Regarding item 3) in your plan:
Check for shorted power rails in both directions (i.e. check the connector on the board to ensure that no caps on the board are shorted, and check the connector from the power supply to ensure the power supply itself isn't shorted).

Regarding item 4) in your plan:
If your system is the same as the one in this video, jump to offset 19:59 for some useful info on replacing the battery:
https://www.youtube.com/watch?app=desktop&v=x0zQYWQsnz0

mx597 wrote on 2024-10-02, 01:18:

Check for shorted power rails in both directions (i.e. check the connector on the board to ensure that no caps on the board are shorted, and check the connector from the power supply to ensure the power supply itself isn't shorted).

Good point, will certainly do.

mx597 wrote on 2024-10-02, 01:19:

Regarding item 4) in your plan:
If your system is the same as the one in this video, jump to offset 19:59 for some useful info on replacing the battery:
https://www.youtube.com/watch?app=desktop&v=x0zQYWQsnz0

Yep, that's the battery. I didn't look that closely and just assumed it was rechargeable. But you are right.

It looks like the original battery is still available
3 V 1.2 Ah
https://www.mouser.com/ProductDetail/Panasoni … jcsr56YCHd0Q%3D

CR2023 is
3 V ~0.225 Ah

In case it helps anyone else, the CR2032 battery holder in the video above appears to be one of the following:
either:
https://www.mouser.com/ProductDetail/Eagle-Pl … 2Be7X%2Fg%3D%3D
or
https://www.mouser.com/ProductDetail/Keystone … dG1Z0TeJQ%3D%3D

Are leaking caps in the floppy usually pretty obvious, or should I just plan to replace all the electrolytics?

Also, I noticed on the riser card that there appear to be several tantalum caps...only they have 3 legs. It appears the outer legs are connected. A quick search suggests this was done to prevent someone from installing them backwards?
Apparently on mouser they can be found by searching for "Radial Dipped 3-Lead Tantalum Capacitors - Solid Leaded".
Had never seen one before. I guess it's two tantalums in one arranged so that it's like a non-polar electrolytic?

Dang can't edit my post.

Correction:
Panasonic 3V BR-2/3A
3 V 1.2 Ah

CR2032 is (not CR2023)
3 V ~0.225 Ah

Guld wrote on 2024-10-03, 00:18:

Are leaking caps in the floppy usually pretty obvious, or should I just plan to replace all the electrolytics?

I don't have any experience with these floppy drives myself, but in case you haven't already found this, here is a video dedicated to IBM PS/2 Model 30 floppy and HD issues. From around 1:00 to 4:00 the video focuses on capacitor issues in the floppy drive and contains some useful info.

Guld wrote on 2024-10-03, 00:18:

Also, I noticed on the riser card that there appear to be several tantalum caps...only they have 3 legs. It appears the outer legs are connected. A quick search suggests this was done to prevent someone from installing them backwards?
Apparently on mouser they can be found by searching for "Radial Dipped 3-Lead Tantalum Capacitors - Solid Leaded".
Had never seen one before. I guess it's two tantalums in one arranged so that it's like a non-polar electrolytic?

As far as I know, you're correct, the two outer legs on 3 legged tantalums are the same terminal... that way you can insert them into a board "forwards" or "backwards" and the connections are the same. I think it was meant to make hand assembly easier by not having to worry about polarity. As far as the internals go, I don't think it's two tantalums as that would be more expensive to manufacture, I think it's a single tantalum where the outer leads are connected. If I recall correctly, I remember seeing a diagram a long time ago whereby the outer leads are essentially an upside-down U and the internal connection to the capacitor is at the bend in the U.

mx597 wrote on 2024-10-03, 23:57:

As far as the internals go, I don't think it's two tantalums as that would be more expensive to manufacture, I think it's a single tantalum where the outer leads are connected. If I recall correctly, I remember seeing a diagram a long time ago whereby the outer leads are essentially an upside-down U and the internal connection to the capacitor is at the bend in the U.

Ah, that would make sense.

You can use a high density PS/2 floppy drive on a model 30. The drive will still operate as a double density drive. The system's controller just won't be able to read high density floppies, even though the drive is capable.

I never replaced the battery in my model 30, it still had a sufficient charge. Despite being at least 35 years old. I have also had great luck with those Panasonic lithium cells. Never had one leak, even in some very abusive circumstances.

While a standard PC floppy drive won't match the case profile, there are adapter cables that can make one work in a PS/2. This can be an option for testing purposes.

mx597 wrote on 2024-10-03, 23:46:

Guld wrote on 2024-10-03, 00:18:

Are leaking caps in the floppy usually pretty obvious, or should I just plan to replace all the electrolytics?

I don't have any experience with these floppy drives myself, but in case you haven't already found this, here is a video dedicated to IBM PS/2 Model 30 floppy and HD issues. From around 1:00 to 4:00 the video focuses on capacitor issues in the floppy drive and contains some useful info.

I just noticed that I forgot to include a link to the video I mentioned:
https://youtu.be/pHqJnSNobT0?si=d7al0_VbWgorjUiE

mx597, thanks for the link!

akimmet wrote on 2024-10-04, 01:58:

You can use a high density PS/2 floppy drive on a model 30. The drive will still operate as a double density drive. The system's controller just won't be able to read high density floppies, even though the drive is capable.

I never replaced the battery in my model 30, it still had a sufficient charge. Despite being at least 35 years old. I have also had great luck with those Panasonic lithium cells. Never had one leak, even in some very abusive circumstances.

While a standard PC floppy drive won't match the case profile, there are adapter cables that can make one work in a PS/2. This can be an option for testing purposes.

Yeah, I actually check the voltage the other day and it was still around 2.9 volts. I was surprised, 🤣.

All the hard drive and floppy capacitors look okay, I don't see any signs of bulging or leaking on any of them. Doesn't mean it will work of course.

Here are the 2 cradle adapters I've seen (I think they are really probably the same model in two different locations but not sure).
https://github.com/schlae/PS2FloppyAdapter?ta … =readme-ov-file
https://www.thingiverse.com/thing:4774831

The early miniature surface mount capacitors used for PS/2 floppy drives and hard drives are well known to fail. Unrestored working examples are exceptionally rare.
Like you noticed, these capacitors rarely exhibit signs of physical leakage. It is almost certain they are bad anyway.

akimmet wrote on 2024-10-04, 16:38:

The early miniature surface mount capacitors used for PS/2 floppy drives and hard drives are well known to fail. Unrestored working examples are exceptionally rare.
Like you noticed, these capacitors rarely exhibit signs of physical leakage. It is almost certain they are bad anyway.

You might want to look into my post at Let's fix some PS/2 floppy drives! regarding bad capacitors in those drives.

akimmet wrote on 2024-10-04, 16:38:

The early miniature surface mount capacitors used for PS/2 floppy drives and hard drives are well known to fail. Unrestored working examples are exceptionally rare.
Like you noticed, these capacitors rarely exhibit signs of physical leakage. It is almost certain they are bad anyway.

Dang, yeah, usually I just expect the electrolytic to be a problem.

Anyone have a schematic of which of the SMD are capacitors and which are resistors and their values? I'm not that great at telling them apart usually. Will certainly lengthen the amount of time to repair it but still doable 😀.

Also, checked the motherboard, no apparent shorts.

The power supply, however, is showing the -12 and +5 as shorted to ground. Haven't opened it up yet, will be a little bit until I have time to open it up and see. Anyone have any recommendations for what could be wrong in the power supply? I typically only work on the low voltage stuff 😀.

mkarcher wrote on 2024-10-04, 19:03:

akimmet wrote on 2024-10-04, 16:38:

The early miniature surface mount capacitors used for PS/2 floppy drives and hard drives are well known to fail. Unrestored working examples are exceptionally rare.
Like you noticed, these capacitors rarely exhibit signs of physical leakage. It is almost certain they are bad anyway.

You might want to look into my post at Let's fix some PS/2 floppy drives! regarding bad capacitors in those drives.

Oh nice! I certainly will, thanks for pointing me at it!

My drive appears a little different. I don't have the organic caps like you have on your post and as were shown in the video posted earlier. Just electrolytic and surface mount...maybe one polyester, didn't look at it that closely.

Here are some pictures, it's a Toshiba FDD4451A0Z11 G01

And now that I look at it again, they have clearly labeled the surface mount capacitors, so at least I know which they are (on the floppy at least, not sure about the hard drive). But I would have no idea what voltage rating or capacitance to use to replace them. Granted overkill on the voltage should be easy enough, but no idea if they are 10 uF, or who knows.

The surface mount caps on your Toshiba drive are multilayer ceramic capacitors (MLCCs). While MLCCs can crack and sometimes go short if they are cracked, they don't generally degrade over time. Unless you have strong evidence that one of the ceramic capacitors is broken, I would not even think about replacing them. Just test the drive as it is now, it will likely work, possibly you need to clean the heads, though.

mkarcher wrote on 2024-10-04, 19:03:

You might want to look into my post at Let's fix some PS/2 floppy drives! regarding bad capacitors in those drives.

Very informative, I was unaware that anyone had put any effort into reverse engineering the motor drive PCB.

I'm not a huge fan of blind capacitor replacement. Unless it's a known widespread problem.

I don't see any surface mount electrolytic capacitors on the Toshiba drive in question.
It may just work as is after some cleaning.