WinBook SLC and SX/DX
The WinBook SLC and SX/DX are 486-based laptops that were released in 1993. The SLC was released in March and was the first WinBook laptop. At launch, it was only available with a grayscale LCD, with a color option releasing a couple months later. In October, WinBook released the SX/DX Series, which used desktop 486 processors instead of a soldered Cyrix Cx486SLC chip. These laptops support up to a DX2-66 and were available with grayscale and color LCDs. All LCDs for both models were passive matrix.
These laptops were one of the first to be designed with Windows in mind rather than MS-DOS, thus the name. They were one of the very first PC laptops to place the trackball below the keyboard, and scored points for this in reviews.
The SLC and SX/DX were both manufactured for WinBook by Jetta Computers Co. LTD, a Taiwan-based Original Design Manufacturer (ODM). I believe the design was at least partially done by WinBook - they said in advertising material that they had Palo Alto Design do it. That being said, these laptops were not exclusive to WinBook, and Jetta sold them to their own dealers as Jetbooks, as well as to other companies. You'll usually see these up for sale as "Jetta WinBooks" because the label on the bottom still has Jetta's name on it.
Model Numbers
The WinBook SLC models numbers (as printed on the bottom label) are 486SLC-25 (grayscale) and 486SLC-25C (color). Some early advertising materials refer to the CPU being 33MHz, but I don't believe any actually shipped this way. I have however seen a Jetbook branded unit with the model number 486SLC-33. The CPU in my WinBook SLC is also marked as a 33MHz part, but is running at 25MHz.
The SX/DX model numbers are 486C2SX-25, 486C2SX-25C, or similar. C2 comes from Jetta - they called these the Jetbook C2 Series. Anything other than SX-25 CPUs seem to be rare in these models, but I did find a reference to a 486C2DX2-66C after some digging, so all model numbers for these should follow that same format.
Specifications
| Spec | SLC | SX/DX |
|---|---|---|
| Release Date | March 1993 | October 1993 |
| CPU | CPU Type: Soldered QFP Cyrix Cx486SLC @25MHz - Optional CX83S87 Coprocessor | CPU Type: Socket 2 - Intel 486SX @25MHz - Intel 486DX @33MHz - Intel 486DX2 @50MHz |
| Chipset | Unknown | PicoPower Evergreen PT-86C268 |
| RAM | Type: WinBook SLC Proprietary Standard: 4MB Maximum: 8MB | Type: WinBook SX/DX Proprietary Standard: Unknown Maximum: 32MB |
| Storage | 2.5" IDE Requires Adapter: Yes Standard: 85-340MB | 2.5" IDE Requires Adapter: Yes Standard: 120-340MB |
| Display Options | - 9.4" Passive Matrix Grayscale LCD @640x480 - 9.4" Passive Matrix Color LCD @640x480 | 9.4" Passive Matrix Grayscale @640x480 - 9.4" Passive Matrix Color @640x480 |
| Graphics Chipset | Mono: Cirrus Logic GD6420 Color: Chips & Technologies 65530 VRAM: 512KB | Chips & Technologies 65530 VRAM: 512KB |
| Audio | PC Speaker | |
| Main Battery | NiMH (8-cell, Sanyo) | |
| CMOS Battery | Varta 3-cell NiCad | |
| Power Supply | Kycon KPPX-4P Connector - Jetta/Union Circle UCT-90042-16 | |
| Media Drives | 3.5" 1.44MB Floppy Drive - Mitsumi | |
| PC Cards | 1x 8-bit PCMCIA | 1x 16-bit PCMCIA |
| Networking | Modem (Optional) | |
| Other I/O | - 1x Parallel - 1x Serial - 1x VGA Out - 1x Dock Connector - 1x PS/2 Mouse Only | - 1x Parallel - 1x Serial - 1x VGA Out - 1x PS/2 (Mouse Only) - 1x Dock Connector |
| BIOS | AMI | SystemSoft |
| Pointing Device | Trackball | trackball |
Resources
 Drivers (SLC) |
Drivers (SX/DX) |
 User Manual (SLC) |
User Manual (SX/DX) |
Archived Support Pages (SLC) | Archived Support Pages (SX/DX) | Older FAQ (SLC) | Older FAQ (SX/DX) | AC Adapter Pinout |
|---|
Common Faults & Maintenance
Compared to some other laptop models I've seen, these WinBook models have held up pretty well electronic wise, all things considered. Still, I've run into trouble in a few areas - specifically with the display hinges, keyboards, floppy drives, and the DC power modules.
Hinges and Brittle Plastic
All plastic parts on these laptops go extremely brittle with age. The plastic will split 100% of the time around both hinges within around 10-15 hinge uses. In order to fix this, you will have to use JB Weld to rebond the two pieces at each hinge, along with adding some extra JB Weld around the area to reinforce it. This has worked very well on my SLC, and it is still holding up as of February 2025 after repairing it in around May 2023. This fix also worked on my SX/DX WinBook, although it did break again at the left side, requiring another round of JB Weld to fix. My SX/DX has much stiffer hinges than my SLC, so that makes sense.
CMOS Battery Leaks
The Varta NiCad CMOS battery in these laptops is highly prone to leaking and should be removed first thing. Thankfully, it isn't right near critical components.
Keyboard Failure
The keyboard ribbon cables are very fragile on these! In the process of taking my SLC unit apart, unbeknownst to me, I caused some micro-fractures inside of one of the two ribbon cables coming out of the keyboard, which caused multiple rows of keys to stop working. This is a bit of an issue, as one key that no longer works is F1, which is required to boot past the BIOS. And as noted on the main page on these, the PS/2 port does not work with external keyboards, so I literally cannot boot the system, despite it working otherwise.
The fractures are caused due to the cable being bent in one spot for 30 years, then unbent when you go to open the system. To prevent this from happening, do not unbend the creased cable if possible when disconnecting the keyboard. You'll have to flex it a little bit, but avoid it as much as possible, or you'll get the micro-fractures in the conductive tracks, and the keyboard will no longer work. I managed to take apart my SX/DX without causing this same damage.
So, what if this did happen, or if you suspect someone else caused it in the past. Well, I have an idea for a fix, which was given to me by twolazy from the VCF forums. The method that they have used is to use steel wool to remove the top coating from the damaged area in order to gain access to the inner conductive tracks. Then, a very careful application of conductive glue would be used to repair the breaks. I haven't tried this fix yet.
Capacitors
Good news - you won't find a single surface mount cap across the entire system! You aren't fully in the clear though - there are several through-hole electolytic capacitors on the DC Power Board. Coincidentally, the 486SLC-25 model happens to have an issue where it won't warm boot after running for a few minutes. It will stay on for as long as I want it to, but then when I go to shut it off, if it's been on for more than a few minutes, it will power on, spin up the hard drive, then show no display and it fails to POST beep. I haven't yet recapped the DC power board, but weak old caps there is my main suspect. As for the display assembly, the grayscale models have no electrolytic caps on the LCD at all, and the color model only has through hole electolytics. Not that those can't fail, but they won't usually leak as bad. I'd still like to replace them in my C2SX-25C soon, and you probably should too if you have one. I'll be sure to upload cap reference info here when I get around to recapping mine.
(The rightmost capacitor is not bulging, it only appears to be in the photo)
Floppy Drive Issues
The WinBook 486SLC/SX DX Laptops use a slimline 3.5" floppy drive manufactured by Mitsumi. These drives do not normally work anymore, largely due to a drive belt that deteriorates with time. I have not yet found an available replacement, although I will keep working towards finding a replacement.
Gallery
486SLC-25
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486C2SX-25C
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Docking Station
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Page last updated (MM/DD/YYYY): 03/09/2025
Update Reason: page converted to php
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