Classic won't boot

[notcrazy_iminsane]

This problem just started the other day :O

After many failed attempts to network my Classic to my other Macs and a disassemble to clean the floppy drive, the Classic doesn't want to boot. It'll turn on, chime, then stay on a grey screen with the cursor. I can move the cursor around, but that's it! I've let it run for 30 minutes on that screen, and nothing happened. No ? floppy, no nothing. I'm at a loss with trying to figure out how to fix this problem. After I disassembled everything, I made sure to put it back in the same place and everything.

I've gotten a sad mac once, but that was because I didn't put the RAM card back in all the way after I disassembled the Mac. Any clue what might be able to fix this problem?

 

[coius]

I am wondering if the controller board on your floppy is toast. You wouldn't happen to have a spare floppy drive that you can throw on the cable could you? or replace the cable even.

I had a floppy drive (1.4MB) that I pulled from a failed SE/30 that I tried in a Macintosh Quadra for a friend to get OS 7 on it. When the SE/30 died, it was from a surge and it fried practically everything in it, including the controller board on the floppy. So the floppy responds with erratic commands, the Mac was waiting and it did the exact thing.

Check the floppy controller board for burnt IC chips, and verify it works on another machine. Failing that, swap with another cable/floppy drive and see.

pretty sure it's the floppy drive and/or cable.

 

[mcdermd]

Couldn't you test if its the floppy by unplugging the drive and booting from the Classic's ROM disk?

 

[notcrazy_iminsane]

The floppy drive never worked for me. It would sound like it was trying to read/write, but just couldn't. It detects floppies, says they're unrecognized then try to format/initialize. After it was done, it would say it failed and eject the floppy. I'll unplug the floppy and try booting from the ROM as soon as I get home and see if that does any good.

 

[phreakout]

You say it gives you a light gray screen with the mouse cursor, but won't go any further? I don't know if this can be similar for the classic line, but on an SE/30, that same symptom means that the SCSI controller chip is bad and needs to be replaced. Either that or maybe some of the Network Resistors (labeled "RPx"; x= a number) wired to the SCSI controller chip need replacing as well.

If I remember correctly, a lot of retro Macs used that chip. It should be labeled as "53C80", with either NCR, Zilog or AMD as the manufacturers. All I can say is good luck, when it comes to replacing that chip. You would need to have a specialized desoldering station in order to properly change out the part. The Network Resistors shouldn't bee that bad, since they may still be lead-through-board type components.

To verify if it's bad, simply disconnect ALL SCSI devices internally and externally from the Classic. Restart the system and try booting off of floppies or boot off of the ROM (only works on the Classic I, not the Classic II or Color Classics). Apple + Option + X + O held down at restart will boot from the ROM. There is a copy of System 6.0.8 burned into the Mac's ROM. Don't hold it down too long or it will ask if you want to rebuild the desktop. Click cancel to stop that. If your Classic boots after doing all this, then you'll know the SCSI controller chip is in fact bad. A permanent fix is either replacing the chip or getting a replacement Classic I logic board.

73s de Phreakout. :rambo:

 

[notcrazy_iminsane]

I haven't gotten around to testing it just yet. I should try doing that when I get home.

If it turns out it's the chip, then I'll either find someone who can replace it and recap the board or just invest in a new board entirely. I was hoping it would be a simple fix since I have never done any soldering work before

 

[phreakout]

I'm currently trying to replace that very chip (53C80) for another 68kmla member. I'll tell you this much from experience: I think this will be the last request for replacing those types of chips for now. I don't have the right tools to get the job done properly. I'll need an air rework station for soldering/desoldering and the square iron tips for these chips. The technical name for these kind of chips are PLCC, which stands for Program Logic Control Chip. The iron tips are designed to get underneath the folded legs (contacts) and desolder all sides at the same time, allowing you to lift the part away without damaging the traces or legs of the chip.

So when I get this one done, it will be the last one I attempt (successfully or not) to replace the chips on. Better off getting someone else to do it for you who has the right tools or just replace the logic board and be done with it.

73s de Phreakout. :rambo:

 

[techknight]

Use some heat-tape and cover all areas of the mainboard, exposing ONLY the IC for removal. Using a kitchen pancake/food griddle, preheat the board to 275 for about 10 minutes.

Remove IC with heat gun. Buy some tin/lead solder paste, like Zephaste.

Turn off griddle, let board cool down

Wick up all solder from board after IC removal. Take the solder paste and apply a thin bead across all IC pads on the board. And i mean a THIIIN bead. you dont want too much, as it will bridge and short during a reflow, you dont want too little either or some pins may not connect

Place the chip into place. then use a small nozzle fitting to heat gun, and carefully go around the IC with the hot air nozzle. the paste will melt and reflow new solder on the IC

a reflow/rework station is about $132 bucks on ebay right now. Yellow faced, VFD display, etc...