On 2 Dec 2004 at 19:43, Jim Scott wrote: > Just picked up a G3/233 AIO basket case from a local school. It had been > scavenged for parts, so I installed known good SDRAM, I/O card, CD-ROM, ZIP > drive, floppy, hard drive, voltage regulator, and a new PRAM battery. > > I was told it wouldn't boot, but that the video was good. The school's tech > didn't know why it wouldn't boot, but said it had been running OK when it > failed. > > After putting all the drives in it, I reset the logic board, zapped PRAM, > leaned on the CUDA, slid the tray inside, plugged it in, crossed my fingers > and pushed the "I" side of the power switch down. No sound. No "booomp" that > indicates power has been turned on. > > Then I pressed the keyboard power switch. No startup chime, but the hard > drive reacted with normal startup sounds, the cooling fan began running, and > the OS 9.1 boot CD I had put in the CD-ROM tray began spinning up and making > boot-up sounds after the hard drive stopped making noise. The green power > light came on. The screen went from black to a light shade of grey in the > image area, but there were no flashes or any other signs of the CRT being > powered on. > > Immediately after that I began hearing clicking from the area of the power > supply, analog and video boards. Then the distinct odor of electronics > overheating made me decide to quickly shut off the power while the CD was > still booting. The overheat odor was reminiscent of Lysol, believe it or > not. > > After removing the case and the CRT EFI shield, I knew no one had ever used > Lysol inside as it was very, very dusty. Upon close inspection of the power > supply, analog and video boards, the only sign of overheating was on the > analog board. On the back or outside, there was evidence of > overheating/light scorching and melted shellac (?) around every pin where > the flyback transformer was soldered to the analog board. > > After cleaning out the dust, I put everything back together. But first, I > followed all the tips in the Apple service manual -- reseating ROM, > reseating SDRAM, reseating the I/O card, etc. > > On the second power-up, there was no scorching odor, so I spent a couple of > minutes listening to the clicking pattern. It sounded as if one click came > from the power supply, then another click from the analog board, then a > third click from the video board, then the cycle repeated. The clicking > sounded very much like what usually is heard when a Mac boots and a video > signal is sent to the monitor, except that instead of one click there was a > repetitive cycle of clicks. > > My diagnosis is a bad analog board with a dead/dying flyback transformer. In > which case, I'm in the market for a known good one. But as this is my first > G3 AIO experience, I'm very likely wrong and it's a bad logic/mother board. > Anyone got any ideas? Should I try replacing the motherboard with one out of > a G3/233 desktop? Thanks in advance. > > -- Jim >
Just a bit of advice from an old TV tech Jim, try resoldering the pins on the flyback before you count it out. Those pins are notorious for cold solder joints. As for the rest, best course of action is substituting a known good component if you could borrow one from someone on the list or other. Troubleshooting a logic board or video card for that matter is certainly possible, but much easier if you know for sure there is a problem with the component. Once you have determined the board is the culprit, without schematics you are mostly limited to replacing obviously damaged items such as the ones you mentioned. Just a message from Doug... -- G-List is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- We have Apple Refurbished Monitors in stock! | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> G-List list info: <http://lowendmac.com/lists/g-list.shtml> --> AOL users, remove "mailto:"; 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/g-list%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
