LCD Portable PC clone, display replacement

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LCD Portable PC clone, display replacement

Postby henryVK » 2019-2-28 @ 09:57

Howdy, friends and neighbours,

now, I've been trying to identify the best solution of swapping the monochrome LCD panel on this little luggable clone for a colour TFT. Well, usually these portable machines (Dolch PAC etc.) have some kind of dedicated PCI card or controller board that drives the TFT. That would be nice to have, since it would mean that the display is connected internaly and there's less messing around, but I don't think I want to wait for the right kinds of spares to show up on eBay/locally.

(There's this card here, but I can't figure out what kind of display it's meant for [22 pin LVDS?] – but if anybody has any idea, I'd still be curious to know if it's a viable solution. I've seen other TFT/PCI card solutions from point-of-sale or industrial displays, but they use these enormous 40 pin external connectors and I've only seen 12" or 15" screens, which would be too big.)

Okay. So, I've found these cheap little 10" IBM displays (here) that might just fit into the case and could just be connected with a VGA ribbon cable and a 90° adapter to the VGA-out – but here's where I have a couple of questions:

  • In order to ditch the separate AC adapter, could the display be run off the 12V that come from the PSU? There's these adapters from molex to 5.5mm barrel plug for LEDs and stuff like that.
  • Since it's not a native 640x480 screen, would this cause scaling issues with the graphics card?
  • This is a very cheap setup; could the display not simply be to... crap... to be worth the effort? They are IBM branded, but who knows.

I guess this last question is anyone's guess.

So, I'd be thrilled to have some advice on this, since I fear to be missing out on either some very obvious problem or obvious and much better solution :-D

Thanks and best regards

Henry
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-3-03 @ 12:39

Well, because I still didn't know whether this thing would actually POST correctly, I went ahead and picked up an S3 Trio32 graphics card by Spea for a couple of bucks:

Image
Mhh, messy.

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Bios can't remember that it doesn't in fact have a B: drive, but we'll solve that in time.

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Screen bezel

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This is the back of the old LCD in it's tray.

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Not a whole lot of room in there if I want to keep the tray.

So, the mainboard works, graphics work, floppy boots.

Next I'll try to figure out which screen I can get to work within the confines of the recess in the case, which is furthermore limited by the fact that the keyboard clicks in place in front of the screen. If the screen solution ends up taking more room than I can eke out in the recess, I'll either have to move components around the case or find a way to "extend" the mechanism that locks the keyboard in place.

(PS: dear mods, maybe this thread should rather be in "System Specs"? Feel free to move it.)
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-7-10 @ 13:52

After a couple of months in limbo, I made some progress on the screen bezel for my portable Pentium 1.

The 10.4" TFT I originally got for this machine turned out to be faulty. I spent a while testing all the components because I was a bit paranoid that something beside the screen could be producing the lines showing up on the screen.

Anyway, I found a refurbished Sanyo TM100SV-02L02 screen and controller board on eBay that works like a charm. It doesn't quite have the brightness of the NEC screen I had before, but the viewing angles are a lot better. The important thing is that it works and I was abled to move on to acutally making the screen bezel! I had researched 3D-printing or having something made out of sheet aluminium, but in the end I decided to see what I could come up with by myself. I ordered a couple of 5 mm FOREX PVC hard foam sheets and got some gray spraypaint from the hardware store, hoping it would match the grey-greenish colour of the portable case.

I got Forex because you can cut it with a boxcutter with a little bit of practise. I also remembered that I had some Tangit PVC glue which works like a charm.

Bezel cutout. I got it pretty straight on the second try.
Image


The panels are not too rigid, so I glued in these struts that also act as spacers to make sure the bezel sits flush.
They also serve to make the actual screen line up with the cutout, so placement had to be just so. The Tangit PVC glue bonds within minutes.
Image
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Bezel fits, paint looks reasonably good for a two-tone kind of affair.
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Screen assembly with shielding and controller board
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...and the first coat of paint had to come right off again because I decided to sand off all the edges... just used benzine and an old sock
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Four coats of paint later...
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This is what it's going to look like with the screen in place
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Things still need to come together, obviously, but I'm pretty pleased so far. I don't "craft" much, so there was a reasonable amount of trial and error. Now I only need to decide how to mount the screen assembly in the bezel and see that everything assembles alright.

My first instinct was to just glue the screen in place, mainly because it would give the best stability to the bezel, which is pretty floppy through those narrow strips and on account of not having any kind of edge profile to give it lateral rigidity. The disadvantage is that with something like JB Weld, it'd bond so well that, if I ever need to replace the screen, I'd probably be making a new bezel.
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Re: LCD Portable PC clone, display replacement

Postby PcBytes » 2019-7-11 @ 15:12

Tried some double sided tape? I know it can hold up pretty good, and it's used to bond some smartphone glass. (obviously you'd need the bigger type of double sided tape, not the small one used for smartphones)
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Re: LCD Portable PC clone, display replacement

Postby wiretap » 2019-7-12 @ 01:05

You can just make some little brackets out of thin sheet metal. Get a nibbler tool, some 20ga or so thick sheet metal, and cut out some rectangles. Bend them to form a z-bracket. Put a short self tapping screw through the side where you made the monitor surround, using the pressure of the z-bracket to hold the monitor in place. It should only take 4 brackets, one at each corner. That way if you want to remove the monitor, you can just unscrew the brackets or slide them 90 degrees to the side. I've mounted LCD panels to self-made bezels like this before and it has worked out well.

Example of a z-bracket:
Image
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-7-12 @ 07:03

Yeah, thanks! That about gave me the right idea, I think.

I'll try a combination of both. L-profile/brackets up against the struts to clamp the screen in place and some strategic double-sided tape "dots" to make it line up with the actual cutout. That should make sure it doesn't go anywhere and can still be removed!
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-7-16 @ 10:11

So, when I hooked up the screen for a test run I made my PSU go up in smoke, apparently because I had forgotten to check the polarity on the Molex-to-12V cable I made. Something shorted, I haven't even checked what it was yet...

Well, in other news the screen brackets worked out, so that's something.
I buffered the underside with this adhesive foam rubber that I normally use for camera light seals:
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...but everything else is a bit of mess right now. I wish for the umpteenth time that I had a proper workbench.

Front:
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Back:
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Screen power and VGA come out from underneath the mainboard, the other black cable is the audio-in for the speakers in the 5.25 bay
(Yeah, that is coin cell holder glued to a piece of styrofoam glued to what's left of the RTC module -- I'm a man of modest means)
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VGA and audio are eventually going to go out through a slot bracket with appropriate holes
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The cards are:
  • OPTI 82C930, OPL3-compatible (also branded as Magic S-22)
  • Winbond I/O card
  • Miro 22SD, Trio 64V+ 2Mb

Anyway, I'm going to talk to my dad about the PSU because I don't know much about power supplies and he's in electric motors, but most likely I will just replace it with a modern ATX. The original was 17x10x10 cm, so I figure that I can make a 12.4x10x6.3 cm mini ATX PSU fit into the case (with a hacksaw, plywood and PVC sheets).. so that should be a fun little diversion :happy:

"Wir eilen mit schwachen doch emsigen Schritten..."

"At a great pace but with feeble steps, we hurry along..."


–J.S. Bach
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-7-17 @ 12:40

Sweet moses, finally we can see some results with this thing!

I had a bit of a moment of panic with the mainboard because it wouldn't boot or even beep after I assembled everything again. Luckily it was just the ground cable for the screen that got stuck under the board and was shorting it out. I actually went home during my lunch break to sort that out -- talk about finding time for one's hobbies! :-)

Obviously, there's a lot of fiddling going on still and I haven't adressed the whole PSU issue yet, but I kinda needed to see how everything will come together:
Image

Sideways...
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The speakers don't sound bad at all, even though they're dinky little things. The volume knob was noisy as hell, but nothing a little contact cleaner couldn't fix! Also this thing might still need some legs sometime.. for now I'll shove a book (or screwdriver) under it.

Now I'm going to look for a PSU in earnest. It should be ATX, ideally with a rocker switch built in, new(ish) and as small as possible, since it's cramped enough inside the case as is. There's some likely candidates on eBay, but without actually holding them to the case it's hard to see if the dimensions work out. I'd like to avoid buying several, but we'll see about that.
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Re: LCD Portable PC clone, display replacement

Postby Thermalwrong » 2019-7-20 @ 13:32

That's looking superb - what a great outcome, a TFT makes a huge difference to these older machines :D

I really like how the facia and overall look turned out. It goes to show what can be done without goint to the trouble of 3d printing etc. In terms of style, it's quite a good fit for a machine like this as well, I think?
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Re: LCD Portable PC clone, display replacement

Postby keropi » 2019-7-20 @ 14:09

nicely done!!!
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-7-23 @ 09:48

Thanks, m'dudes!

I'm really pleased that I didn't resort to something expensive like 3d-printing that would have blown this project way outta proportion. TFT makes a big difference, definitely, and it's sorta in keeping period-wise, since this is a Pentium 133 after all. It's like the better version of my first very own setup, which was a 120 MHz Cyrix 5x86 paired with a 1 Mb Trident video card.

A couple notes on the screen:

  • native resolution is 800x600 which had me worried about VGA/SVGA scaling! SVGA in DOS looks decent enough. VGA I'm pleased with; however, there are oddities: in Prince of Persia I noticed that the image is a little larger than the screen, so a tiny bit on the right hand side is, in fact, missing (you'll notice if you look at the arabesque column at the right edge of the PoP title screen in my above post).. sorta inconsequential but still niggly. I haven't noticed this in other VGA Games but will do some testing.
  • aligning screen and bezel is... trying. It's just a little off to the left, and I'm a closet perfectionist, so I'll redo it sometime
  • the controller board gets awfully hot which is something I didn't anticipate. I'll redo the way it's mounted on the back of the screen RF-shield to give it more room to "breathe", as well as do a much larger cutout in the wall seperating the screen compartment from the mainboard to improve air circulation.

This last point has me worried, though. Worst case I'll have to work in a little 40mm fan.. next to the board? It can't mount it on top because there's just not enough room.

Anyway, here's some SVGA graphics:

Image
Image
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Re: LCD Portable PC clone, display replacement

Postby PcBytes » 2019-7-25 @ 09:47

henryVK wrote:[*]the controller board gets awfully hot which is something I didn't anticipate. I'll redo the way it's mounted on the back of the screen RF-shield to give it more room to "breathe", as well as do a much larger cutout in the wall seperating the screen compartment from the mainboard to improve air circulation.[/list]
This last point has me worried, though. Worst case I'll have to work in a little 40mm fan.. next to the board? It can't mount it on top because there's just not enough room.


I can note you have some bad caps on the board, these being the 4 brown caps (United Chemicon KZG/KZJ series most likely) near the power jack. These can cause ripple which is why it may get very hot, as it has to do extra work to keep it working properly. Replace them and post back if it still gets hot.
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-7-25 @ 10:11

Yeah, dead on.

Thanks for spotting that! I did notice that it was the caps that were creating the heat.

I'll have another look at what exactly they are. I thinks it's 1800uf 6.3V
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Re: LCD Portable PC clone, display replacement

Postby PcBytes » 2019-7-25 @ 11:43

henryVK wrote:Yeah, dead on.

Thanks for spotting that! I did notice that it was the caps that were creating the heat.

I'll have another look at what exactly they are. I thinks it's 1800uf 6.3V

I checked one of your pics, and they're 470uF 16v.
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-7-25 @ 12:38

Time to by some soldering tips!
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-8-02 @ 07:02

Right-o.

I replaced the questionable caps with Rubycons and ran the system for a bit while fiddling with sound drivers. Heat build-up is noticeably diminished, so big thanks to @PcBytes for this one! It still gets warm in the display "compartment" so I'll go ahead with making more room in order to optimize air circulation.

Also, my soldering iron is clearly not powerful enough for this kind of work; I had a hell of a time cleaning the solder out of the holes in the board! I keep meaning to do things like this at my dad's workshop, but he keeps going on vacations. Damn retirees! Also, also -- do you remember what it was like to just put your life on hold for a couple of days (or nights) to finish up some project? Yeah, me neither, and I don't even have kids yet.

So, last things on the list (hopefully):
  • biiiig, big cutout in the back of display compartment. I should really get a "japanese" saw, since I'm always using a loose handsaw blade with a rag wrapped around one end...
  • mount PSU in the case. Infuriatingly, it seems to be threaded for non-standard screws as none of my case screws fit.
  • make cutout for PSU power jack, maybe make some kind of bezel or cover if the edges end up looking too rough
  • reassemble
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Re: LCD Portable PC clone, display replacement

Postby xjas » 2019-8-02 @ 07:26

Looks REALLY sharp with the new display. I love this form factor but am put off by the smear-o-vision LCDs these things usually come with (even the TFT models from this era kind of suck.) Nice job!
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-8-02 @ 07:57

Thanks man! Glad you like it :blush:

The TFT one's are also just rarer than a white rhino! So, this whole project is basically just me running out of patience waiting for a Compaq 486c or a Dolch PAC.

If I can find another case like this for a reasonable price (they often go for >150€), I'll do a 12" version next :lol:

Actually, here's the VCFED-thread that inspired this build:

http://www.vcfed.org/forum/showthread.p ... table-486c
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Re: LCD Portable PC clone, display replacement

Postby henryVK » 2019-8-05 @ 09:41

Here's some picture of my PSU "mount". It's just two screw holes in the side and four in the back to loop the zip ties through.

Bit of a hack job, admittedly, but it does what it's supposed to! :lol:
I might replace it with a proper bracket when I have more time.

I kind of forgot to take more pictures of my progress, so I'll catch up on that in the next couple of days.

Image

Image
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Re: LCD Portable PC clone, display replacement

Postby DankEngihn » 2019-10-02 @ 17:05

Looks great! Any updates on this project?
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