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flyingfadr
01-02-2004, 07:13 PM
Hello,

I just purchased a G4 DP450 128MB/20GB that would not power on......thinking and HOPING it would be something simple.... after checking the battery, reaseating the SDRAMM, reseating the processors, reseating the video card resetting the processor switch, and REPLACING the power supply, it STILL will not power up ( no sound, no fans spinning, no drive spin-up, no LED's...zip, zilch, nada...).
How can i tell whether it is a dead logic board or a dead Dual Processor module ?? Any tests that can be done ?? If the logic board is ok but the Processor Card is bad, wouldn't it at least make a chime of death ?

Thanks in advance !!!!

Cojomisa
01-02-2004, 08:12 PM
Just curious if you have a keyboard with a Power Button or if you are only pressing the button on the front of the G4.

I have seen the Front Panel Control Board go bad before, so it could be this simple. However a failure to start up is typically the CPU Module. Since you are not seeing any lights at all (even for 1/2 second?) out of the Power Button on the Front Panel, that may be all it is. Very simple to replace, but the cost of the module is kind of steep.

Let us know if you have keyboard power-on capability or not.

John

flyingfadr
01-02-2004, 09:39 PM
No, i do not have a keyboard with the power on key..... i had thought about the front switch being bad....maybe i'll go pick up a Kensington keyboard that has one... they're only $29. No, there are NO lights at all....not even for a split second... no fan movement... nothing happens....
Any telltale signs of when either the Processor card or the Logic board is bad ?.... ways to differentiate between one or the other being dead ( since i dont have the ability to swap parts...)

Thanks in advance for your input !!

ricks
01-02-2004, 11:24 PM
?The G4 Service Manual is on my iDisk. You are welcome to download it and see if there are some tips as to determining what is happening. G4 Manual (http://homepage.mac.com/rstephens/.Public/G4Manual.pdf.sit) It's big, 10 MB, so it'll take a little time to download.

Rick

Quis Custodiet Custodes Ipsos?

Cojomisa
01-03-2004, 12:26 PM
Symptoms are not too hard;

1) No Power indication;
No lights on any component when button is pressed.
-Power Supply
-Front Panel Board
-Power Cord or socket

2) Logic Board
Everything seems to come on, but nothing happens. Can get a Startup Chord sometimes, which confuses the situation. May get blinking "?", but probably won't get anything on Screen since the I/O isn't working.

3) CPU Module
Similar to #2, although no Startup Chord. Must have a Good CPU to generate that output.

If the Power Supply is Known Good, but you do not get at least 1/2 second on the Power Button light after pressing it, then the Front Panel Board is probably the problem. The Power Button will light up even though 2 & 3 are dead.

Let us know what happens.

John

flyingfadr
01-04-2004, 05:43 PM
Hello all,

Just wanted to let you know that I found the culprit ... THANKS TO JOHN (cojomisa) !! It ended up that the Front Panel Board on the the unit was bad !!.... went to CUSA, and picked up a Kensington Keyboard-in-a-Box for $29 plugged it in, and POWERED RIGHT UP !!!! HUGE load off my shoulders !!

Thanks for all your help and ideas !!... You guys http://forums.macgurus.com/images/kickass.gif

Mark

Cojomisa
01-04-2004, 06:06 PM
Mark,

Am happy to know you got it back up and running that easily. Glad to have been of some use. We all appreciate the feedback.

John