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Tube❄️Time

this RAM chip has a little attitude! actually it was working just fine. the bad chip was a different one. i replaced it and the machine booted!

a RAM chip with a pin bent so that it looks like a dog holding its leg up
44 comments
Tube❄️Time

even though it has a hard drive, it's not the 286 version of the Model 25 (the only versions to come with a stock hard drive). in fact it has been upgraded with the famous NEC V30! an 8087 has also been installed. someone tricked out this machine.

two chips on a circuit board: NEC V30, Intel D8087-1
Tube❄️Time

one thing is bothering me. i do not have the key for the keyboard/case lock.

a lock on the front panel of the computer. it has two positions, locked and unlocked, and it is set to the unlocked position.
Tube❄️Time

it was easy to remove, but i couldn't find out what kind it is. nothing at the local hardware store matched. spoiler: it is something special.

Tube❄️Time

after a ton of research, it turns out to be a Medeco Biaxial lock (original) but with a rare 3-pin arrangement. since the front face does not have a logo, this is likely a special version made just for IBM. lockwiki.com/index.php/Medeco_

Tube❄️Time replied to Tube❄️Time

looks like this brass cover slides open to reveal a spring and the first pin.

Tube❄️Time replied to Tube❄️Time

here are the pins all laid out in front of the lock. they are special because, besides being pushed to the correct height, they have to be rotated to the correct angle as well! (there were 3 possible angles). you can see false holes and other anti-picking features.

Tube❄️Time replied to Tube❄️Time

i have an idea. but first i need a really good image of the keyway.

Tube❄️Time replied to Tube❄️Time

here's a 3D model of a part that should slide right in.

Tube❄️Time replied to Tube❄️Time

it turned out pretty well, i printed it with a 0.3mm extruder on my Ender 3. it also fit the lock!

Tube❄️Time replied to Tube❄️Time

using an iterative process i wound up with this key.

Tube❄️Time replied to Tube❄️Time

looks pretty good if i do say so myself haha

Tube❄️Time replied to Tube❄️Time

the 3d-printed key fits the lock! you can see how the angle of the cuts causes the pins to rotate and orient properly.

Tube❄️Time replied to Tube❄️Time

the moment of truth: and it works! the 3d-printed key is really not quite strong enough for everyday use, but i'm quite pleased since this is the first lock that i've reverse engineered.

3d printed key in the lock on the Model 25. it's been rotated to the locked position!
Jeff Haluska replied to Tube❄️Time

@tubetime Even with tumbler disassembly, I'm so surprised you got it to work.

I also wonder if it's cheaper to have a locksmith make a key from that or try to use it for a mold.

Blacksmith replied to Tube❄️Time

@tubetime I guess you could get a metal key cut from it at the local hardware.

Tube❄️Time replied to Blacksmith

@Blacksmithoz specialty item, i'd need to go to a locksmith

Ewen McNeill replied to Tube❄️Time

@tubetime your Medeco Biaxial key reverse engineering feels like something @deviantollam would be interested in. He might also be able to suggest where you could get a suitable metal blank to suit your pinning (or to suit a repinned version).

(3D printed sintered metal probably also isn’t strong enough for frequent use, but a metal key cast from the negative of your reverse engineered key model might be sufficient for light use.)

Tube❄️Time replied to Ewen

@ewenmcneill @deviantollam i found his video on the pinning tray, so that was helpful.

Deviant Ollam replied to Tube❄️Time

@tubetime @ewenmcneill I absolutely love what I'm seeing here.

If there are notes or files available for the working model of the key (especially given that this key way I believe may have been reused in other applications) I and others could drive great benefit from seeing that information. :-)

Absolutely awesome work, I love how you figured it out seemingly working in isolation which is doing it on hard mode. :-)

Your results are terrific and the fact that you're willing to show people and be an inspiration to others is so commendable. 👍😁👍

@tubetime @ewenmcneill I absolutely love what I'm seeing here.

If there are notes or files available for the working model of the key (especially given that this key way I believe may have been reused in other applications) I and others could drive great benefit from seeing that information. :-)

Absolutely awesome work, I love how you figured it out seemingly working in isolation which is doing it on hard mode. :-)

Tube❄️Time replied to Deviant

@deviantollam @ewenmcneill thanks for the kind words. right now it is just some random notes and a crappy solidworks file. i am not convinced i have the depths right. i also have another lock (with no key) of very similar make, so i'll probably take that one apart and compare the pinning

benjohn replied to Tube❄️Time

@tubetime I wonder if there's a standard metal blank that matches that? You could perhaps have a metal copy made of this plastic key at good fidelity?

Tube❄️Time replied to Tube❄️Time

trying to get a metal blank might be hard. the IBM documentation claims it is a restricted keyway made by Medeco, custom for their computers.

Ordering Keys For protection against unauthorized key duplication, the key mode switch is equipped with a Medeco® high security lock. Keys for this lock are a factory restricted series, and duplicate keys are not available through normal commercial channels. The metal code tag supplied with your original keys authorizes you to purchase additional keys directly from the Medeco factory. The additional key supplied and the metal tag should be stored in a secured area.

To obtain information or replacement keys, use the following list to contact the Medeco distributor most convenient to you. Complete a copy of the order form on the next page and mail it to the distributor. As a security precaution, Medeco will not honor orders that do not include both the code tag and the official order form.

Should the key mode switch become inoperative, contact your sales representative for replacement.
arclight replied to Tube❄️Time

@tubetime Sounds like a job for Lock Picking Lawyer or someone with a mill and a bench grinder.

Thilo, EE 🤘🏼🇪🇺⚛🎗️ replied to Tube❄️Time

@tubetime Pretty impressive reverse engineering there. Impressive!
I wonder if there aren't fellow makers who could make a metal copy of your design. Apparently, you have all the dimensions and angles ready for production.

First idea would be James from Clough42 on YouTube. He seems really skilled with 3D CAE and delicate CNC machining.

UpLateGeek replied to Tube❄️Time

@tubetime you’ve already got a working model for an FDM printer, so I’m wondering if this would also work in a SLS metal printer? No idea what the cost of the print would be though. Or you could have a go at making a high temperature silicone mould of the key and casting it in pewter.

Dave Bittner replied to Tube❄️Time

@tubetime “Hello, this is the Lockpicking Lawyer…”

Tube❄️Time replied to Tube❄️Time

another day, another lock. I designed a little pinning tray to make it easier to compare pins.

Interpipes 💙 replied to Tube❄️Time

@tubetime neat! Could you get an outfit to print you a copy in metal with DMLS? I have no idea how much such a thing would cost

Richardus replied to Tube❄️Time

@tubetime it saves the day to get things working again. Very nice.

Ove Gram Nipen replied to Tube❄️Time

@tubetime Nice work! Now that you have the shape, it could be possible to cast it in bronze :)

UpLateGeek replied to Tube❄️Time

@tubetime put another way, the iterative process was the key.

Neko May replied to Tube❄️Time

@tubetime I see someone sprung for the high security option! Our 7011 has the Medeco lock option, as well. Was a special upsell!

Tube❄️Time replied to Neko

@NekoEd what was the standard option? tubular?

Neko May replied to Tube❄️Time

@tubetime Not sure, it's been a while since I looked it up. On the 7011 it's a case lock *and* function switch (Normal/Service/Secure), so it may have been a standard flat key.

[DATA EXPUNGED]
Tube❄️Time

@HoustonDog if you don't have a compatible keyboard but the port itself works, maybe build an Arduino-based converter from PS2. if the port is dead, well, fix it already 😉

[DATA EXPUNGED]
Tube❄️Time replied to DELETED

@HoustonDog what leads? why not just replace the capacitor?

Adam Brisebois (YesterGearPC)

@tubetime Oooh interesting. My 25 doesn't have this lock. Mine was a single floppy model, and the right bay is just 100% blank.

Neil

@tubetime Seems like a majority of the PS/2 Model 25 I find for sale are the 8086 monochrome variant. Kinda want to get one of the 286 color variant sometime—just like the ones my middle school had—although it’s a low priority. (Apparently there was a 386 variant too but I expect it to be hard to find.)

Elsa Star Trewyn

@tubetime 😍 It's a cute little chip with all those little legs!

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