IBM PCjr retro

Hardware questions and modifications

IBM PCjr retro

Postby Archetype » Tue Jun 09, 2015 2:13 pm

Hello, fellow juniors. My journey in life too, has included the infamous PCjr. For me, owning a PCjr turned out to be like owning the DeLorean from Back to the Future without any plutonium to power it; Unlike my Commodore 64, which I sold in order to buy the jr, there was no network of fellow users to share knowledge or experience with and dwindling software suppliers made acquiring anything usable increasingly impossible in a matter of months. Many years later I learned about the mail order business of 3rd party hardware and software vendors. But it was far too late by then. Aside from the handsome IBM binder books that came with it, King's Quest, DOS 2.10, and Cartridge BASIC, the machine became a bitterly expensive paperweight in my house.

30 years later I have returned...to redeem both myself and the infamous PCjr with this retro build project!

Project goals:
* Retain as much original structure as possible
* Stay true to the spirit of the original
* When cuts are necessary, keep them clean
* Pleasing aesthetics
* Hardware should allow for a solid, modern, general computing experience
* Must be able to play Team Fortress 2, Bioshock 1, 2, and Infinite with no lag at medium or high quality

I do not still own my original PCjr from 1985; I honestly do not remember what became of it. So, for this build, I started simply with an empty shell- case top, bottom and bezel, which I got off eBay for cheap:
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So, I did not waste any hardware internals.

The ABS plastic was decent, but slightly yellowing. The item description was simply, "Very Good condition", but much to my dismay, the side cover of the case was missing.
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After contacting the seller about the description mentioning nothing about this, he bluntly told me to return it....but, I figured

...nothing a little Komatex can't fix. I measured up a piece and cut it out on the bandsaw:
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After sanding the edges smooth with 400 grit paper, I mixed up some Gorilla epoxy:
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And pressed it on:
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Prepped surfaces with some DuPont 3812s:
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Carefully masked the IBM case badge, rubber feet and manufacturing label with 3m auto body masking tape:
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Shot it with Krylon Fusion satin white:
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After re-assembly:
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After 30 minutes of careful filing, dry-fitting a 3 port USB hub in front left portal:
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Shot of PCjr original case rear, courtesy of Google images:
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I decided rather than hack the old case rear to mount the motherboard I/O panel flush with it, I would simply extend the ports from within via cords and hubs, to preserve the original look.

Here's the original modem RJ11 jack portal before:
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..and after filing:
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Dry fitting new RJ45 for ethernet:
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Fits right in there..

Card reader fitted into rear ports:
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I am told real men skip the Dremel and go straight to a RotoZip. So that's what I did for the C14 port:
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After fastening with case screws. Also note 4 port USB hub:
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Here's a stacked before and after for the case rear.

Typical original jr rear, courtesy Google images:
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2 Joysticks, Spare, keyboard, light pen, TV, RCA video, RJ11, CGA video, serial, cassette, power input, power rocker switch, audio out

Functional case rear, now modified for modern computing. (After):
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C14 power jack, USB ports, microphone jack, ethernet, card reader, HDMI and speaker jack. Above is a momentary contact rocker switch for ATX power.

More Komatex cut on the band saw for filling in the old 5.25" floppy slot:
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After sanding, it fits right in:
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Scribing a line for the low profile DVD drive door:
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I hand cut this with just a plain razor, which was not easy! After about 30 minutes of careful and painstaking slicing and re-slicing I then sanded the rough edges with 400 grit paper and wiped down with 3812s:
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After painting with Krylon and assembling the drive:
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I also covered the right port with Komatex and placed a waterclear red HDD LED, which is reminiscent of the original floppy LED.

I got a really cheap, Chinese mechanical keyboard on Amazon that is just the right size:
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Removed branding with Mr. Clean Magic Eraser:
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Shiny, metal IBM decal:
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And....
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Wink, wink.
Also note addition of AMD A10 decal added beside case badge. (Like this build, some original PCjrs did, in fact, include AMD CPUs!)

Because of the inherently poor case ventilation, I needed a cool running, low wattage chip:
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The 7800 has 4 compute cores, running up to 3.9GHz and 8 R7 graphics cores. A BIOS setting allows toggling between 65 and 45 watts. I have her running at 45w TDP, and temps never go above 55c. Performance is snappy. And 3d graphics are actually better than expected.

I wanted to use the hole in the middle of the front bezel where the wireless keyboard receiver sat for a green power LED- Something akin to a pilot light peekhole on an old gas furnace or boiler. I tried adapting a 5mm and then a 10mm LED to fit in the hole, but they looked awful and protruded horrifically. I finally achieved the effect I was looking for by taking the plastic magnifying lens of a broken LED flashlight and fastening it in the hole with hot glue, and then gluing the 5mm LED in back of the lens:
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It is difficult to effectively photograph, but to the human eye, this looks really neat. There is a nice, eerie glow, and a depth captured in the magnifying lens that grabs attention.
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Internals:
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New Specs:.......................................................................................My Old PCjr Specs:
AMD A10 7800 3.9 GHz @45w TDP............................................................AMD D8088 @ 4.77 MHz
8 GB Crucial Ballistix RAM.....................................................................128KB RAM
Asrock FM2A88X-ITX+ Mini ITX Motherboard...............................................IBM PCjr motherboard
Solid Gear 320W Mini ITX PSU.................................................................40 watt PSU
WD Black 750GB 2.5" HDD and slim line DVD burner.....................................5.25" Floppy, 360KB
1 Startech 70mm intake fan, volt-modded to 5vdc, for quiet operation............Passive cooling (Floppy drive included a rear fan)
Windows 8.1 with Classic Shell™.............................................................MS DOS 2.10

Here's a shot of the replacement side panel that I fabricated from Komatex, which I am quite happy with:
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And that about does it. Using a Samsung 20" LCD monitor I repaired with a capacitor kit and painted white:
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Thanks for viewing.
Archetype
 
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Re: IBM PCjr retro

Postby Hargle » Wed Jun 10, 2015 6:52 am

simply amazing! Thank you for the extensive write up with photos.

I had a similar idea not too long ago when I realized that a PCjr with 2 sidecars almost fits in a 2u rack space. It's a bit too tall with the feet installed, but that's easy enough to take care of... If I could get one of your units with a set of wings to hold it into a rack mount, my computing life would be complete. Want to build another one? :)
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Re: IBM PCjr retro

Postby MikeModified » Wed Jun 10, 2015 9:13 am

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Re: IBM PCjr retro

Postby geoffdaddy » Thu Jun 11, 2015 12:14 pm

Kudos! Looks great. The thing I love most about the jr is the small footprint. Nice to be able to stuff modern hardware in there.
PCjr: 10MB RACore 01 hard drive expansion, Hotshot 640kB RAM expander, optical mouse, Xircom PE3, speech sidecar.
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Re: IBM PCjr retro

Postby Archetype » Fri Jun 12, 2015 5:09 am

Hargle wrote:simply amazing! Thank you for the extensive write up with photos.

Thanks for your kind words.
Want to build another one? :)

Heh. Seriously? It could happen...care to discuss?
geoffdaddy wrote:Kudos! Looks great.

Thanks so much.
MikeModified wrote:Yes, really cool!

I appreciate it, thanks!
Is this what you used?....

Yes. That's the chip. Excellent value.

I am very honored by your positive response, guys. Thanks so much.
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Re: IBM PCjr retro

Postby jmetal88 » Sat Jun 13, 2015 7:06 pm

Man, maybe I should try something like this with my spare PCjr that I damaged the motherboard for.
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Re: IBM PCjr retro

Postby GHiero » Mon Jun 15, 2015 12:38 pm

If you spray painted the chassis black, the case would not look out of place next to the typical low profile Dell and HP workstations you find these days.
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Re: IBM PCjr retro

Postby Eric » Mon Jun 15, 2015 9:01 pm

You know, That looks amazing.

I'm more into restoration than retrofitting, but this is clean enough to have my respect.


There are a few things I would personally try to get this to the max. What I would do is get a busted PCjr display, gut the case and fit a more modern CRT into it and possibly resuse the speaker.


For overkill, I'd etch some PCB for a new keyboard and fit it into the revised pcjr keyboard's case, and make some cuts and stuff some MX Cherry Blue mechanical switches into it. Or buckling spring switches to make it more like a model M. Mwahahahaha.

I'd probably not get around to all that, but if it's something I manage to find myself doing, those are things I'd try.

Not saying you should do all that. You did do a neat job. I like it. Just wish it had the sexy monitor and keyboard. >;3
PCjr:
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Re: IBM PCjr retro

Postby Archetype » Tue Jun 16, 2015 6:11 am

Eric wrote:You know, That looks amazing.

I'm more into restoration than retrofitting, but this is clean enough to have my respect.

Thank you very much.

There are a few things I would personally try to get this to the max. What I would do is get a busted PCjr display, gut the case and fit a more modern CRT into it and possibly resuse the speaker.

I had planned on fitting a 4:3 LCD into an old case but gave up, at least temporarily; there were no non-working monitors available when I looked. I figured it would be a shame to hack up a working piece of history and continued without it.

For overkill, I'd etch some PCB for a new keyboard and fit it into the revised pcjr keyboard's case, and make some cuts and stuff some MX Cherry Blue mechanical switches into it. Or buckling spring switches to make it more like a model M. Mwahahahaha.

The thought crossed my mind, (green switches though) believe me. My pragmatism has always been a limiting factor of my creativity. You know what I mean? I guess I also know myself well enough now to realize that I probably would get bored with the project before completing it. I would also need to rely on someone to etch the PCB for me.
I'd probably not get around to all that, but if it's something I manage to find myself doing, those are things I'd try.

It could happen. My enthusiasm may well up and motivate me!
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Re: IBM PCjr retro

Postby Hargle » Tue Jun 16, 2015 7:12 am

FWIW, I have at least 2 non-functional PCjr monitors in my possession. I was going to try and merge them together to make 1 working monitor, but that is likely outside my skillset and danger/comfort level, not to mention my available time. If someone wanted to actually go the route of retrofitting a PCjr monitor, I would be more than happy to empty my closet for them.
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