The other day I got hold of a Toshiba Satellite 460CDX laptop that had a broken display - which is DSTN so it's not something I would like to directly replace anyway:

I already have a Toshiba Satellite 230CX which is in very nice condition and that's the only 'X' toshiba laptop I want. These are interesting for the time they came from, these 'X' models were an 'Advanced DSTN' which updates faster, still has the cloudy low-contrast, dull-coloured look that DSTN displays are known for, but motion is more tolerably fast and the display is less 'noisy'. Still nowhere near as good as a TFT display so I want to replace with a TFT - in this case any of these ones: NEC NL8060BC31-05, Toshiba LTM12C270, Samsung LT121S1-101, Sharp LQ12S353. Those are all the display types that the 12.1" Toshiba laptops in the Satellite 230 / 440 / 445 / 460 / 465 series used, they're all the same size & shape, all use LVDS and run at 5v - that last part's important because 5v LVDS LCDs are quite rare now.
The 'Advanced DSTN' or HC-A (High Contrast - Addressing) as Sharp call it, solves some of the big problems of DSTN by putting the signals going from the mainboard to the LCD through some (for the time) high-speed serial data streams (like USB or PCI-E) with LVDS.
LVDS or low voltage differential signalling encapsulates a whole bunch of parallel display signals into a few high speed serial data streams that are decoded on the other end, which not only cuts down on wires required for the display but also improves/resolves crosstalk and noise issues that parallel displays struggle with. An 800x600 TFT of this era requires 4 LVDS streams (4 per chip) which covers 18-bits of colour data, hysnc, vsync, display-enable & clock. Clock is important & fast enough that it gets its own dedicated stream, while red/blue/green/hsync/vsync are split across the first 3 streams. That's ~15 wires to run the LCD instead of ~35, with better resulting signal/display quality - Toshiba seem to be one of the first to implement it and this 'modular' nature of LVDS makes this mod possible.
The 'Advanced DSTN' uses 8x LVDS streams / 2x LVDS transmitters which holds the data bits for the upper half & its control signals, then bits for the lower half & the control signals.

Note that there is also the Satellite 220CS / 220CDS based on a similar motherboard, but I don't have one. I checked it out and it's a very different design, so this modification is not applicable to the models ending in "S" rather than "X"!
(from my understanding of that mainboard design, it could run a TFT as well but would require some serious re-wiring)

Anyways, I have this Toshiba LTM12C270 in my spares box because it has a big white line through the upper section of the display and it's used for testing because of that.
I've suspected that the Toshiba Satellite 460CDT uses the same BIOS and motherboard PCB as the Toshiba Satellite 460CDX for a while now - looking back at Toshiba's PCB designs from that era, I consider them to be masterpieces of design in that the same mainboard PCB can drive a DSTN or TFT display with really minor component differences that would be selected on the pick'n'place machine.
The Satellite T21xx are older 486 laptops but they did the same trick - one BIOS and PCB covers all mono, colour DSTN and colour TFT laptops, with just some little resistors operating as switches to select which LCD type the graphics chip is told to drive.

The Satellite 400 to 430 series simplified this further by having the LCD cable itself tell the laptop which display type to drive, then the video card is the only part with different components populated. So with a Toshiba Satellite 430CDS base, I can install the video card, LCD cable and LCD from a Toshiba Satellite 430CDT and the Satellite 430CDS is then 100% the same as a factory Toshiba Satellite 430CDT, except for the underside label. No reprogramming or delicate soldering required. I think I scared some people away with my log of what's required to make a TFT work when you *don't* have the TFT version's LCD cable, video card and plastics available: Upgrading a Toshiba laptop from DSTN to TFT panel - The Satellite 400CS becomes a 400CDT

Back to the Satellite 460CDX, long ago I tried installing a TFT panel in place of an advanced DSTN panel and only saw a white screen - which means the display is not running / working. This meant the LCD cable doesn't decide what display the laptop should send data for. No harm done though, the power and ground pins are in the same places 😀
I've suspected it could be made into 'CDT' mode instead of 'CDX' mode with a small & simple solder jumper. Toshiba use consistent notation for 'jumper' components like 0-ohm resistors that go in one position or another to specify a setting - these are almost always Wx like W3, W6 etc instead of being C3 / L6 / R9.
I'm not just stumbling in the dark, nor can I refer to a schematic but I have at this point got a few CDX and CDT models to refer to, including a completely hopeless Satellite 460CDT where the battery had damaged so much it was unsave-able.
So let's compare the 460 CDX and CDT mainboards, zooming in on just the LCD handling areas to keep filesizes reasonable:

This is the top-side and we can see there are mostly the same parts, there is only 1x LVDS transmitter chip, there are some resistors in different positions coming off of the display chip, then I spotted that W33 & R474 are in opposite positions on the CDX (DSTN) & CDT (TFT) models.
Why is this a thing? The Chips B65554 video chip is instructed by the system bios which display type to drive. These are stored in the Chips video BIOS as several separate tables for DSTN, 640x480, TFT etc and the system BIOS runs a check on startup to see which display it should be driving, then instructs the Chips video BIOS to drive that display type. Some manufacturers use dip switches, jumpers, or the display cable itself (IBM Thinkpads, Toshiba 400>430 series) to decide which display type to drive, but this later Satellite 460CDX has the display type decided in the factory when the board is populated on the pick and place machine, so the same PCB could be a TFT or a DSTN model.

Seeing that small difference on components labelled "W33" and "R474" made me think that must be it - to test this I unhooked the LCD assembly entirely. How the LCD is driven is actually displayed in the BIOS for the laptop, a DSTN will show "256k colors" and a TFT will display "16M colors", something I learned when trying to get the 400CS / 400CDT to drive a TFT instead.
Look at that, swap over the W33 and R474 resistor positions and the laptop goes from DSTN display mode into TFT display mode:

The job is only halfway done though, the display mode is switched but all those light blue resistors on the top & bottom side of the board need to be moved to hook up all the right connections for the display chip's parallel data links to go into the correct pins on the left-side LVDS transmitter.
Here's what needs moving over - all the items highlighted in red need moving over to the positions highlighted in green, there will be many "330" light blue resistors left over. This is pretty easy to do with an iron tip that can cover both ends of the resistor. See the TS100 TS-KU tip to see what I mean, that's what I used.

Now with all that done, if you have the top-half of a CDT laptop it can then be installed and will work, here's the top-half of a 460CDT installed and working!

If you don't have the top half of a CDT laptop and want to put a TFT panel where DSTN panel was, without replacing the cable, then read on to the next post 😀