Mac SE 30 floppy drive head issue

[billbucks060]

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. However it identified 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 (see photo)
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. I inserted a disk and will leave it with a weight applied to see if it's going to go back to normal.

 

[bibilit]

Remove the upper carrier, maybe this is preventing the head from touching the disk.

 

[billbucks060]

If I remove the upper carrier, the floppy disk hits the head and will damageit when inserted in the drive.

 

[mitchW]

I think the main reason is the spring that loses tension after 30+ years of upwards pressure.

 

[billbucks060]

Is it worth dissassembling it as on

?

 

[bibilit]

The idea is to see if removing the upper carrier, the upper head is touching the lower one.

If so, something is preventing both to do so.

 

[jmacz]

If the previous owner of the drive lifted the head too much during cleaning, it will stretch out the spring and the head will stay too high. That video you linked I believe shows you a technique to bend it back, but sometimes it works, sometimes doesn’t if it’s too bent upwards. Good luck!

 

[ironborn65]

the pull-down string is at the back. under the upper arm, check it out.
There are 3 or 4 tents where you can adjust the pressure on the heads, I was able to recover a couple of drives in this way

 

[bibilit]

If the previous owner of the drive lifted the head too much during cleaning, it will stretch out the spring

I think the small spring is not the issue, but rather the metal plate also acting as a spring, and the chances to getting it lined up is 50%

 

[billbucks060]

the pull-down string is at the back. under the upper arm, check it out.
There are 3 or 4 tents where you can adjust the pressure on the heads, I was able to recover a couple of drives in this way

I'll try this

 

[billbucks060]

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.
Testing the PSU, I get the 12V and 5V output with a multimeter so it seems ok. I fear that something went wrong with the motherboard !
The small VLSI chip next to the speaker connector has a tiny bubble on top which I don't think it had before..

I attached some photos.

Is there anything I can try doing to check if it's the motherboard, analog board, or else?
I feel really down about the outcome

 

[Mk.558]

UE10 is the Apple sound chip.

A longer Port J12 cable should probably be something you'll want pretty soon. It means you can have the logic board out of the machine while you test things, since it's really annoying to keep pulling the motherboard in and out when you're having issues.

If the power supply has not been recapped, that should be taken care of at once. The Sony one, which is what I have, is rather annoying but not too bad. One of the capacitors, the largest one, isn't made in the same form factor as the original, and it gets a little stuffy on the LV side of the power supply. But it's got to be done. JDW has a Mouser cart list that is really helpful, but some of the capacitors went out of date so you'll have to substitute others, using recognized good manufacturing source ones, from Japan.

What is the exact +5V and +12V readings?

 

[gf65]

Thanks for the recommandation on the extension cable.
This thread suggests using the standard atx cable which is wider but works, and could be cut if needed: https://68kmla.org/bb/index.php?threads/se-30-power-cable-connector-part-numbers.37973/

About what happened with the floppy drive, it seems the motors or something blocked as it didn’t operate properly until I switched off as I smelt the burn. Could it have damaged something on the motherboard, analog card or power supply unit ?
Is it something that can be fixed ?
I need to test the exact output voltage of the Psu.

 

[Mk.558]

Anything can be fixed, the question is what is wrong and how much it costs Except maybe a broken heart, that can be tough.

I should get an extension cable but I don't recall anybody selling them.

You may need to have the board looked at by an experienced specialist. There's a few here, but they're elusive and usually busy on other things. The good news is that it's a common machine. We won't know about the status of the FDD until the motherboard is cleared in good status. The power supply being recapped if it has not is a first-order business.

 

[gf65]

Hi
Thanks for this, it’s somehow reassuring
I recapped the motherboard 2 years ago and I know skilled people who can help me if needed.
I found this link for the analog board capacitors with jdw link to his video but I haven’t found the info for the power supply. Note that I have a spare Sony power supply that I can use.

Compact Mac Caps List

Logic Boards: Cap Values -> 1µf - 16V SMD 1µf - 50V SMD 10µf - 16V SMD 47µf - 16V SMD 100µf - 6.3V SMD 220µf - 16V - Axial 470µf - 16V - Axial Guides Mouser -> ✓ ✓ ✓ ✓ ✓ ✓ ✓ Digikey -> ? ? ? ? ? ? ? SE/30 1 10 1 1...

tinkerdifferent.com

When switched the Mac on again without the motherboard it seems to be ok but connecting the motherboard led to the Mac doing nothing (black screen, no noise) so I wonder if the motherboard has something damaged that prevents it all to work, if not damaging the analog board or power supply. Is there a way to test the motherboard ? Should I recap it again ?

 

[billbucks060]

Is it worth to remove and test each capacitor from the powersupply, analog board and motherboard, and only change the ones that damaged ?

 

[billbucks060]

Or could it be the flyback ? If so, I heard I could move the one from the SE analog board to the SE/30 (I'll take a photo of the analog board)

 

[chrisrueckert]

I'd suggest to replace all the caps. They have to be replaced anyway. The caps set from Console5 is only a few bucks.

 

[Mk.558]

According to mcdermnd, who has touched quite a few things, he thinks people blame flybacks way too often. Flybacks are for the CRT not the motherboard, and you'll know when a flyback is bad. In his experience they usually undergo catastrophic failure, and he's only fixed a few of them, it was usually something else.

Testing capacitors on on the power supply is in general, a waste of time. First you'll have to get a good LCR meter. Then you'll have to find the datasheet for the capacitor, and find out what testing frequency to use to see if it's in specification or not. The youngest of these machines is over 33 years old: the chances of the capacitor being in spec is slim. Basically every machine made before about the mid 2000s needs a full teardown and recap.

For a capacitor list, just check JDW's channel on youtube. He's got a full recap of both types IIRC. Hope you don't have the ASTEC supply.

 

[billbucks060]

I identified the issue: the VLSI UJ11 chip (floppy disk controller) blew so I'm planning to remove it. I will try to run the board without this chip to see if it works..