple when you've done a few, stripping down including the metal shield now takes me 4 minutes. Ensure iMac is unplugged, then discharge under EHT cap to common. Remove EHT cap from CRT and measure from caps metal clip to common with a DVM set to measure resistance. It should read infinity, but when faulty often reads around 80K. Flybacks that make an arcing noise then cause a shutdown will often read OK doing this test, but swapping out proves them faulty. The flyback transformer can be replaced and screen/focus adjusted, or an exchange analog board fitted. Note there are 2 types of analog board, and the display adjustment utility needs to be run if you go down that route. This type of problem accounts for nearly all the hardware faults I see on the tray loading iMacs, otherwise they are very reliable. Steve Bell -- The iMac List is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | - Epson Stylus Color 580 Printers - new at $69 | & CDRWs on Sale! | SPECIAL LIST PRICES - Apple iMac CDROMs from $79.99, iMac DVD CDROMs from $99.99 3 port USB Hub $14.99, 40GB Hard Drive Upgrades $119 <mailto:[EMAIL PROTECTED]> Support Low End Mac <http://lowendmac.com/lists/support.html> iMac List info: <http://lowendmac.com/imac/list.shtml> Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/imac-list%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
