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 Post subject: Replacing power board revived Pismo, but only for a day
PostPosted: Tue Jan 06, 2009 10:02 pm 
Executive summary: Pismo with occaisionaly video problems died. Buzz from track pad area made me think a power board would solve the problem. I installed a power board, and it seemed to work for a few hours, but then the symptons from before the death began reoccurring and now the Pismo just makes a faint high pitched noise when the power button is pressed.

Two years ago my Pismo was acting badly. The video display would occasionally lose a color (the whites would turn pink, and other colors would go odd--the display cable was fine) Moving the display solved the problem. On rare occasions the screen would go black and the computer would crash. Disconnecting the power and battery, and pressing the reset button on the back would allow the computer to restart. Then eventually it died, and it started making a faint, but clearly audible high pitched whine. Pressing down on the case directly between the keyboard and the track pad would let the computer start, but once pressure was released the power would cut out. I decided it was time to get a new MBP. Fast forward to now...

I've always missed my Pismo. In addition to an unreasonable emotional attachment to a piece of black plastic, it was good to have an OS 9/OS X bootable machine around. I plugged it in and the buzz seemed to come from the power board under the trackpad, so I bought one and installed it. I was very excited when I plugged it in and was greeted with a blinking question mark (the drive had been used as a back up drive, and wasn't bootable). Strangly, I couldn't get the computer using the OS 9.0.4 disk that shipped with the Pismo (I think this was due to a firmware update), then I couldn't get the computer to boot using the OS 9.2.1 disk. 10.2 didn't work, but 10.3 did! I was on my way, so I thought.

After 10.3 installed, the computer screen went black during the setup process. Pulling the plug, the battery, and pressing the reset button got the computer to start up. Strangely though, the computer reported that it only had 128 MB of RAM installed. I opened the computer, reseated the RAM, restarted it, and the computer reported the correct amount of RAM. So, I went about installing software, and at one point the whites went pink. I adjusted the screen and kept going. Things only got worse. After each crash or failed start up (I tried a variety of startup disks that apparently weren't designed to start up a Pismo) the computer reported it was missing 512 MB RAM. During one crash I noticed faint horizontal lines dancing across the screen.

Anyway, the computer won't boot now. It makes a faint high pitched noise, and I'm beginning to think that there's more than just one problem with this old Pismo. I'd really like to get it going, but I don't want to spend much to get it fixed. Any ideas?


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 Post subject: Re: Replacing power board revived Pismo, but only for a day
PostPosted: Tue Jan 06, 2009 11:00 pm 
Replying to my own post... bad form I know...

I'm typing this from my Pismo. I plugged it in, pressed the power button and got a faint high pitched noise. I pulled the plug, pressed the reset button, and, on a whim, applied pressure to the case between the keyboard and the track pad. To my amazement, the computer started. The light blue on the standard detop picture was weird, and moving the diplay restored the normal color scheme. When I stopped applying presure to the computer, I was amazed that it kept working. (Perhaps applying pressure had nothing to due with it).


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 Post subject: Re: Replacing power board revived Pismo, but only for a day
PostPosted: Wed Jan 07, 2009 9:45 pm 
OK, so it started up last night. It crached shortly after making the post. Backlight went off, pattern across the screen for about 15 seconds and then nothing. After unplugging the comoputer and pressing the reset button it started up. So this morning I erased the 10.3 install, installed 9.2.1 (I forgot to install the OS 9 disk drivers when I installed 10.3), updated the OS 9 Airport software, Installed 10.3 and did a bunch of other stuff. The computer ran all day. The screen changed colors once when it was closed and reopened, a small adjustment to the display resolved the problem and everything worked until just a couple of minutes ago. It went black while browsing this forum. Unplugging the computer and hitting the reset button worked, but very soon after the restart it crashed again. This time however, pulling the power and hitting the reset button didn't work. I tried it at least three times. On a lark, I pressed down on the case between the keyboard and tackpad and turned the computer on, it began to boot, Unfortunately, when stopped applying pressure, the computer went down in its usual way, but when I reapplied pressure, and image of the startup apple appeared. Since the booting process didn't continue, I turned off the computer by holding the power button. When I pressed the power button again, it started up, and I'm using it right now.

It's and interesting problem that I'd love to solve... but I'm totally out of my league here.

Chris


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 Post subject: Re: Replacing power board revived Pismo, but only for a day
PostPosted: Thu Jan 08, 2009 10:32 am 
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Site Admin

Joined: Thu Feb 27, 2003 6:35 am
Posts: 977
Well the PMU board is where you are applying pressure, so it could be defective or not getting good contact inside the machine.

Other than that, the problems themselves sound more like a logic board issue.


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