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Please post a bigger picture of your Q700 board here and we'll try to find the CUDA chip on it. If your board does have CUDA, it should have the PRAM battery as well. It's a small, 1/2 AA size lithium 3,6V battery. CUDA MCU is usually located near that battery... Everything correct. CUDA is a...

If there even was a hardware possibility to address 256 SIMMs in PM 6100, you'll still need to overcome the software limit of 128MB! I can say it with a high degree of certainty because I performed an excessive analysis of the firmware in the past as part of the MAME emulation project. When the...

To be honest, I doubt these boards will work longer than 10 years. Looking at the quickly progressing corrosion of my two PM 6100 logic boards, I'm sure they will start to fail here and there and I won't be able to prevent that. Let's think about a memory slot for a minute - if such a slot...

Can those modern SMD caps be used as replacement for the old ones? Why do other people prefer tantalum caps instead?

Probably yes. You need to break large files into smaller pieces and use several 1.44 MB disks to transfer them to your Mac or find another solution (Floppy Emu, network transfer)...

IIRC, tantalum caps need to be properly derated, i.e. a 47µf, 16V need to be replaced with a 47µf, 35V tantalum cap. For further details, see this thread.

I know this might be a stupid question but I assume you're connecting your drive to the both machines using the same ribbon cable. It works on one but not the other, right?

Oops! It looks like I've posted a link to the wrong page. Sorry! This link shows a pin diagram for the IDC 20 male connector.

That's quite possible - the board still contains eleven ancient SMD caps, three of them are located near the FDD connector. I'll try to replace these three caps first. What's the best replacement for them? All electrolytic caps are 47µF, 16V. Various Internet sources advocate the use of...

My floppy drive is actually fine! I just tested it with another PowerMac 6100 board. ;D The funniest part about it is that the drive works after it has been completely disassembled and then reassembled. No alignment or tuning was ever necessary! Well, I put some markings on the stepper motor...

Hi folks, and now comes the funny part [ :) ] Today I received another PowerMac 6100 logic board to play with. I attached my supposedly faulty floppy drive to it and ...... trara! The drive works! That's good news! > :( The funniest part about it is that the drive works after it has been...

I'd also check the voltages on the drive board for sure, both +5V and +12V rails. It should be definitely done under load, i.e. the drive need to be connected to the logic board. For pin position and numbering, you can refer to this page. +5V rail -- pin 11 +12V rail -- pins 13,15,17 and 19...

I agree with you that this kind of measure is very coarse. Anyway, it's one of those quick troubleshooting techniques helping to rule out reasonably simple issues like missing contacts or shorted traces. Any other issues would require attaching an oscilloscope to the board and do a complex logic...

You sure seem to know what you're talking about. It's a good thing to have an expert right here in the forum. According to Larry Pina's book "The Dead Mac Scrolls", the track 0 sensor should be properly aligned, too. Otherwise, the drive won't be able to format disks. It's indeed quite easy to...

When you own another Mac SE you could try to compare the resistance of each FDD connector pin to the ground between the good and the faulty boards. If you multimeter has a diode test mode: red probe on ground, black probe on each pin of the FDD connector joints. Otherwise, test in resistance...

What happens when you tell the Finder to format the disk? Does the formatting work?

Would you kindly describe (again) as detailed as possible what happens when you insert a disk in the internal drive?

After some investigation, I was able to collect some information on the track 0 sensor of the MPF75W drive: In my drive, it is an Omron optocoupler, probably a custom one because it has a non-standard, fairy long bracket for mounting onto the drive chassis. It has three wires: the brown wire...

Thank you very much for all your great advices! They helped a lot! That's exactly that what I'm going to do next. Although I suspect a failure of an electronic component I'd like to get sure that the mechanical part is good. There are three motors actually: one for ejecting the floppy one...

Removing this unit will cause alignment issues. You'd have to recalibrate the mechanics. Anyway, we have to test the sensor in order to ensure it works as expected. Give me some time for investigation...