Floppy drive Sony MP-F51W-23 upper head doesn't touch the disk

[billbucks]

Hi,
I found a replacement floppy drive for my Mac SE 30. It's a Sony MP-F51W-23 (MFD-51W-03) on the side that I took from a dead Mac.
Using the cable with the red stripe, the drive loads and ejects disks ok but all disks are unreadable. I noticed the upper head didn't touch the floppy disk (running the Mac SE opened) so I gently pushed with my finger on the head and then it worked fine ! The head is about 2 to 3 mm to high.
I'm not sure what to do as I don't want to break this fragile part of the drive by trying to bent it.

I suspect the head to stay like this because the drive has been left unused with no disk inserted for long which made the upper head unable to bend down as what it was. Is there a way to fix this ?

 

[JDW]

I strongly recommend a teardown so you can shoot photos for us of the head, both in the open-wide condition, and when clamping a disk. That would give you a better look too. Because if something is indeed bent, it's very hard to bend it back to the factory condition.

 

[billbucks]

Thanks, I found a tutorial to dissassemble it

 

[patters]

If I recall correctly, during the disassembly there is a sort of sliding plastic piece that kind of raises up the head like this in order that you may get some other part out without wrecking the head. So if you're lucky, this may be the cause and perhaps there is no actual damage.

 

[JDW]

there is a sort of sliding plastic piece that kind of raises up the head

I believe you’re referring to the black plastic piece that I am touching with my index finger in the photo below.

 

[patters]

The very same, yes. From what I remember, it's possible to reassemble the drive and leave this in the wrong position.

 

[JDW]

If left off completely or if installed upside-down (such that it us UNDER the metal frame rather than on top of it), then yes, the heads would remain slammed against each other instead of "open" when no disk is in the drive. So, yes, that black piece is a critically important part.

@billbucks , how did your disassemble go?

 

[billbucks]

@JDW I followed the tutorial which went well until I connected the floppy drive to my Mac SE 30.
It made a strange noise so I unplugged the drive as it wasn't properly mounted. The issue is that I smelt some burn around the Mac power supply or on the little card plugged at the back of the CRT.
Testing the PSU, I get the 12V and 5V output with a multimeter so it seems ok.
On the motherboard I noticed a tiny crack on the UJ11 VLSI chip but I'm not sure if it was there already. UE10 looks also a bit weird.
I tried once to start the Mac again and not much happened (black screen) so I'm looking for a solution.

It read that I need to look at recaping the analog board and maybe the power supply (Sony model). What do you think ?
Is there something I need to look on other cards such as the one at the back on the CRT ?

I put some photos.

 

[JDW]

I'm afraid I cannot identify the crack in your uj11.png photo, and other than being a but dirty, I don't see anything unusual in you ue10.png photo either. But neither photo is high resolution or tack sharp, so I guess my eyes are not seeing what your eyes are seeing.

Now as to the dark spots on the yellow flyback transformer glue and the dark spots on the circular ceramic disk caps on the CRT Yoke board, I cannot tell if that is just an accumulation of dirt or a burn mark. If you can remember or if you had photos prior to smelling something burning, that would be very telling.

If you have a cracked IC on the motherboard, I doubt your Mac would boot. And the cause of the crack would be a short of some kind or excessive current draw through the said chip. In other words, I don't see that as having anything to do with an unrecapped power supply or analog board.

And while you seem to be getting 5v and 12v, the question is, how stable is that? A multimeter may not tell you that. An oscilloscope would, but you probably lack that. But usually the best way to identify your PSU condition is to remove it, then open the metal chassis and pull the circuit board out and examine if there are dark splotches and/or spilled fluid on the PCB, in which case you absolutely have PSU issues and the board must be cleaned and all the electrolytic capacitors changed. That is actually more important than the Analog board, even though it's good to recap that too.

But in the end, if you have cracked chips or an otherwise bad SE/30 motherboard, then having a non-booting Mac is expected. But are you saying the chip wasn't cracked before your floppy drive install? Did the SE/30 board work fine prior to your floppy drive install? Your opening post seems to indicate your machine was at least somewhat functional. But normally a floppy drive swap should not cause smoke and a smell, and should not crack chips on the motherboard, even if the drive was damaged. I suppose anything is possible if the circuit board controller on the floppy drive was fried, but I've never seen that before.

You need to examine your PSU first.
After that, you need to disconnect all floppy drives and SCSI drives and see if you can get the bare naked motherboard to bong and show a screen. If it won't do that with all drives disconnected, assuming your PSU is good, then it would seem something fried at least one chip on your motherboard, which is quite unusual. But if a chip is indeed cracked (again, I cannot see that from your photo), then such would explain a non-functioning motherboard, but as to why that chip would have fried upon a floppy drive swap is something new to me.

 

[billbucks]

Looking at an old photo of the motherboard, the crack seems to have been there before.
I can't find at the moment any photo of the CRT Yoke board but if the smell is on this board, should I change the capacitors? Note that I have a spare Mac SE (not 30) which is due to be repaired. Can I switch the yoke board to test ?

Attached are photos of the inside Sony PSU unit which looks ok.

 

[JDW]

Thank you for the photos. Unfortunately they are not high enough resolution for me to see any possible leakage, but you would really need to remove the entire PCB from its metal housing to view both top and bottom anyway. It's troublesome to do that, I know, but it really does need to be done. Here's why. It was only when I removed the PCB from a chassis in the past that I spotted a little crud around the edges...



But have a look at the bottom side of that same PCB...



And then look at what happened when I removed the caps...



And yes, I realize your PSU is a SONY and the photos I showed you are of a different model, but that doesn't matter. Inspection is very important.

The Analog Board and the Power Supply and the CRT Yoke board are all compatible and exchangeable between an SE and SE/30. The metal chassis is a tad different, and of course the branding on the front plastic is different, but if you are able to fit the SE/30 board inside your SE rig, that could be a quick test to see how the motherboard responds.

I made a this video in the past to show how to make an extension cable that allows you to attach a motherboard externally to an SE or SE/30 rig. That eliminates headaches relating to getting one motherboard to fit into a different chassis.

But we still need to figure out what happened. Can you describe the unusual sound you mentioned in your earlier post? And you said you smelled something burning, but there was no smoke at all which could identify the source of the smell?

 

[billbucks]

Thanks for the information. I ordered the capacitors from Mouser and will keep you informed of the updates.