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IBM 5155 MFM Hard Disk dimensions

robbo007

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Hi guys,
I managed to locate a hard disk for my IBM 5155. Its a Seagate ST 225. The plastic front cover seems bigger than the guides on the floppy bays (25mm bigger). Did IBM make a smaller plastic cover for these machines? I've measured it against my floppy drive and its a tiny bit bigger thus impeeding that I can get it in with the cover on. I'm inserting the hard disk from behind as the manual specifies. I don't really want to cut the plastic but don't see any other way?
 

twolazy

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Is it one the taller style ones that is like a bay and a 1/3rd? If so those wont fit. And finding that drive bay cover is a real pain, but not impossible. Took me a year to find one.
 

robbo007

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Its the small 1 bay size. Not the big 2 bay one. I think I might just cut a little off each side. Looks complicated to locate the original as you say.
 

Ruud

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I installed a XTIDE card that includes a CF card holder. Advantages: less weight, less power, more storage space and transferring files is just a matter of plugging the CF card in another system.
 

robbo007

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I did look into those but found a cheap 20MB drive locally. I much prefer to use original kit with my machines. If and when the disk dies I'll grab one for sure.
 

jafir

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So you’re saying that the ST225 drive you have had a wider bezel, not taller?

The ones I’ve seen have normally been either half-height or full height, but I don’t think I’ve seen one wider. I‘d assume that’s for some special use, like a case that doesn’t have standard drive bay openings.

Here is an example of an ST225 I have:

A8631F16-80F2-45CC-87A6-DCE4632964DE.jpeg

And the bezel seems to be the same size as the floppy drive. I’ve seen some drives that have a full height bezel, what looks like a “false front” you’d see on an old building in a western movies. :) and others mounted to a box to make them full height.

7B85BAD7-62F7-4DE8-BDC3-F1A6FED3DD3B.jpeg

427BA65F-BF23-49E4-B596-3CDF3F76F21C.jpeg
 

robbo007

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Interesting here's my bezel. You can see its got 3mm different which is just a too much to get the thing in without breaking it.
 

NeXT

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I ran into this with my ST225N. The faceplate bezel was slightly too large and would not fit the bay. I had to shave material off the bezel before I could make it fit but I suspect that if you try to use it on another machine again you will have a bezel gap.
 

robbo007

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I ran into this with my ST225N. The faceplate bezel was slightly too large and would not fit the bay. I had to shave material off the bezel before I could make it fit but I suspect that if you try to use it on another machine again you will have a bezel gap.
Yeah, that was my fear but I think I will do it as my chances of finding one will be very low. I don't think I'll be moving this disk to another machine. If I do it will be my 5160 which I have the bigger bezel. Maybe I could find someone to 3d print it? hmmm..
 

vwestlife

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The problem is not that the ST-225's faceplate is oversized -- it's that the Qume floppy drive's faceplate is slightly undersized, and that's what IBM designed the PCjr and 5155 cases to accommodate.
 

ibmapc

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The 5155 was not intended to have a hard disk installed internally. IBM provided the 5161 expansion unit to provide an external 10 MB hard disk. Kinda takes the "portability" out of the "Portable" 5155 though.
 

jafir

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Are there any blanks? Did 5155 ever come with just one drive and a blank in the other slot? If so maybe you could run a drive with no faceplate at all.
 

Eudimorphodon

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FWIW, if you actually lug around your 5155 that Seagate drive probably isn't going to hold up too well. Compaq's hard-disk equipped "Portable Plus" used a (very early) 3.5" hard disk mounted in a special shock-mount box with big rubber dampers to protect it. A naked ST-225 is going to take a beating, and hard.

With that in mind you might want to reconsider the XT-CF idea.
 

jafir

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Looking in the manual, it does look like there was a blanking plate, because they show just one drive in some drawings, but I’m not sure what the part number might be. 54AEA9C9-AAAE-44EE-A56D-59627B1C43B4.jpeg

I just opened the manual and was supersized to see it had info about the 5161, confirming what @vwestlife was saying. They do talk about internal fixed drives, but they only show the ones in the 5161, probably because the IBM supplied drives of the day were full height. And perhaps the sections suggesting the 5161 are optional just were copied from the 5160 manual?

440A58B8-21CD-4F4E-BE45-857922764292.jpeg
 

jafir

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Sorry for the spam. The forum doesn’t seem to easily let me edit posts with photos from mobile (which is were the photos are).

@Eudimorphodon here is an example I have, I think this is from a portable II but the idea is the same:

E9A47E11-310F-4EB2-A31E-3AFB75E20F7E.jpeg
 

NeXT

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FWIW, if you actually lug around your 5155 that Seagate drive probably isn't going to hold up too well. Compaq's hard-disk equipped "Portable Plus" used a (very early) 3.5" hard disk mounted in a special shock-mount box with big rubber dampers to protect it. A naked ST-225 is going to take a beating, and hard.
Another thing to add is that the 225 does not auto-park (though the slightly more intelligent 225N does) and Seagate's own documentation states the drive should not be transported unparked or operated in a vertical position, which you will do if you a carry a 5155 by the handle.

The blanking plate for the 5155 wasn't a standard option as that was for the base model single-drive systems.
Likewise I don't think IBM shipped any machine factory with a half height 5.25" hard drive until late in the XT or even into the AT era.
 
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