IBM ThinkPad 755 Series
The ThinkPad 755 Series were desktop replacements sold by IBM from June 1994 through October 1996. They used late 486 and early Pentium processors.
Notable models include the 755CD which was one of the first laptops to market with an internal CD-ROM drive, and the 755CV and 755CDV, which both had a removable rear display cover that allowed the computer to be used with an overhead projector.
Specifications
| Spec | ThinkPad 755CS | ThinkPad 755C | ThinkPad 755CSE | ThinkPad 755CE | ThinkPad 755CD | ThinkPad 755CX | ThinkPad 755CV | ThinkPad 755CV |
|---|---|---|---|---|---|---|---|---|
| Release Date | June 1994 | November 1994 | October 1994 | May 1995 | ||||
| CPU | CPU Type: Unknown - Intel 486DX2 @50MHz - Intel 486DX4 @75MHz | CPU Type: Unknown Intel 486DX4 @100MHz | CPU Type: Unknown - Intel 486DX4 @100MHz - Intel Pentium @75MHz | CPU Type: Unknown Intel Pentium @75MHz | CPU Type: Unknown - Intel 486DX4 @100MHz - Intel Pentium @75MHz | |||
| Chipset | Unknown | |||||||
| RAM | Type: IC DRAM or 72-pin (w/ adapter) Standard: 4MB Maximum: 20MB (IC DRAM) or 36MB (72-pin) | Type: IC DRAM or 72-pin (w/ adapter) Standard: 8MB Maximum: 20MB (IC DRAM) or 40MB (72-pin) | Type: IC DRAM or 72-pin (w/ adapter) Standard: 8MB Maximum: 40MB | |||||
| Storage | 2.5" IDE Requires Adapter: Yes Standard: 170, 340, or 540MB | 2.5" IDE Requires Adapter: Yes Standard: 340, 540, or 810MB | 2.5" IDE Requires Adapter: Yes Standard: 540MB. 810MB, or 1.2GB | |||||
| Display Options | 9.5" Passive Matrix Color @640x480 | 10.4" Active Matrix Color @640x480 | 10.4" Passive Matrix Color @640x480 | 10.4" Active Matrix Color @640x480 | - 10.4" Active Matrix Color @640x480 (models without sound) - 10.4" Active Matrix Color @800x600 (models with sound) | 10.4" Active Matrix Color @640x480 | ||
| Graphics Chipset | Western Digital WD90C24A or WD90C24A2 VRAM: 1MB | Western Digital WD90C24A2 VRAM: 1MB | Western Digital WD90C24A (Rev C) VRAM: 1MB | Western Digital WD90C24A2 VRAM: 1MB | ||||
| Audio | Crystal CS4248 | IBM Mwave MDSP2780 | IBM Mwave MDSP2780 (Optional) | IBM Mwave MDSP2780 | ||||
| Main Battery | NiMH | NiMH or Lithium Ion (Penitum only) | NiMH or Lithium Ion | |||||
| CMOS Battery | Unknown | |||||||
| Power Supply | Proprietary 4-pin | |||||||
| Media Drives | Ultrabay (Original, no CD-ROM support) | Ultrabay Thick (CD-ROM support) | Ultrabay (No CD-ROM support) | |||||
| PC Cards | 2x PCMCIA Slots | |||||||
| Networking | None | Modem | Modem (models w/ sound) | Modem | ||||
| Other I/O | - 1x Parallel - 1x Serial - 1x VGA Out - 1x PS/2 - 1x Dock Connector - 1x Line In - 1x Line Out | - 1x Parallel - 1x Serial - 1x VGA Out - 1x PS/2 - 1x Dock Connector - 1x Line In - 1x Line Out - Infrared | - 1x Parallel - 1x Serial - 1x VGA Out - 1x PS/2 - 1x Dock Connector - 1x Line In - 1x Line Out - 1x Proprietary Multimedia Connector (I believe this includes game port and composite in/out) - Infrared | - 1x Parallel - 1x Serial - 1x VGA Out - 1x PS/2 - 1x Dock Connector - 1x Line In (models w/ sound) - 1x Line Out (models w/ sound) - Infrared | - 1x Parallel - 1x Serial - 1x VGA Out - 1x PS/2 - 1x Dock Connector - 1x Line In - 1x Line Out - Infrared | |||
| BIOS | IBM BIOS with Easy Setup | |||||||
| Pointing Device | TrackPoint | |||||||
Resources
 Service Manual |
Withdrawn Models PSREF |
|---|
Common Faults & Maintenance
The ThinkPad 755s are generally well-built laptops. Build quality is good, and hinge failures are rare. Still, a couple of things MUST be addressed to keep them working.
Reserve Battery Leaks
I'm not positive on this, but I believe the 755 series laptops have a Lithium CMOS battery somewhere inside. What I am sure of though, is that they ALSO have a VARTA NiMH battery, located under the Ultrabay. These batteries nearly always leak with age and MUST be removed or the laptop will eventually stop working.
Sticky Rubber
The entire case of the 755 ThinkPads is coated in a soft touch rubber coating. This coating nearly always turns sticky with age and must be removed from the laptop.
Capacitor Failure
The older 750 Series models are fully in the "need to recap" zone and these aren't far behind, if they're not already there as well. I believe the display has several electrolytic caps that may need replacing.
Gallery
If you own a 755 Series laptop and would like to send in photos I could use, email me: macdatnet@gmail.com
Page last updated (MM/DD/YYYY): 02/21/2025
Update Reason: converted to php
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